* [PATCH v2 0/2] md: simplify md_seq_ops
@ 2023-09-26 2:58 Yu Kuai
2023-09-26 2:58 ` [PATCH v2 1/2] md: factor out a new helper to put mddev Yu Kuai
2023-09-26 2:58 ` [PATCH v2 2/2] md: simplify md_seq_ops Yu Kuai
0 siblings, 2 replies; 9+ messages in thread
From: Yu Kuai @ 2023-09-26 2:58 UTC (permalink / raw
To: mariusz.tkaczyk, xni, song
Cc: linux-raid, linux-kernel, yukuai3, yukuai1, yi.zhang, yangerkun
From: Yu Kuai <yukuai3@huawei.com>
Changes in v2:
- don't hold lock while show mddev in md_seq_show
- add patch 1
- add commit message
Yu Kuai (2):
md: factor out a new helper to put mddev
md: simplify md_seq_ops
drivers/md/md.c | 117 +++++++++++++++---------------------------------
1 file changed, 36 insertions(+), 81 deletions(-)
--
2.39.2
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2 1/2] md: factor out a new helper to put mddev
2023-09-26 2:58 [PATCH v2 0/2] md: simplify md_seq_ops Yu Kuai
@ 2023-09-26 2:58 ` Yu Kuai
2023-09-26 12:45 ` Mariusz Tkaczyk
2023-09-27 0:15 ` Song Liu
2023-09-26 2:58 ` [PATCH v2 2/2] md: simplify md_seq_ops Yu Kuai
1 sibling, 2 replies; 9+ messages in thread
From: Yu Kuai @ 2023-09-26 2:58 UTC (permalink / raw
To: mariusz.tkaczyk, xni, song
Cc: linux-raid, linux-kernel, yukuai3, yukuai1, yi.zhang, yangerkun
From: Yu Kuai <yukuai3@huawei.com>
There are no functional changes, the new helper will still hold
'all_mddevs_lock' after putting mddev, and it will be used to simplify
md_seq_ops.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
drivers/md/md.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 10cb4dfbf4ae..a5ef6f7da8ec 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev *mddev)
static void mddev_delayed_delete(struct work_struct *ws);
-void mddev_put(struct mddev *mddev)
+static void __mddev_put(struct mddev *mddev, bool locked)
{
- if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
+ if (locked) {
+ spin_lock(&all_mddevs_lock);
+ if (!atomic_dec_and_test(&mddev->active))
+ return;
+ } else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
return;
+
if (!mddev->raid_disks && list_empty(&mddev->disks) &&
mddev->ctime == 0 && !mddev->hold_active) {
/* Array is not configured at all, and not held active,
@@ -633,7 +638,14 @@ void mddev_put(struct mddev *mddev)
*/
queue_work(md_misc_wq, &mddev->del_work);
}
- spin_unlock(&all_mddevs_lock);
+
+ if (!locked)
+ spin_unlock(&all_mddevs_lock);
+}
+
+void mddev_put(struct mddev *mddev)
+{
+ __mddev_put(mddev, false);
}
static void md_safemode_timeout(struct timer_list *t);
--
2.39.2
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2 2/2] md: simplify md_seq_ops
2023-09-26 2:58 [PATCH v2 0/2] md: simplify md_seq_ops Yu Kuai
2023-09-26 2:58 ` [PATCH v2 1/2] md: factor out a new helper to put mddev Yu Kuai
@ 2023-09-26 2:58 ` Yu Kuai
2023-09-26 14:09 ` Mariusz Tkaczyk
1 sibling, 1 reply; 9+ messages in thread
From: Yu Kuai @ 2023-09-26 2:58 UTC (permalink / raw
To: mariusz.tkaczyk, xni, song
Cc: linux-raid, linux-kernel, yukuai3, yukuai1, yi.zhang, yangerkun
From: Yu Kuai <yukuai3@huawei.com>
Before this patch, the implementation is hacky and hard to understand:
1) md_seq_start set pos to 1;
2) md_seq_show found pos is 1, then print Personalities;
3) md_seq_next found pos is 1, then it update pos to the first mddev;
4) md_seq_show found pos is not 1 or 2, show mddev;
5) md_seq_next found pos is not 1 or 2, update pos to next mddev;
6) loop 4-5 until the last mddev, then md_seq_next update pos to 2;
7) md_seq_show found pos is 2, then print unused devices;
8) md_seq_next found pos is 2, stop;
This patch remove the magic value and use seq_list_start/next/stop()
directly, and move printing "Personalities" to md_sep_start(),
"unsed devices" to md_seq_stop():
1) md_seq_start print Personalities, and then set pos to first mddev;
2) md_seq_show show mddev;
3) md_seq_next update pos to next mddev;
4) loop 2-3 until the last mddev;
5) md_seq_stop print unsed devices;
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
drivers/md/md.c | 99 +++++++++++--------------------------------------
1 file changed, 21 insertions(+), 78 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index a5ef6f7da8ec..44635b6ee26f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8220,105 +8220,46 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
}
static void *md_seq_start(struct seq_file *seq, loff_t *pos)
+ __acquires(&all_mddevs_lock)
{
- struct list_head *tmp;
- loff_t l = *pos;
- struct mddev *mddev;
+ struct md_personality *pers;
- if (l == 0x10000) {
- ++*pos;
- return (void *)2;
- }
- if (l > 0x10000)
- return NULL;
- if (!l--)
- /* header */
- return (void*)1;
+ seq_puts(seq, "Personalities : ");
+ spin_lock(&pers_lock);
+ list_for_each_entry(pers, &pers_list, list)
+ seq_printf(seq, "[%s] ", pers->name);
+
+ spin_unlock(&pers_lock);
+ seq_puts(seq, "\n");
+ seq->poll_event = atomic_read(&md_event_count);
spin_lock(&all_mddevs_lock);
- list_for_each(tmp,&all_mddevs)
- if (!l--) {
- mddev = list_entry(tmp, struct mddev, all_mddevs);
- if (!mddev_get(mddev))
- continue;
- spin_unlock(&all_mddevs_lock);
- return mddev;
- }
- spin_unlock(&all_mddevs_lock);
- if (!l--)
- return (void*)2;/* tail */
- return NULL;
+
+ return seq_list_start(&all_mddevs, *pos);
}
static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
- struct list_head *tmp;
- struct mddev *next_mddev, *mddev = v;
- struct mddev *to_put = NULL;
-
- ++*pos;
- if (v == (void*)2)
- return NULL;
-
- spin_lock(&all_mddevs_lock);
- if (v == (void*)1) {
- tmp = all_mddevs.next;
- } else {
- to_put = mddev;
- tmp = mddev->all_mddevs.next;
- }
-
- for (;;) {
- if (tmp == &all_mddevs) {
- next_mddev = (void*)2;
- *pos = 0x10000;
- break;
- }
- next_mddev = list_entry(tmp, struct mddev, all_mddevs);
- if (mddev_get(next_mddev))
- break;
- mddev = next_mddev;
- tmp = mddev->all_mddevs.next;
- }
- spin_unlock(&all_mddevs_lock);
-
- if (to_put)
- mddev_put(to_put);
- return next_mddev;
-
+ return seq_list_next(v, &all_mddevs, pos);
}
static void md_seq_stop(struct seq_file *seq, void *v)
+ __releases(&all_mddevs_lock)
{
- struct mddev *mddev = v;
-
- if (mddev && v != (void*)1 && v != (void*)2)
- mddev_put(mddev);
+ status_unused(seq);
+ spin_unlock(&all_mddevs_lock);
}
static int md_seq_show(struct seq_file *seq, void *v)
{
- struct mddev *mddev = v;
+ struct mddev *mddev = list_entry(v, struct mddev, all_mddevs);
sector_t sectors;
struct md_rdev *rdev;
- if (v == (void*)1) {
- struct md_personality *pers;
- seq_printf(seq, "Personalities : ");
- spin_lock(&pers_lock);
- list_for_each_entry(pers, &pers_list, list)
- seq_printf(seq, "[%s] ", pers->name);
-
- spin_unlock(&pers_lock);
- seq_printf(seq, "\n");
- seq->poll_event = atomic_read(&md_event_count);
+ if (!mddev_get(mddev))
return 0;
- }
- if (v == (void*)2) {
- status_unused(seq);
- return 0;
- }
+ spin_unlock(&all_mddevs_lock);
spin_lock(&mddev->lock);
if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
seq_printf(seq, "%s : %sactive", mdname(mddev),
@@ -8390,6 +8331,8 @@ static int md_seq_show(struct seq_file *seq, void *v)
}
spin_unlock(&mddev->lock);
+ __mddev_put(mddev, true);
+
return 0;
}
--
2.39.2
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v2 1/2] md: factor out a new helper to put mddev
2023-09-26 2:58 ` [PATCH v2 1/2] md: factor out a new helper to put mddev Yu Kuai
@ 2023-09-26 12:45 ` Mariusz Tkaczyk
2023-09-26 12:54 ` Yu Kuai
2023-09-27 0:15 ` Song Liu
1 sibling, 1 reply; 9+ messages in thread
From: Mariusz Tkaczyk @ 2023-09-26 12:45 UTC (permalink / raw
To: Yu Kuai; +Cc: xni, song, linux-raid, linux-kernel, yukuai3, yi.zhang, yangerkun
On Tue, 26 Sep 2023 10:58:26 +0800
Yu Kuai <yukuai1@huaweicloud.com> wrote:
> From: Yu Kuai <yukuai3@huawei.com>
>
> There are no functional changes, the new helper will still hold
> 'all_mddevs_lock' after putting mddev, and it will be used to simplify
> md_seq_ops.
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
> drivers/md/md.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 10cb4dfbf4ae..a5ef6f7da8ec 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev
> *mddev)
> static void mddev_delayed_delete(struct work_struct *ws);
>
> -void mddev_put(struct mddev *mddev)
> +static void __mddev_put(struct mddev *mddev, bool locked)
> {
> - if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
> + if (locked) {
> + spin_lock(&all_mddevs_lock);
> + if (!atomic_dec_and_test(&mddev->active))
> + return;
It is "locked" and we are taking lock? It seems weird to me. Perhaps "do_lock"
would be better? Do you meant "lockdep_assert_held(&all_mddevs_lock);"
Something is wrong here, we have two paths and in both cases we are
taking lock.
> + } else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
> return;
> +
> if (!mddev->raid_disks && list_empty(&mddev->disks) &&
> mddev->ctime == 0 && !mddev->hold_active) {
> /* Array is not configured at all, and not held active,
> @@ -633,7 +638,14 @@ void mddev_put(struct mddev *mddev)
> */
> queue_work(md_misc_wq, &mddev->del_work);
> }
> - spin_unlock(&all_mddevs_lock);
> +
> + if (!locked)
> + spin_unlock(&all_mddevs_lock);
As above, I'm not sure if it is correct.
Thanks,
Mariusz
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 1/2] md: factor out a new helper to put mddev
2023-09-26 12:45 ` Mariusz Tkaczyk
@ 2023-09-26 12:54 ` Yu Kuai
2023-09-26 13:19 ` Mariusz Tkaczyk
0 siblings, 1 reply; 9+ messages in thread
From: Yu Kuai @ 2023-09-26 12:54 UTC (permalink / raw
To: Mariusz Tkaczyk, Yu Kuai
Cc: xni, song, linux-raid, linux-kernel, yi.zhang, yangerkun,
yukuai (C)
Hi,
在 2023/09/26 20:45, Mariusz Tkaczyk 写道:
> On Tue, 26 Sep 2023 10:58:26 +0800
> Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> There are no functional changes, the new helper will still hold
>> 'all_mddevs_lock' after putting mddev, and it will be used to simplify
>> md_seq_ops.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>> drivers/md/md.c | 18 +++++++++++++++---
>> 1 file changed, 15 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 10cb4dfbf4ae..a5ef6f7da8ec 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev
>> *mddev)
>> static void mddev_delayed_delete(struct work_struct *ws);
>>
>> -void mddev_put(struct mddev *mddev)
>> +static void __mddev_put(struct mddev *mddev, bool locked)
>> {
>> - if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
>> + if (locked) {
>> + spin_lock(&all_mddevs_lock);
>> + if (!atomic_dec_and_test(&mddev->active))
>> + return;
>
> It is "locked" and we are taking lock? It seems weird to me. Perhaps "do_lock"
> would be better? Do you meant "lockdep_assert_held(&all_mddevs_lock);"
Yes, do_lock is a better name, true means this function will return with
lock held.
>
> Something is wrong here, we have two paths and in both cases we are
> taking lock.
No, in the first path, lock is held unconditionaly, that's what we
expected in md_seq_show(); in the next path, lock will only be held if
active is decreased to 0.
Thanks,
Kuai
>
>> + } else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
>> return;
>> +
>> if (!mddev->raid_disks && list_empty(&mddev->disks) &&
>> mddev->ctime == 0 && !mddev->hold_active) {
>> /* Array is not configured at all, and not held active,
>> @@ -633,7 +638,14 @@ void mddev_put(struct mddev *mddev)
>> */
>> queue_work(md_misc_wq, &mddev->del_work);
>> }
>> - spin_unlock(&all_mddevs_lock);
>> +
>> + if (!locked)
>> + spin_unlock(&all_mddevs_lock);
> As above, I'm not sure if it is correct.
>
> Thanks,
> Mariusz
>
> .
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 1/2] md: factor out a new helper to put mddev
2023-09-26 12:54 ` Yu Kuai
@ 2023-09-26 13:19 ` Mariusz Tkaczyk
0 siblings, 0 replies; 9+ messages in thread
From: Mariusz Tkaczyk @ 2023-09-26 13:19 UTC (permalink / raw
To: Yu Kuai
Cc: xni, song, linux-raid, linux-kernel, yi.zhang, yangerkun,
yukuai (C)
On Tue, 26 Sep 2023 20:54:01 +0800
Yu Kuai <yukuai1@huaweicloud.com> wrote:
> Hi,
>
> 在 2023/09/26 20:45, Mariusz Tkaczyk 写道:
> > On Tue, 26 Sep 2023 10:58:26 +0800
> > Yu Kuai <yukuai1@huaweicloud.com> wrote:
> >
> >> From: Yu Kuai <yukuai3@huawei.com>
> >>
> >> There are no functional changes, the new helper will still hold
> >> 'all_mddevs_lock' after putting mddev, and it will be used to simplify
> >> md_seq_ops.
> >>
> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> >> ---
> >> drivers/md/md.c | 18 +++++++++++++++---
> >> 1 file changed, 15 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/md/md.c b/drivers/md/md.c
> >> index 10cb4dfbf4ae..a5ef6f7da8ec 100644
> >> --- a/drivers/md/md.c
> >> +++ b/drivers/md/md.c
> >> @@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev
> >> *mddev)
> >> static void mddev_delayed_delete(struct work_struct *ws);
> >>
> >> -void mddev_put(struct mddev *mddev)
> >> +static void __mddev_put(struct mddev *mddev, bool locked)
> >> {
> >> - if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
> >> + if (locked) {
> >> + spin_lock(&all_mddevs_lock);
> >> + if (!atomic_dec_and_test(&mddev->active))
> >> + return;
> >
> > It is "locked" and we are taking lock? It seems weird to me. Perhaps
> > "do_lock" would be better? Do you meant
> > "lockdep_assert_held(&all_mddevs_lock);"
>
> Yes, do_lock is a better name, true means this function will return with
> lock held.
> >
> > Something is wrong here, we have two paths and in both cases we are
> > taking lock.
>
> No, in the first path, lock is held unconditionaly, that's what we
> expected in md_seq_show(); in the next path, lock will only be held if
> active is decreased to 0.
>
Ok I see, you described it in commit message.
IMO it is bad practice to return with locked resource and not highlight it in
function name.In this case, I would prefer to respect that device is already
locked, not lock it here:
(assuming bool means "locked")
spin_lock(&all_mddevs_lock);
__mddev_put(mddev, true); <- function known that lock is held.
spin_unlock((mddev);
your "do_lock" approach:
__mddev_put(mddev, true); <- lock is taken here and we are returning
spin_unlock((mddev);
You could change name to something like "all_mddev_lock_and_put(mddev)" to
indicate that we are locking all_mddevs. It fits for me too.
Note: it is just my preference, feel free to ignore :)
Mariusz
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/2] md: simplify md_seq_ops
2023-09-26 2:58 ` [PATCH v2 2/2] md: simplify md_seq_ops Yu Kuai
@ 2023-09-26 14:09 ` Mariusz Tkaczyk
0 siblings, 0 replies; 9+ messages in thread
From: Mariusz Tkaczyk @ 2023-09-26 14:09 UTC (permalink / raw
To: Yu Kuai; +Cc: xni, song, linux-raid, linux-kernel, yukuai3, yi.zhang, yangerkun
On Tue, 26 Sep 2023 10:58:27 +0800
Yu Kuai <yukuai1@huaweicloud.com> wrote:
> From: Yu Kuai <yukuai3@huawei.com>
>
> Before this patch, the implementation is hacky and hard to understand:
>
> 1) md_seq_start set pos to 1;
> 2) md_seq_show found pos is 1, then print Personalities;
> 3) md_seq_next found pos is 1, then it update pos to the first mddev;
> 4) md_seq_show found pos is not 1 or 2, show mddev;
> 5) md_seq_next found pos is not 1 or 2, update pos to next mddev;
> 6) loop 4-5 until the last mddev, then md_seq_next update pos to 2;
> 7) md_seq_show found pos is 2, then print unused devices;
> 8) md_seq_next found pos is 2, stop;
>
> This patch remove the magic value and use seq_list_start/next/stop()
> directly, and move printing "Personalities" to md_sep_start(),
> "unsed devices" to md_seq_stop():
Typo md_sep_start()
>
> 1) md_seq_start print Personalities, and then set pos to first mddev;
> 2) md_seq_show show mddev;
> 3) md_seq_next update pos to next mddev;
> 4) loop 2-3 until the last mddev;
> 5) md_seq_stop print unsed devices;
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
LGTM. Nice one. Code looks much better now.
Reviewed-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 1/2] md: factor out a new helper to put mddev
2023-09-26 2:58 ` [PATCH v2 1/2] md: factor out a new helper to put mddev Yu Kuai
2023-09-26 12:45 ` Mariusz Tkaczyk
@ 2023-09-27 0:15 ` Song Liu
2023-09-27 0:54 ` Yu Kuai
1 sibling, 1 reply; 9+ messages in thread
From: Song Liu @ 2023-09-27 0:15 UTC (permalink / raw
To: Yu Kuai
Cc: mariusz.tkaczyk, xni, linux-raid, linux-kernel, yukuai3, yi.zhang,
yangerkun
On Mon, Sep 25, 2023 at 8:04 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@huawei.com>
>
> There are no functional changes, the new helper will still hold
> 'all_mddevs_lock' after putting mddev, and it will be used to simplify
> md_seq_ops.
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
> drivers/md/md.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 10cb4dfbf4ae..a5ef6f7da8ec 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev *mddev)
>
> static void mddev_delayed_delete(struct work_struct *ws);
>
> -void mddev_put(struct mddev *mddev)
> +static void __mddev_put(struct mddev *mddev, bool locked)
> {
> - if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
> + if (locked) {
> + spin_lock(&all_mddevs_lock);
> + if (!atomic_dec_and_test(&mddev->active))
> + return;
> + } else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
> return;
> +
This condition is indeed very confusing. No matter whether we call the
flag "locked" or "do_lock", it is not really accurate.
How about we factor out a helper with the following logic:
if (!mddev->raid_disks && list_empty(&mddev->disks) &&
mddev->ctime == 0 && !mddev->hold_active) {
/* Array is not configured at all, and not held active,
* so destroy it */
set_bit(MD_DELETED, &mddev->flags);
/*
* Call queue_work inside the spinlock so that
* flush_workqueue() after mddev_find will succeed in waiting
* for the work to be done.
*/
queue_work(md_misc_wq, &mddev->del_work);
}
and then use it at the two callers?
Does this make sense?
Thanks,
Song
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 1/2] md: factor out a new helper to put mddev
2023-09-27 0:15 ` Song Liu
@ 2023-09-27 0:54 ` Yu Kuai
0 siblings, 0 replies; 9+ messages in thread
From: Yu Kuai @ 2023-09-27 0:54 UTC (permalink / raw
To: Song Liu, Yu Kuai
Cc: mariusz.tkaczyk, xni, linux-raid, linux-kernel, yi.zhang,
yangerkun, yukuai (C)
Hi,
在 2023/09/27 8:15, Song Liu 写道:
> On Mon, Sep 25, 2023 at 8:04 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> There are no functional changes, the new helper will still hold
>> 'all_mddevs_lock' after putting mddev, and it will be used to simplify
>> md_seq_ops.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>> drivers/md/md.c | 18 +++++++++++++++---
>> 1 file changed, 15 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 10cb4dfbf4ae..a5ef6f7da8ec 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -616,10 +616,15 @@ static inline struct mddev *mddev_get(struct mddev *mddev)
>>
>> static void mddev_delayed_delete(struct work_struct *ws);
>>
>> -void mddev_put(struct mddev *mddev)
>> +static void __mddev_put(struct mddev *mddev, bool locked)
>> {
>> - if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
>> + if (locked) {
>> + spin_lock(&all_mddevs_lock);
>> + if (!atomic_dec_and_test(&mddev->active))
>> + return;
>> + } else if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
>> return;
>> +
>
> This condition is indeed very confusing. No matter whether we call the
> flag "locked" or "do_lock", it is not really accurate.
>
> How about we factor out a helper with the following logic:
>
> if (!mddev->raid_disks && list_empty(&mddev->disks) &&
> mddev->ctime == 0 && !mddev->hold_active) {
> /* Array is not configured at all, and not held active,
> * so destroy it */
> set_bit(MD_DELETED, &mddev->flags);
>
> /*
> * Call queue_work inside the spinlock so that
> * flush_workqueue() after mddev_find will succeed in waiting
> * for the work to be done.
> */
> queue_work(md_misc_wq, &mddev->del_work);
> }
>
> and then use it at the two callers?
>
> Does this make sense?
Yes, that sounds great. I'll do this in v3.
Thanks,
Kuai
>
> Thanks,
> Song
> .
>
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-09-27 3:00 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-09-26 2:58 [PATCH v2 0/2] md: simplify md_seq_ops Yu Kuai
2023-09-26 2:58 ` [PATCH v2 1/2] md: factor out a new helper to put mddev Yu Kuai
2023-09-26 12:45 ` Mariusz Tkaczyk
2023-09-26 12:54 ` Yu Kuai
2023-09-26 13:19 ` Mariusz Tkaczyk
2023-09-27 0:15 ` Song Liu
2023-09-27 0:54 ` Yu Kuai
2023-09-26 2:58 ` [PATCH v2 2/2] md: simplify md_seq_ops Yu Kuai
2023-09-26 14:09 ` Mariusz Tkaczyk
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