* [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered
@ 2024-05-10 0:29 Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 1/7] bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops Kui-Feng Lee
` (6 more replies)
0 siblings, 7 replies; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
The subsystems managing struct_ops objects may need to detach a
struct_ops object due to errors or other reasons. It would be useful
to notify user space programs so that error recovery or logging can be
carried out.
This patch set enables the detach feature for struct_ops links and
send an event to epoll when a link is detached. Subsystems could call
link->ops->detach() to detach a link and notify user space programs
through epoll.
The signatures of callback functions in "struct bpf_struct_ops" have
been changed as well to pass an extra link argument to
subsystems. Subsystems could detach the links received from reg() and
update() callbacks if there is. This also provides a way that
subsystems can distinguish registrations for an object that has been
registered multiple times for several links.
However, bpf struct_ops maps without BPF_F_LINK have no any link.
Subsystems will receive NULL link pointer for this case.
---
Changes from v2:
- Rephrased commit logs and comments.
- Addressed some mistakes from patch splitting.
- Replace mutex with spinlock in bpf_testmod.c to address lockdep
Splat and simplify the implementation.
- Fix an argument passing to rcu_dereference_protected().
Changes from v1:
- Pass a link to reg, unreg, and update callbacks.
- Provide a function to detach a link from underlying subsystems.
- Add a kfunc to minic detachments from subsystems, and provide a
flexible way to control when to do detachments.
- Add two tests to detach a link from the subsystem after the refcount
of the link drops to zero.
v2: https://lore.kernel.org/all/20240507055600.2382627-1-thinker.li@gmail.com/
v1: https://lore.kernel.org/all/20240429213609.487820-1-thinker.li@gmail.com/
Kui-Feng Lee (7):
bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops.
bpf: enable detaching links of struct_ops objects.
bpf: support epoll from bpf struct_ops links.
bpf: export bpf_link_inc_not_zero.
selftests/bpf: test struct_ops with epoll
selftests/bpf: detach a struct_ops link from the subsystem managing
it.
selftests/bpf: make sure bpf_testmod handling racing link destroying
well.
include/linux/bpf.h | 13 +-
kernel/bpf/bpf_struct_ops.c | 77 ++++++--
kernel/bpf/syscall.c | 14 +-
net/bpf/bpf_dummy_struct_ops.c | 4 +-
net/ipv4/bpf_tcp_ca.c | 6 +-
.../bpf/bpf_test_no_cfi/bpf_test_no_cfi.c | 4 +-
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 48 ++++-
.../bpf/bpf_testmod/bpf_testmod_kfunc.h | 1 +
.../bpf/prog_tests/test_struct_ops_module.c | 168 ++++++++++++++++++
.../selftests/bpf/progs/struct_ops_detach.c | 16 ++
10 files changed, 326 insertions(+), 25 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_detach.c
--
2.34.1
^ permalink raw reply [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 1/7] bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops.
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects Kui-Feng Lee
` (5 subsequent siblings)
6 siblings, 0 replies; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
Pass an additional pointer of bpf_struct_ops_link to callback function reg,
unreg, and update provided by subsystems defined in bpf_struct_ops. A
bpf_struct_ops_map can be registered for multiple links. Passing a pointer
of bpf_struct_ops_link helps subsystems to distinguish them.
This pointer will be used in the later patches to let the subsystem
initiate a detachment on a link that was registered to it previously.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
include/linux/bpf.h | 6 +++---
kernel/bpf/bpf_struct_ops.c | 10 +++++-----
net/bpf/bpf_dummy_struct_ops.c | 4 ++--
net/ipv4/bpf_tcp_ca.c | 6 +++---
.../selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c | 4 ++--
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 6 +++---
6 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 90094400cc63..b600767ebe02 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1730,9 +1730,9 @@ struct bpf_struct_ops {
int (*init_member)(const struct btf_type *t,
const struct btf_member *member,
void *kdata, const void *udata);
- int (*reg)(void *kdata);
- void (*unreg)(void *kdata);
- int (*update)(void *kdata, void *old_kdata);
+ int (*reg)(void *kdata, struct bpf_link *link);
+ void (*unreg)(void *kdata, struct bpf_link *link);
+ int (*update)(void *kdata, void *old_kdata, struct bpf_link *link);
int (*validate)(void *kdata);
void *cfi_stubs;
struct module *owner;
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 86c7884abaf8..1542dded7489 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -757,7 +757,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
goto unlock;
}
- err = st_ops->reg(kdata);
+ err = st_ops->reg(kdata, NULL);
if (likely(!err)) {
/* This refcnt increment on the map here after
* 'st_ops->reg()' is secure since the state of the
@@ -805,7 +805,7 @@ static long bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key)
BPF_STRUCT_OPS_STATE_TOBEFREE);
switch (prev_state) {
case BPF_STRUCT_OPS_STATE_INUSE:
- st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data);
+ st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, NULL);
bpf_map_put(map);
return 0;
case BPF_STRUCT_OPS_STATE_TOBEFREE:
@@ -1060,7 +1060,7 @@ static void bpf_struct_ops_map_link_dealloc(struct bpf_link *link)
/* st_link->map can be NULL if
* bpf_struct_ops_link_create() fails to register.
*/
- st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data);
+ st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, link);
bpf_map_put(&st_map->map);
}
kfree(st_link);
@@ -1125,7 +1125,7 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map
goto err_out;
}
- err = st_map->st_ops_desc->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data);
+ err = st_map->st_ops_desc->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data, link);
if (err)
goto err_out;
@@ -1176,7 +1176,7 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
if (err)
goto err_out;
- err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data);
+ err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data, &link->link);
if (err) {
bpf_link_cleanup(&link_primer);
link = NULL;
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
index 891cdf61c65a..3ea52b05adfb 100644
--- a/net/bpf/bpf_dummy_struct_ops.c
+++ b/net/bpf/bpf_dummy_struct_ops.c
@@ -272,12 +272,12 @@ static int bpf_dummy_init_member(const struct btf_type *t,
return -EOPNOTSUPP;
}
-static int bpf_dummy_reg(void *kdata)
+static int bpf_dummy_reg(void *kdata, struct bpf_link *link)
{
return -EOPNOTSUPP;
}
-static void bpf_dummy_unreg(void *kdata)
+static void bpf_dummy_unreg(void *kdata, struct bpf_link *link)
{
}
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 18227757ec0c..3f88d0961e5b 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -260,17 +260,17 @@ static int bpf_tcp_ca_check_member(const struct btf_type *t,
return 0;
}
-static int bpf_tcp_ca_reg(void *kdata)
+static int bpf_tcp_ca_reg(void *kdata, struct bpf_link *link)
{
return tcp_register_congestion_control(kdata);
}
-static void bpf_tcp_ca_unreg(void *kdata)
+static void bpf_tcp_ca_unreg(void *kdata, struct bpf_link *link)
{
tcp_unregister_congestion_control(kdata);
}
-static int bpf_tcp_ca_update(void *kdata, void *old_kdata)
+static int bpf_tcp_ca_update(void *kdata, void *old_kdata, struct bpf_link *link)
{
return tcp_update_congestion_control(kdata, old_kdata);
}
diff --git a/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c b/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c
index b1dd889d5d7d..948eb3962732 100644
--- a/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c
+++ b/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c
@@ -22,12 +22,12 @@ static int dummy_init_member(const struct btf_type *t,
return 0;
}
-static int dummy_reg(void *kdata)
+static int dummy_reg(void *kdata, struct bpf_link *link)
{
return 0;
}
-static void dummy_unreg(void *kdata)
+static void dummy_unreg(void *kdata, struct bpf_link *link)
{
}
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index e93013fc7bf4..1150e758e630 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -817,7 +817,7 @@ static const struct bpf_verifier_ops bpf_testmod_verifier_ops = {
.is_valid_access = bpf_testmod_ops_is_valid_access,
};
-static int bpf_dummy_reg(void *kdata)
+static int bpf_dummy_reg(void *kdata, struct bpf_link *link)
{
struct bpf_testmod_ops *ops = kdata;
@@ -832,7 +832,7 @@ static int bpf_dummy_reg(void *kdata)
return 0;
}
-static void bpf_dummy_unreg(void *kdata)
+static void bpf_dummy_unreg(void *kdata, struct bpf_link *link)
{
}
@@ -868,7 +868,7 @@ struct bpf_struct_ops bpf_bpf_testmod_ops = {
.owner = THIS_MODULE,
};
-static int bpf_dummy_reg2(void *kdata)
+static int bpf_dummy_reg2(void *kdata, struct bpf_link *link)
{
struct bpf_testmod_ops2 *ops = kdata;
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects.
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 1/7] bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
2024-05-21 1:22 ` Martin KaFai Lau
2024-05-10 0:29 ` [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links Kui-Feng Lee
` (4 subsequent siblings)
6 siblings, 1 reply; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
Implement the detach callback in bpf_link_ops for struct_ops so that user
programs can detach a struct_ops link. The subsystems that struct_ops
objects are registered to can also use this callback to detach the links
being passed to them.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
kernel/bpf/bpf_struct_ops.c | 50 ++++++++++++++++++++++++++++++++-----
1 file changed, 44 insertions(+), 6 deletions(-)
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 1542dded7489..7e270ee15f6e 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -1057,9 +1057,6 @@ static void bpf_struct_ops_map_link_dealloc(struct bpf_link *link)
st_map = (struct bpf_struct_ops_map *)
rcu_dereference_protected(st_link->map, true);
if (st_map) {
- /* st_link->map can be NULL if
- * bpf_struct_ops_link_create() fails to register.
- */
st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, link);
bpf_map_put(&st_map->map);
}
@@ -1075,7 +1072,8 @@ static void bpf_struct_ops_map_link_show_fdinfo(const struct bpf_link *link,
st_link = container_of(link, struct bpf_struct_ops_link, link);
rcu_read_lock();
map = rcu_dereference(st_link->map);
- seq_printf(seq, "map_id:\t%d\n", map->id);
+ if (map)
+ seq_printf(seq, "map_id:\t%d\n", map->id);
rcu_read_unlock();
}
@@ -1088,7 +1086,8 @@ static int bpf_struct_ops_map_link_fill_link_info(const struct bpf_link *link,
st_link = container_of(link, struct bpf_struct_ops_link, link);
rcu_read_lock();
map = rcu_dereference(st_link->map);
- info->struct_ops.map_id = map->id;
+ if (map)
+ info->struct_ops.map_id = map->id;
rcu_read_unlock();
return 0;
}
@@ -1113,6 +1112,10 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map
mutex_lock(&update_mutex);
old_map = rcu_dereference_protected(st_link->map, lockdep_is_held(&update_mutex));
+ if (!old_map) {
+ err = -EINVAL;
+ goto err_out;
+ }
if (expected_old_map && old_map != expected_old_map) {
err = -EPERM;
goto err_out;
@@ -1139,8 +1142,37 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map
return err;
}
+static int bpf_struct_ops_map_link_detach(struct bpf_link *link)
+{
+ struct bpf_struct_ops_link *st_link = container_of(link, struct bpf_struct_ops_link, link);
+ struct bpf_struct_ops_map *st_map;
+ struct bpf_map *map;
+
+ mutex_lock(&update_mutex);
+
+ map = rcu_dereference_protected(st_link->map, lockdep_is_held(&update_mutex));
+ if (!map) {
+ mutex_unlock(&update_mutex);
+ return -EINVAL;
+ }
+ st_map = container_of(map, struct bpf_struct_ops_map, map);
+
+ st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, link);
+
+ rcu_assign_pointer(st_link->map, NULL);
+ /* Pair with bpf_map_get() in bpf_struct_ops_link_create() or
+ * bpf_map_inc() in bpf_struct_ops_map_link_update().
+ */
+ bpf_map_put(&st_map->map);
+
+ mutex_unlock(&update_mutex);
+
+ return 0;
+}
+
static const struct bpf_link_ops bpf_struct_ops_map_lops = {
.dealloc = bpf_struct_ops_map_link_dealloc,
+ .detach = bpf_struct_ops_map_link_detach,
.show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
.fill_link_info = bpf_struct_ops_map_link_fill_link_info,
.update_map = bpf_struct_ops_map_link_update,
@@ -1176,13 +1208,19 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
if (err)
goto err_out;
+ /* Init link->map before calling reg() in case being detached
+ * immediately.
+ */
+ RCU_INIT_POINTER(link->map, map);
+
err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data, &link->link);
if (err) {
+ RCU_INIT_POINTER(link->map, NULL);
bpf_link_cleanup(&link_primer);
+ /* The link has been free by bpf_link_cleanup() */
link = NULL;
goto err_out;
}
- RCU_INIT_POINTER(link->map, map);
return bpf_link_settle(&link_primer);
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links.
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 1/7] bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
2024-05-21 1:26 ` Martin KaFai Lau
2024-05-10 0:29 ` [PATCH bpf-next v3 4/7] bpf: export bpf_link_inc_not_zero Kui-Feng Lee
` (3 subsequent siblings)
6 siblings, 1 reply; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
Add epoll support to bpf struct_ops links to trigger EPOLLHUP event upon
detachment.
This patch implements the "poll" of the "struct file_operations" for BPF
links and introduces a new "poll" operator in the "struct bpf_link_ops". By
implementing "poll" of "struct bpf_link_ops" for the links of struct_ops,
the file descriptor of a struct_ops link can be added to an epoll file
descriptor to receive EPOLLHUP events.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
include/linux/bpf.h | 1 +
kernel/bpf/bpf_struct_ops.c | 17 +++++++++++++++++
kernel/bpf/syscall.c | 11 +++++++++++
3 files changed, 29 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b600767ebe02..5f7496ef8b7c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1612,6 +1612,7 @@ struct bpf_link_ops {
struct bpf_link_info *info);
int (*update_map)(struct bpf_link *link, struct bpf_map *new_map,
struct bpf_map *old_map);
+ __poll_t (*poll)(struct file *file, struct poll_table_struct *pts);
};
struct bpf_tramp_link {
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 7e270ee15f6e..497526bd5fec 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -12,6 +12,7 @@
#include <linux/mutex.h>
#include <linux/btf_ids.h>
#include <linux/rcupdate_wait.h>
+#include <linux/poll.h>
struct bpf_struct_ops_value {
struct bpf_struct_ops_common_value common;
@@ -56,6 +57,7 @@ struct bpf_struct_ops_map {
struct bpf_struct_ops_link {
struct bpf_link link;
struct bpf_map __rcu *map;
+ wait_queue_head_t wait_hup;
};
static DEFINE_MUTEX(update_mutex);
@@ -1167,15 +1169,28 @@ static int bpf_struct_ops_map_link_detach(struct bpf_link *link)
mutex_unlock(&update_mutex);
+ wake_up_interruptible_poll(&st_link->wait_hup, EPOLLHUP);
+
return 0;
}
+static __poll_t bpf_struct_ops_map_link_poll(struct file *file,
+ struct poll_table_struct *pts)
+{
+ struct bpf_struct_ops_link *st_link = file->private_data;
+
+ poll_wait(file, &st_link->wait_hup, pts);
+
+ return (st_link->map) ? 0 : EPOLLHUP;
+}
+
static const struct bpf_link_ops bpf_struct_ops_map_lops = {
.dealloc = bpf_struct_ops_map_link_dealloc,
.detach = bpf_struct_ops_map_link_detach,
.show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
.fill_link_info = bpf_struct_ops_map_link_fill_link_info,
.update_map = bpf_struct_ops_map_link_update,
+ .poll = bpf_struct_ops_map_link_poll,
};
int bpf_struct_ops_link_create(union bpf_attr *attr)
@@ -1213,6 +1228,8 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
*/
RCU_INIT_POINTER(link->map, map);
+ init_waitqueue_head(&link->wait_hup);
+
err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data, &link->link);
if (err) {
RCU_INIT_POINTER(link->map, NULL);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 13ad74ecf2cd..ad4f81ed27f0 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3150,6 +3150,16 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
}
#endif
+static __poll_t bpf_link_poll(struct file *file, struct poll_table_struct *pts)
+{
+ struct bpf_link *link = file->private_data;
+
+ if (link->ops->poll)
+ return link->ops->poll(file, pts);
+
+ return 0;
+}
+
static const struct file_operations bpf_link_fops = {
#ifdef CONFIG_PROC_FS
.show_fdinfo = bpf_link_show_fdinfo,
@@ -3157,6 +3167,7 @@ static const struct file_operations bpf_link_fops = {
.release = bpf_link_release,
.read = bpf_dummy_read,
.write = bpf_dummy_write,
+ .poll = bpf_link_poll,
};
static int bpf_link_alloc_id(struct bpf_link *link)
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 4/7] bpf: export bpf_link_inc_not_zero.
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
` (2 preceding siblings ...)
2024-05-10 0:29 ` [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 5/7] selftests/bpf: test struct_ops with epoll Kui-Feng Lee
` (2 subsequent siblings)
6 siblings, 0 replies; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
bpf_link_inc_not_zero() will be used by kernel modules. We will use it in
bpf_testmod.c later.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
include/linux/bpf.h | 6 ++++++
kernel/bpf/syscall.c | 3 ++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5f7496ef8b7c..6b592094f9b4 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2351,6 +2351,7 @@ int bpf_link_prime(struct bpf_link *link, struct bpf_link_primer *primer);
int bpf_link_settle(struct bpf_link_primer *primer);
void bpf_link_cleanup(struct bpf_link_primer *primer);
void bpf_link_inc(struct bpf_link *link);
+struct bpf_link *bpf_link_inc_not_zero(struct bpf_link *link);
void bpf_link_put(struct bpf_link *link);
int bpf_link_new_fd(struct bpf_link *link);
struct bpf_link *bpf_link_get_from_fd(u32 ufd);
@@ -2722,6 +2723,11 @@ static inline void bpf_link_inc(struct bpf_link *link)
{
}
+static inline struct bpf_link *bpf_link_inc_not_zero(struct bpf_link *link)
+{
+ return NULL;
+}
+
static inline void bpf_link_put(struct bpf_link *link)
{
}
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index ad4f81ed27f0..31fabe26371d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5422,10 +5422,11 @@ static int link_detach(union bpf_attr *attr)
return ret;
}
-static struct bpf_link *bpf_link_inc_not_zero(struct bpf_link *link)
+struct bpf_link *bpf_link_inc_not_zero(struct bpf_link *link)
{
return atomic64_fetch_add_unless(&link->refcnt, 1, 0) ? link : ERR_PTR(-ENOENT);
}
+EXPORT_SYMBOL(bpf_link_inc_not_zero);
struct bpf_link *bpf_link_by_id(u32 id)
{
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 5/7] selftests/bpf: test struct_ops with epoll
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
` (3 preceding siblings ...)
2024-05-10 0:29 ` [PATCH bpf-next v3 4/7] bpf: export bpf_link_inc_not_zero Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 7/7] selftests/bpf: make sure bpf_testmod handling racing link destroying well Kui-Feng Lee
6 siblings, 0 replies; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
Verify whether a user space program is informed through epoll with EPOLLHUP
when a struct_ops object is detached.
The BPF code in selftests/bpf/progs/struct_ops_module.c has become
complex. Therefore, struct_ops_detach.c has been added to segregate the BPF
code for detachment tests from the BPF code for other tests based on the
recommendation of Andrii Nakryiko.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
.../bpf/prog_tests/test_struct_ops_module.c | 57 +++++++++++++++++++
.../selftests/bpf/progs/struct_ops_detach.c | 9 +++
2 files changed, 66 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_detach.c
diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
index 29e183a80f49..bbcf12696a6b 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
@@ -3,9 +3,12 @@
#include <test_progs.h>
#include <time.h>
+#include <sys/epoll.h>
+
#include "struct_ops_module.skel.h"
#include "struct_ops_nulled_out_cb.skel.h"
#include "struct_ops_forgotten_cb.skel.h"
+#include "struct_ops_detach.skel.h"
static void check_map_info(struct bpf_map_info *info)
{
@@ -242,6 +245,58 @@ static void test_struct_ops_forgotten_cb(void)
struct_ops_forgotten_cb__destroy(skel);
}
+/* Detach a link from a user space program */
+static void test_detach_link(void)
+{
+ struct epoll_event ev, events[2];
+ struct struct_ops_detach *skel;
+ struct bpf_link *link = NULL;
+ int fd, epollfd = -1, nfds;
+ int err;
+
+ skel = struct_ops_detach__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "struct_ops_detach__open_and_load"))
+ return;
+
+ link = bpf_map__attach_struct_ops(skel->maps.testmod_do_detach);
+ if (!ASSERT_OK_PTR(link, "attach_struct_ops"))
+ goto cleanup;
+
+ fd = bpf_link__fd(link);
+ if (!ASSERT_GE(fd, 0, "link_fd"))
+ goto cleanup;
+
+ epollfd = epoll_create1(0);
+ if (!ASSERT_GE(epollfd, 0, "epoll_create1"))
+ goto cleanup;
+
+ ev.events = EPOLLHUP;
+ ev.data.fd = fd;
+ err = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
+ if (!ASSERT_OK(err, "epoll_ctl"))
+ goto cleanup;
+
+ err = bpf_link__detach(link);
+ if (!ASSERT_OK(err, "detach_link"))
+ goto cleanup;
+
+ /* Wait for EPOLLHUP */
+ nfds = epoll_wait(epollfd, events, 2, 500);
+ if (!ASSERT_EQ(nfds, 1, "epoll_wait"))
+ goto cleanup;
+
+ if (!ASSERT_EQ(events[0].data.fd, fd, "epoll_wait_fd"))
+ goto cleanup;
+ if (!ASSERT_TRUE(events[0].events & EPOLLHUP, "events[0].events"))
+ goto cleanup;
+
+cleanup:
+ if (epollfd >= 0)
+ close(epollfd);
+ bpf_link__destroy(link);
+ struct_ops_detach__destroy(skel);
+}
+
void serial_test_struct_ops_module(void)
{
if (test__start_subtest("struct_ops_load"))
@@ -254,5 +309,7 @@ void serial_test_struct_ops_module(void)
test_struct_ops_nulled_out_cb();
if (test__start_subtest("struct_ops_forgotten_cb"))
test_struct_ops_forgotten_cb();
+ if (test__start_subtest("test_detach_link"))
+ test_detach_link();
}
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_detach.c b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
new file mode 100644
index 000000000000..45eacc2ca657
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+#include <vmlinux.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_do_detach;
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it.
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
` (4 preceding siblings ...)
2024-05-10 0:29 ` [PATCH bpf-next v3 5/7] selftests/bpf: test struct_ops with epoll Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
2024-05-21 22:56 ` Amery Hung
2024-05-10 0:29 ` [PATCH bpf-next v3 7/7] selftests/bpf: make sure bpf_testmod handling racing link destroying well Kui-Feng Lee
6 siblings, 1 reply; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
Not only a user space program can detach a struct_ops link, the subsystem
managing a link can also detach the link. This patch adds a kfunc to
simulate detaching a link by the subsystem managing it and makes sure user
space programs get notified through epoll.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 42 ++++++++++++
.../bpf/bpf_testmod/bpf_testmod_kfunc.h | 1 +
.../bpf/prog_tests/test_struct_ops_module.c | 67 +++++++++++++++++++
.../selftests/bpf/progs/struct_ops_detach.c | 7 ++
4 files changed, 117 insertions(+)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 1150e758e630..1f347eed6c18 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -741,6 +741,38 @@ __bpf_kfunc int bpf_kfunc_call_kernel_getpeername(struct addr_args *args)
return err;
}
+static DEFINE_SPINLOCK(detach_lock);
+static struct bpf_link *link_to_detach;
+
+__bpf_kfunc int bpf_dummy_do_link_detach(void)
+{
+ struct bpf_link *link;
+ int ret = -ENOENT;
+
+ /* A subsystem must ensure that a link is valid when detaching the
+ * link. In order to achieve that, the subsystem may need to obtain
+ * a lock to safeguard a table that holds the pointer to the link
+ * being detached. However, the subsystem cannot invoke
+ * link->ops->detach() while holding the lock because other tasks
+ * may be in the process of unregistering, which could lead to
+ * acquiring the same lock and causing a deadlock. This is why
+ * bpf_link_inc_not_zero() is used to maintain the link's validity.
+ */
+ spin_lock(&detach_lock);
+ link = link_to_detach;
+ /* Make sure the link is still valid by increasing its refcnt */
+ if (link && IS_ERR(bpf_link_inc_not_zero(link)))
+ link = NULL;
+ spin_unlock(&detach_lock);
+
+ if (link) {
+ ret = link->ops->detach(link);
+ bpf_link_put(link);
+ }
+
+ return ret;
+}
+
BTF_KFUNCS_START(bpf_testmod_check_kfunc_ids)
BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc)
BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
@@ -777,6 +809,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_sendmsg, KF_SLEEPABLE)
BTF_ID_FLAGS(func, bpf_kfunc_call_sock_sendmsg, KF_SLEEPABLE)
BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_getsockname, KF_SLEEPABLE)
BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_getpeername, KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_dummy_do_link_detach)
BTF_KFUNCS_END(bpf_testmod_check_kfunc_ids)
static int bpf_testmod_ops_init(struct btf *btf)
@@ -829,11 +862,20 @@ static int bpf_dummy_reg(void *kdata, struct bpf_link *link)
if (ops->test_2)
ops->test_2(4, ops->data);
+ spin_lock(&detach_lock);
+ if (!link_to_detach)
+ link_to_detach = link;
+ spin_unlock(&detach_lock);
+
return 0;
}
static void bpf_dummy_unreg(void *kdata, struct bpf_link *link)
{
+ spin_lock(&detach_lock);
+ if (link == link_to_detach)
+ link_to_detach = NULL;
+ spin_unlock(&detach_lock);
}
static int bpf_testmod_test_1(void)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
index b0d586a6751f..19131baf4a9e 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
@@ -121,6 +121,7 @@ void bpf_kfunc_call_test_fail1(struct prog_test_fail1 *p);
void bpf_kfunc_call_test_fail2(struct prog_test_fail2 *p);
void bpf_kfunc_call_test_fail3(struct prog_test_fail3 *p);
void bpf_kfunc_call_test_mem_len_fail1(void *mem, int len);
+int bpf_dummy_do_link_detach(void) __ksym;
void bpf_kfunc_common_test(void) __ksym;
diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
index bbcf12696a6b..f4000bf04752 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
@@ -2,6 +2,7 @@
/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
#include <time.h>
+#include <network_helpers.h>
#include <sys/epoll.h>
@@ -297,6 +298,70 @@ static void test_detach_link(void)
struct_ops_detach__destroy(skel);
}
+/* Detach a link from the subsystem that the link was registered to */
+static void test_subsystem_detach(void)
+{
+ LIBBPF_OPTS(bpf_test_run_opts, topts,
+ .data_in = &pkt_v4,
+ .data_size_in = sizeof(pkt_v4));
+ struct epoll_event ev, events[2];
+ struct struct_ops_detach *skel;
+ struct bpf_link *link = NULL;
+ int fd, epollfd = -1, nfds;
+ int prog_fd;
+ int err;
+
+ skel = struct_ops_detach__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "struct_ops_detach_open_and_load"))
+ return;
+
+ link = bpf_map__attach_struct_ops(skel->maps.testmod_do_detach);
+ if (!ASSERT_OK_PTR(link, "attach_struct_ops"))
+ goto cleanup;
+
+ fd = bpf_link__fd(link);
+ if (!ASSERT_GE(fd, 0, "link_fd"))
+ goto cleanup;
+
+ prog_fd = bpf_program__fd(skel->progs.start_detach);
+ if (!ASSERT_GE(prog_fd, 0, "start_detach_fd"))
+ goto cleanup;
+
+ /* Do detachment from the registered subsystem */
+ err = bpf_prog_test_run_opts(prog_fd, &topts);
+ if (!ASSERT_OK(err, "start_detach_run"))
+ goto cleanup;
+
+ if (!ASSERT_EQ(topts.retval, 0, "start_detach_run_retval"))
+ goto cleanup;
+
+ epollfd = epoll_create1(0);
+ if (!ASSERT_GE(epollfd, 0, "epoll_create1"))
+ goto cleanup;
+
+ ev.events = EPOLLHUP;
+ ev.data.fd = fd;
+ err = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
+ if (!ASSERT_OK(err, "epoll_ctl"))
+ goto cleanup;
+
+ /* Wait for EPOLLHUP */
+ nfds = epoll_wait(epollfd, events, 2, 5000);
+ if (!ASSERT_EQ(nfds, 1, "epoll_wait"))
+ goto cleanup;
+
+ if (!ASSERT_EQ(events[0].data.fd, fd, "epoll_wait_fd"))
+ goto cleanup;
+ if (!ASSERT_TRUE(events[0].events & EPOLLHUP, "events[0].events"))
+ goto cleanup;
+
+cleanup:
+ if (epollfd >= 0)
+ close(epollfd);
+ bpf_link__destroy(link);
+ struct_ops_detach__destroy(skel);
+}
+
void serial_test_struct_ops_module(void)
{
if (test__start_subtest("struct_ops_load"))
@@ -311,5 +376,7 @@ void serial_test_struct_ops_module(void)
test_struct_ops_forgotten_cb();
if (test__start_subtest("test_detach_link"))
test_detach_link();
+ if (test__start_subtest("test_subsystem_detach"))
+ test_subsystem_detach();
}
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_detach.c b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
index 45eacc2ca657..5c742b0df04d 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_detach.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
@@ -2,8 +2,15 @@
/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include "../bpf_testmod/bpf_testmod.h"
+#include "../bpf_testmod/bpf_testmod_kfunc.h"
char _license[] SEC("license") = "GPL";
SEC(".struct_ops.link")
struct bpf_testmod_ops testmod_do_detach;
+
+SEC("tc")
+int start_detach(void *skb)
+{
+ return bpf_dummy_do_link_detach();
+}
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH bpf-next v3 7/7] selftests/bpf: make sure bpf_testmod handling racing link destroying well.
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
` (5 preceding siblings ...)
2024-05-10 0:29 ` [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it Kui-Feng Lee
@ 2024-05-10 0:29 ` Kui-Feng Lee
6 siblings, 0 replies; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-10 0:29 UTC (permalink / raw
To: bpf, ast, martin.lau, song, kernel-team, andrii
Cc: sinquersw, kuifeng, Kui-Feng Lee
Do detachment from the subsystem after a link being closed/freed. This
test make sure the pattern implemented by bpf_dummy_do_link_detach() works
correctly.
Refer to bpf_dummy_do_link_detach() in bpf_testmod.c for more details.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
.../bpf/prog_tests/test_struct_ops_module.c | 44 +++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
index f4000bf04752..3a8cdf440edd 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
@@ -362,6 +362,48 @@ static void test_subsystem_detach(void)
struct_ops_detach__destroy(skel);
}
+/* A subsystem detaches a link while the link is going to be free. */
+static void test_subsystem_detach_free(void)
+{
+ LIBBPF_OPTS(bpf_test_run_opts, topts,
+ .data_in = &pkt_v4,
+ .data_size_in = sizeof(pkt_v4));
+ struct struct_ops_detach *skel;
+ struct bpf_link *link = NULL;
+ int prog_fd;
+ int err;
+
+ skel = struct_ops_detach__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "struct_ops_detach_open_and_load"))
+ return;
+
+ link = bpf_map__attach_struct_ops(skel->maps.testmod_do_detach);
+ if (!ASSERT_OK_PTR(link, "attach_struct_ops"))
+ goto cleanup;
+
+ bpf_link__destroy(link);
+
+ prog_fd = bpf_program__fd(skel->progs.start_detach);
+ if (!ASSERT_GE(prog_fd, 0, "start_detach_fd"))
+ goto cleanup;
+
+ /* Do detachment from the registered subsystem */
+ err = bpf_prog_test_run_opts(prog_fd, &topts);
+ if (!ASSERT_OK(err, "start_detach_run"))
+ goto cleanup;
+
+ /* The link has zeroed refcount value or even has been
+ * unregistered, so the detachment from the subsystem should fail.
+ */
+ ASSERT_EQ(topts.retval, (u32)-ENOENT, "start_detach_run_retval");
+
+ /* Sync RCU to make sure the link is freed without any crash */
+ ASSERT_OK(kern_sync_rcu(), "kern_sync_rcu");
+
+cleanup:
+ struct_ops_detach__destroy(skel);
+}
+
void serial_test_struct_ops_module(void)
{
if (test__start_subtest("struct_ops_load"))
@@ -378,5 +420,7 @@ void serial_test_struct_ops_module(void)
test_detach_link();
if (test__start_subtest("test_subsystem_detach"))
test_subsystem_detach();
+ if (test__start_subtest("test_subsystem_detach_free"))
+ test_subsystem_detach_free();
}
--
2.34.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects.
2024-05-10 0:29 ` [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects Kui-Feng Lee
@ 2024-05-21 1:22 ` Martin KaFai Lau
2024-05-21 7:30 ` Kui-Feng Lee
0 siblings, 1 reply; 16+ messages in thread
From: Martin KaFai Lau @ 2024-05-21 1:22 UTC (permalink / raw
To: Kui-Feng Lee; +Cc: sinquersw, kuifeng, bpf, ast, song, kernel-team, andrii
On 5/9/24 5:29 PM, Kui-Feng Lee wrote:
> +static int bpf_struct_ops_map_link_detach(struct bpf_link *link)
> +{
> + struct bpf_struct_ops_link *st_link = container_of(link, struct bpf_struct_ops_link, link);
> + struct bpf_struct_ops_map *st_map;
> + struct bpf_map *map;
> +
> + mutex_lock(&update_mutex);
> +
> + map = rcu_dereference_protected(st_link->map, lockdep_is_held(&update_mutex));
> + if (!map) {
> + mutex_unlock(&update_mutex);
> + return -EINVAL;
> + }
> + st_map = container_of(map, struct bpf_struct_ops_map, map);
> +
> + st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, link);
> +
> + rcu_assign_pointer(st_link->map, NULL);
> + /* Pair with bpf_map_get() in bpf_struct_ops_link_create() or
> + * bpf_map_inc() in bpf_struct_ops_map_link_update().
> + */
> + bpf_map_put(&st_map->map);
> +
> + mutex_unlock(&update_mutex);
> +
> + return 0;
> +}
> +
> static const struct bpf_link_ops bpf_struct_ops_map_lops = {
> .dealloc = bpf_struct_ops_map_link_dealloc,
> + .detach = bpf_struct_ops_map_link_detach,
> .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
> .fill_link_info = bpf_struct_ops_map_link_fill_link_info,
> .update_map = bpf_struct_ops_map_link_update,
> @@ -1176,13 +1208,19 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
> if (err)
> goto err_out;
>
> + /* Init link->map before calling reg() in case being detached
> + * immediately.
> + */
It is not obvious in the patch how this (immediate detach by subsystem after
reg) may work without race, so I think it is easier to ask.
[ I put back the err_out context at the end ]
> + RCU_INIT_POINTER(link->map, map);
> +
> err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data, &link->link);
> if (err) {
> + RCU_INIT_POINTER(link->map, NULL);
In the bpf_struct_ops_map_link_detach() above, the update to link->map is
protected by the update_mutex. Could you explain how the link->map update to
NULL is safe here without holding the update_mutex?
> bpf_link_cleanup(&link_primer);
> + /* The link has been free by bpf_link_cleanup() */
> link = NULL;
> goto err_out;
> }
> - RCU_INIT_POINTER(link->map, map);
>
> return bpf_link_settle(&link_primer);
>
err_out:
bpf_map_put(map);
kfree(link);
return err;
}
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links.
2024-05-10 0:29 ` [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links Kui-Feng Lee
@ 2024-05-21 1:26 ` Martin KaFai Lau
2024-05-21 7:31 ` Kui-Feng Lee
0 siblings, 1 reply; 16+ messages in thread
From: Martin KaFai Lau @ 2024-05-21 1:26 UTC (permalink / raw
To: Kui-Feng Lee; +Cc: sinquersw, kuifeng, bpf, ast, song, kernel-team, andrii
On 5/9/24 5:29 PM, Kui-Feng Lee wrote:
> +static __poll_t bpf_struct_ops_map_link_poll(struct file *file,
> + struct poll_table_struct *pts)
> +{
> + struct bpf_struct_ops_link *st_link = file->private_data;
> +
> + poll_wait(file, &st_link->wait_hup, pts);
> +
> + return (st_link->map) ? 0 : EPOLLHUP;
nit. It should need a rcu_access_pointer(st_link->map).
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects.
2024-05-21 1:22 ` Martin KaFai Lau
@ 2024-05-21 7:30 ` Kui-Feng Lee
2024-05-21 18:09 ` Martin KaFai Lau
0 siblings, 1 reply; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-21 7:30 UTC (permalink / raw
To: Martin KaFai Lau, Kui-Feng Lee
Cc: kuifeng, bpf, ast, song, kernel-team, andrii
On 5/20/24 18:22, Martin KaFai Lau wrote:
> On 5/9/24 5:29 PM, Kui-Feng Lee wrote:
>> +static int bpf_struct_ops_map_link_detach(struct bpf_link *link)
>> +{
>> + struct bpf_struct_ops_link *st_link = container_of(link, struct
>> bpf_struct_ops_link, link);
>> + struct bpf_struct_ops_map *st_map;
>> + struct bpf_map *map;
>> +
>> + mutex_lock(&update_mutex);
>> +
>> + map = rcu_dereference_protected(st_link->map,
>> lockdep_is_held(&update_mutex));
>> + if (!map) {
>> + mutex_unlock(&update_mutex);
>> + return -EINVAL;
>> + }
>> + st_map = container_of(map, struct bpf_struct_ops_map, map);
>> +
>> + st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, link);
>> +
>> + rcu_assign_pointer(st_link->map, NULL);
>> + /* Pair with bpf_map_get() in bpf_struct_ops_link_create() or
>> + * bpf_map_inc() in bpf_struct_ops_map_link_update().
>> + */
>> + bpf_map_put(&st_map->map);
>> +
>> + mutex_unlock(&update_mutex);
>> +
>> + return 0;
>> +}
>> +
>> static const struct bpf_link_ops bpf_struct_ops_map_lops = {
>> .dealloc = bpf_struct_ops_map_link_dealloc,
>> + .detach = bpf_struct_ops_map_link_detach,
>> .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
>> .fill_link_info = bpf_struct_ops_map_link_fill_link_info,
>> .update_map = bpf_struct_ops_map_link_update,
>> @@ -1176,13 +1208,19 @@ int bpf_struct_ops_link_create(union bpf_attr
>> *attr)
>> if (err)
>> goto err_out;
>> + /* Init link->map before calling reg() in case being detached
>> + * immediately.
>> + */
>
> It is not obvious in the patch how this (immediate detach by subsystem
> after reg) may work without race, so I think it is easier to ask.
>
> [ I put back the err_out context at the end ]
>
>> + RCU_INIT_POINTER(link->map, map);
>> +
>> err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data,
>> &link->link);
>> if (err) {
>> + RCU_INIT_POINTER(link->map, NULL);
>
> In the bpf_struct_ops_map_link_detach() above, the update to link->map
> is protected by the update_mutex. Could you explain how the link->map
> update to NULL is safe here without holding the update_mutex?
If err is not zero, it means the subsystem rejects the pair of the
object and the link passing in. So, it has no reasonable to call
bpf_struct_ops_map_link_detach() for this link.
Does it make sense to you?
>
>> bpf_link_cleanup(&link_primer);
>> + /* The link has been free by bpf_link_cleanup() */
>> link = NULL;
>> goto err_out;
>> }
At this point, we don't change the content of the link anymore except
changing link->fd in bpf_link_settle(). So, it should be safe to call
bpf_struct_ops_map_link_detach() from the subsystem.
Should I explain it in a comment if you think it makes sense to you?
>> - RCU_INIT_POINTER(link->map, map);
>> return bpf_link_settle(&link_primer);
>>
>
> err_out:
> bpf_map_put(map);
> kfree(link);
> return err;
> }
>
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links.
2024-05-21 1:26 ` Martin KaFai Lau
@ 2024-05-21 7:31 ` Kui-Feng Lee
0 siblings, 0 replies; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-21 7:31 UTC (permalink / raw
To: Martin KaFai Lau, Kui-Feng Lee
Cc: kuifeng, bpf, ast, song, kernel-team, andrii
On 5/20/24 18:26, Martin KaFai Lau wrote:
> On 5/9/24 5:29 PM, Kui-Feng Lee wrote:
>> +static __poll_t bpf_struct_ops_map_link_poll(struct file *file,
>> + struct poll_table_struct *pts)
>> +{
>> + struct bpf_struct_ops_link *st_link = file->private_data;
>> +
>> + poll_wait(file, &st_link->wait_hup, pts);
>> +
>> + return (st_link->map) ? 0 : EPOLLHUP;
>
> nit. It should need a rcu_access_pointer(st_link->map).
>
sure
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects.
2024-05-21 7:30 ` Kui-Feng Lee
@ 2024-05-21 18:09 ` Martin KaFai Lau
0 siblings, 0 replies; 16+ messages in thread
From: Martin KaFai Lau @ 2024-05-21 18:09 UTC (permalink / raw
To: Kui-Feng Lee, Kui-Feng Lee; +Cc: kuifeng, bpf, ast, song, kernel-team, andrii
On 5/21/24 12:30 AM, Kui-Feng Lee wrote:
>
>
> On 5/20/24 18:22, Martin KaFai Lau wrote:
>> On 5/9/24 5:29 PM, Kui-Feng Lee wrote:
>>> +static int bpf_struct_ops_map_link_detach(struct bpf_link *link)
>>> +{
>>> + struct bpf_struct_ops_link *st_link = container_of(link, struct
>>> bpf_struct_ops_link, link);
>>> + struct bpf_struct_ops_map *st_map;
>>> + struct bpf_map *map;
>>> +
>>> + mutex_lock(&update_mutex);
>>> +
>>> + map = rcu_dereference_protected(st_link->map,
>>> lockdep_is_held(&update_mutex));
>>> + if (!map) {
>>> + mutex_unlock(&update_mutex);
>>> + return -EINVAL;
>>> + }
>>> + st_map = container_of(map, struct bpf_struct_ops_map, map);
>>> +
>>> + st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data, link);
>>> +
>>> + rcu_assign_pointer(st_link->map, NULL);
>>> + /* Pair with bpf_map_get() in bpf_struct_ops_link_create() or
>>> + * bpf_map_inc() in bpf_struct_ops_map_link_update().
>>> + */
>>> + bpf_map_put(&st_map->map);
>>> +
>>> + mutex_unlock(&update_mutex);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> static const struct bpf_link_ops bpf_struct_ops_map_lops = {
>>> .dealloc = bpf_struct_ops_map_link_dealloc,
>>> + .detach = bpf_struct_ops_map_link_detach,
>>> .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
>>> .fill_link_info = bpf_struct_ops_map_link_fill_link_info,
>>> .update_map = bpf_struct_ops_map_link_update,
>>> @@ -1176,13 +1208,19 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
>>> if (err)
>>> goto err_out;
>>> + /* Init link->map before calling reg() in case being detached
>>> + * immediately.
>>> + */
>>
>> It is not obvious in the patch how this (immediate detach by subsystem after
>> reg) may work without race, so I think it is easier to ask.
>>
>> [ I put back the err_out context at the end ]
>>
>>> + RCU_INIT_POINTER(link->map, map);
>>> +
>>> err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data, &link->link);
>>> if (err) {
>>> + RCU_INIT_POINTER(link->map, NULL);
>>
>> In the bpf_struct_ops_map_link_detach() above, the update to link->map is
>> protected by the update_mutex. Could you explain how the link->map update to
>> NULL is safe here without holding the update_mutex?
>
> If err is not zero, it means the subsystem rejects the pair of the
> object and the link passing in. So, it has no reasonable to call
> bpf_struct_ops_map_link_detach() for this link.
>
> Does it make sense to you?
>
>>
>>> bpf_link_cleanup(&link_primer);
>>> + /* The link has been free by bpf_link_cleanup() */
>>> link = NULL;
>>> goto err_out;
>>> }
>
> At this point, we don't change the content of the link anymore except
> changing link->fd in bpf_link_settle(). So, it should be safe to call
> bpf_struct_ops_map_link_detach() from the subsystem.
>
> Should I explain it in a comment if you think it makes sense to you?
It makes sense and will be useful to get this details in the comment.
>
>>> - RCU_INIT_POINTER(link->map, map);
>>> return bpf_link_settle(&link_primer);
>>>
>>
>> err_out:
>> bpf_map_put(map);
>> kfree(link);
>> return err;
>> }
>>
>>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it.
2024-05-10 0:29 ` [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it Kui-Feng Lee
@ 2024-05-21 22:56 ` Amery Hung
2024-05-22 0:31 ` Kui-Feng Lee
0 siblings, 1 reply; 16+ messages in thread
From: Amery Hung @ 2024-05-21 22:56 UTC (permalink / raw
To: Kui-Feng Lee
Cc: bpf, ast, martin.lau, song, kernel-team, andrii, sinquersw,
kuifeng
On Thu, May 09, 2024 at 05:29:41PM -0700, Kui-Feng Lee wrote:
> Not only a user space program can detach a struct_ops link, the subsystem
> managing a link can also detach the link. This patch adds a kfunc to
> simulate detaching a link by the subsystem managing it and makes sure user
> space programs get notified through epoll.
>
> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
> ---
> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 42 ++++++++++++
> .../bpf/bpf_testmod/bpf_testmod_kfunc.h | 1 +
> .../bpf/prog_tests/test_struct_ops_module.c | 67 +++++++++++++++++++
> .../selftests/bpf/progs/struct_ops_detach.c | 7 ++
> 4 files changed, 117 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> index 1150e758e630..1f347eed6c18 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> @@ -741,6 +741,38 @@ __bpf_kfunc int bpf_kfunc_call_kernel_getpeername(struct addr_args *args)
> return err;
> }
>
> +static DEFINE_SPINLOCK(detach_lock);
> +static struct bpf_link *link_to_detach;
> +
> +__bpf_kfunc int bpf_dummy_do_link_detach(void)
> +{
> + struct bpf_link *link;
> + int ret = -ENOENT;
> +
> + /* A subsystem must ensure that a link is valid when detaching the
> + * link. In order to achieve that, the subsystem may need to obtain
> + * a lock to safeguard a table that holds the pointer to the link
> + * being detached. However, the subsystem cannot invoke
> + * link->ops->detach() while holding the lock because other tasks
> + * may be in the process of unregistering, which could lead to
> + * acquiring the same lock and causing a deadlock. This is why
> + * bpf_link_inc_not_zero() is used to maintain the link's validity.
> + */
> + spin_lock(&detach_lock);
> + link = link_to_detach;
> + /* Make sure the link is still valid by increasing its refcnt */
> + if (link && IS_ERR(bpf_link_inc_not_zero(link)))
> + link = NULL;
> + spin_unlock(&detach_lock);
> +
I know it probably doesn't matter in this example, but where would you set
link_to_detach to NULL if reg and unreg can be called multiple times?
> + if (link) {
> + ret = link->ops->detach(link);
> + bpf_link_put(link);
> + }
> +
> + return ret;
> +}
[...]
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it.
2024-05-21 22:56 ` Amery Hung
@ 2024-05-22 0:31 ` Kui-Feng Lee
2024-05-22 17:33 ` Amery Hung
0 siblings, 1 reply; 16+ messages in thread
From: Kui-Feng Lee @ 2024-05-22 0:31 UTC (permalink / raw
To: Amery Hung, Kui-Feng Lee
Cc: bpf, ast, martin.lau, song, kernel-team, andrii, kuifeng
On 5/21/24 15:56, Amery Hung wrote:
> On Thu, May 09, 2024 at 05:29:41PM -0700, Kui-Feng Lee wrote:
>> Not only a user space program can detach a struct_ops link, the subsystem
>> managing a link can also detach the link. This patch adds a kfunc to
>> simulate detaching a link by the subsystem managing it and makes sure user
>> space programs get notified through epoll.
>>
>> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
>> ---
>> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 42 ++++++++++++
>> .../bpf/bpf_testmod/bpf_testmod_kfunc.h | 1 +
>> .../bpf/prog_tests/test_struct_ops_module.c | 67 +++++++++++++++++++
>> .../selftests/bpf/progs/struct_ops_detach.c | 7 ++
>> 4 files changed, 117 insertions(+)
>>
>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> index 1150e758e630..1f347eed6c18 100644
>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> @@ -741,6 +741,38 @@ __bpf_kfunc int bpf_kfunc_call_kernel_getpeername(struct addr_args *args)
>> return err;
>> }
>>
>> +static DEFINE_SPINLOCK(detach_lock);
>> +static struct bpf_link *link_to_detach;
>> +
>> +__bpf_kfunc int bpf_dummy_do_link_detach(void)
>> +{
>> + struct bpf_link *link;
>> + int ret = -ENOENT;
>> +
>> + /* A subsystem must ensure that a link is valid when detaching the
>> + * link. In order to achieve that, the subsystem may need to obtain
>> + * a lock to safeguard a table that holds the pointer to the link
>> + * being detached. However, the subsystem cannot invoke
>> + * link->ops->detach() while holding the lock because other tasks
>> + * may be in the process of unregistering, which could lead to
>> + * acquiring the same lock and causing a deadlock. This is why
>> + * bpf_link_inc_not_zero() is used to maintain the link's validity.
>> + */
>> + spin_lock(&detach_lock);
>> + link = link_to_detach;
>> + /* Make sure the link is still valid by increasing its refcnt */
>> + if (link && IS_ERR(bpf_link_inc_not_zero(link)))
>> + link = NULL;
>> + spin_unlock(&detach_lock);
>> +
>
> I know it probably doesn't matter in this example, but where would you set
> link_to_detach to NULL if reg and unreg can be called multiple times?
For the same link if there is, reg() can be called only once
except if unreg() has been called for the previous reg() call on the
same link. Unreg() can only be called for once after a reg() call on the
same link.
For struct_ops map with link, unreg() is called by
bpf_struct_ops_map_link_dealloc() and bpf_struct_ops_map_link_detach().
The former one is called for a link only if the refcnt of the link has
dropped to zero. The later one is called for a link only if the refcnt
is not zero, and it holds update_mutex. Once unreg() has been called,
link->map will be cleared as well. So, unreg() should not be called
twice on the same link except it is registered again.
Does that answer your question?
>
>> + if (link) {
>> + ret = link->ops->detach(link);
>> + bpf_link_put(link);
>> + }
>> +
>> + return ret;
>> +}
>
> [...]
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it.
2024-05-22 0:31 ` Kui-Feng Lee
@ 2024-05-22 17:33 ` Amery Hung
0 siblings, 0 replies; 16+ messages in thread
From: Amery Hung @ 2024-05-22 17:33 UTC (permalink / raw
To: Kui-Feng Lee
Cc: Kui-Feng Lee, bpf, ast, martin.lau, song, kernel-team, andrii,
kuifeng
On Tue, May 21, 2024 at 5:31 PM Kui-Feng Lee <sinquersw@gmail.com> wrote:
>
>
>
> On 5/21/24 15:56, Amery Hung wrote:
> > On Thu, May 09, 2024 at 05:29:41PM -0700, Kui-Feng Lee wrote:
> >> Not only a user space program can detach a struct_ops link, the subsystem
> >> managing a link can also detach the link. This patch adds a kfunc to
> >> simulate detaching a link by the subsystem managing it and makes sure user
> >> space programs get notified through epoll.
> >>
> >> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
> >> ---
> >> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 42 ++++++++++++
> >> .../bpf/bpf_testmod/bpf_testmod_kfunc.h | 1 +
> >> .../bpf/prog_tests/test_struct_ops_module.c | 67 +++++++++++++++++++
> >> .../selftests/bpf/progs/struct_ops_detach.c | 7 ++
> >> 4 files changed, 117 insertions(+)
> >>
> >> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> >> index 1150e758e630..1f347eed6c18 100644
> >> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> >> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> >> @@ -741,6 +741,38 @@ __bpf_kfunc int bpf_kfunc_call_kernel_getpeername(struct addr_args *args)
> >> return err;
> >> }
> >>
> >> +static DEFINE_SPINLOCK(detach_lock);
> >> +static struct bpf_link *link_to_detach;
> >> +
> >> +__bpf_kfunc int bpf_dummy_do_link_detach(void)
> >> +{
> >> + struct bpf_link *link;
> >> + int ret = -ENOENT;
> >> +
> >> + /* A subsystem must ensure that a link is valid when detaching the
> >> + * link. In order to achieve that, the subsystem may need to obtain
> >> + * a lock to safeguard a table that holds the pointer to the link
> >> + * being detached. However, the subsystem cannot invoke
> >> + * link->ops->detach() while holding the lock because other tasks
> >> + * may be in the process of unregistering, which could lead to
> >> + * acquiring the same lock and causing a deadlock. This is why
> >> + * bpf_link_inc_not_zero() is used to maintain the link's validity.
> >> + */
> >> + spin_lock(&detach_lock);
> >> + link = link_to_detach;
> >> + /* Make sure the link is still valid by increasing its refcnt */
> >> + if (link && IS_ERR(bpf_link_inc_not_zero(link)))
> >> + link = NULL;
> >> + spin_unlock(&detach_lock);
> >> +
> >
> > I know it probably doesn't matter in this example, but where would you set
> > link_to_detach to NULL if reg and unreg can be called multiple times?
>
> For the same link if there is, reg() can be called only once
> except if unreg() has been called for the previous reg() call on the
> same link. Unreg() can only be called for once after a reg() call on the
> same link.
>
> For struct_ops map with link, unreg() is called by
> bpf_struct_ops_map_link_dealloc() and bpf_struct_ops_map_link_detach().
> The former one is called for a link only if the refcnt of the link has
> dropped to zero. The later one is called for a link only if the refcnt
> is not zero, and it holds update_mutex. Once unreg() has been called,
> link->map will be cleared as well. So, unreg() should not be called
> twice on the same link except it is registered again.
>
> Does that answer your question?
>
Thanks for the detailed explanation. That makes sense to me.
> >
> >> + if (link) {
> >> + ret = link->ops->detach(link);
> >> + bpf_link_put(link);
> >> + }
> >> +
> >> + return ret;
> >> +}
> >
> > [...]
^ permalink raw reply [flat|nested] 16+ messages in thread
end of thread, other threads:[~2024-05-22 17:34 UTC | newest]
Thread overview: 16+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-05-10 0:29 [PATCH bpf-next v3 0/7] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 1/7] bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 2/7] bpf: enable detaching links of struct_ops objects Kui-Feng Lee
2024-05-21 1:22 ` Martin KaFai Lau
2024-05-21 7:30 ` Kui-Feng Lee
2024-05-21 18:09 ` Martin KaFai Lau
2024-05-10 0:29 ` [PATCH bpf-next v3 3/7] bpf: support epoll from bpf struct_ops links Kui-Feng Lee
2024-05-21 1:26 ` Martin KaFai Lau
2024-05-21 7:31 ` Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 4/7] bpf: export bpf_link_inc_not_zero Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 5/7] selftests/bpf: test struct_ops with epoll Kui-Feng Lee
2024-05-10 0:29 ` [PATCH bpf-next v3 6/7] selftests/bpf: detach a struct_ops link from the subsystem managing it Kui-Feng Lee
2024-05-21 22:56 ` Amery Hung
2024-05-22 0:31 ` Kui-Feng Lee
2024-05-22 17:33 ` Amery Hung
2024-05-10 0:29 ` [PATCH bpf-next v3 7/7] selftests/bpf: make sure bpf_testmod handling racing link destroying well Kui-Feng Lee
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