From: "tip-bot2 for Mike Galbraith" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>, x86 <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: [tip: locking/core] connector/cn_proc: Protect send_msg() with a local lock
Date: Mon, 01 Jun 2020 09:52:31 -0000 [thread overview]
Message-ID: <159100515158.17951.5876738878274408032.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20200527201119.1692513-6-bigeasy@linutronix.de>
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 3e92fd7bd2b8418b53cb7304855b8b69bedbe2b4
Gitweb: https://git.kernel.org/tip/3e92fd7bd2b8418b53cb7304855b8b69bedbe2b4
Author: Mike Galbraith <umgwanakikbuti@gmail.com>
AuthorDate: Wed, 27 May 2020 22:11:17 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Thu, 28 May 2020 10:31:10 +02:00
connector/cn_proc: Protect send_msg() with a local lock
send_msg() disables preemption to avoid out-of-order messages. As the
code inside the preempt disabled section acquires regular spinlocks,
which are converted to 'sleeping' spinlocks on a PREEMPT_RT kernel and
eventually calls into a memory allocator, this conflicts with the RT
semantics.
Convert it to a local_lock which allows RT kernels to substitute them with
a real per CPU lock. On non RT kernels this maps to preempt_disable() as
before. No functional change.
[bigeasy: Patch description]
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20200527201119.1692513-6-bigeasy@linutronix.de
---
drivers/connector/cn_proc.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index d58ce66..646ad38 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -18,6 +18,7 @@
#include <linux/pid_namespace.h>
#include <linux/cn_proc.h>
+#include <linux/local_lock.h>
/*
* Size of a cn_msg followed by a proc_event structure. Since the
@@ -38,25 +39,31 @@ static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
-/* proc_event_counts is used as the sequence number of the netlink message */
-static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
+/* local_event.count is used as the sequence number of the netlink message */
+struct local_event {
+ local_lock_t lock;
+ __u32 count;
+};
+static DEFINE_PER_CPU(struct local_event, local_event) = {
+ .lock = INIT_LOCAL_LOCK(lock),
+};
static inline void send_msg(struct cn_msg *msg)
{
- preempt_disable();
+ local_lock(&local_event.lock);
- msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
+ msg->seq = __this_cpu_inc_return(local_event.count) - 1;
((struct proc_event *)msg->data)->cpu = smp_processor_id();
/*
- * Preemption remains disabled during send to ensure the messages are
- * ordered according to their sequence numbers.
+ * local_lock() disables preemption during send to ensure the messages
+ * are ordered according to their sequence numbers.
*
* If cn_netlink_send() fails, the data is not sent.
*/
cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
- preempt_enable();
+ local_unlock(&local_event.lock);
}
void proc_fork_connector(struct task_struct *task)
next prev parent reply other threads:[~2020-06-01 9:53 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 20:11 [PATCH v3 0/7] Introduce local_lock() Sebastian Andrzej Siewior
2020-05-27 20:11 ` [PATCH v3 1/7] locking: " Sebastian Andrzej Siewior
2020-06-01 9:52 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-05-27 20:11 ` [PATCH v3 2/7] radix-tree: Use local_lock for protection Sebastian Andrzej Siewior
2020-06-01 9:52 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-05-27 20:11 ` [PATCH v3 3/7] mm/swap: " Sebastian Andrzej Siewior
2020-06-01 9:52 ` [tip: locking/core] " tip-bot2 for Ingo Molnar
2020-05-27 20:11 ` [PATCH v3 4/7] squashfs: make use of local lock in multi_cpu decompressor Sebastian Andrzej Siewior
2020-06-01 9:52 ` [tip: locking/core] squashfs: Make " tip-bot2 for Julia Cartwright
2020-05-27 20:11 ` [PATCH v3 5/7] connector/cn_proc: Protect send_msg() with a local lock Sebastian Andrzej Siewior
2020-06-01 9:52 ` tip-bot2 for Mike Galbraith [this message]
2020-05-27 20:11 ` [PATCH v3 6/7] zram: Allocate struct zcomp_strm as per-CPU memory Sebastian Andrzej Siewior
2020-05-29 20:51 ` Minchan Kim
2020-06-01 9:52 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-05-27 20:11 ` [PATCH v3 7/7] zram: Use local lock to protect per-CPU data Sebastian Andrzej Siewior
2020-05-29 20:57 ` Minchan Kim
2020-06-01 9:52 ` [tip: locking/core] " tip-bot2 for Mike Galbraith
2020-10-19 1:52 ` [PATCH v3 7/7] " Yu Zhao
2020-10-19 2:33 ` Hugh Dickins
2020-10-19 2:46 ` Mike Galbraith
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