* [PATCH] btrfs: zstd ensure reclaim timer is properly cleaned up
@ 2019-02-21 20:25 Dennis Zhou
2019-02-22 12:17 ` Nikolay Borisov
0 siblings, 1 reply; 3+ messages in thread
From: Dennis Zhou @ 2019-02-21 20:25 UTC (permalink / raw)
To: David Sterba, Josef Bacik, Chris Mason, Omar Sandoval,
Nick Terrell, Nikolay Borisov
Cc: kernel-team, linux-btrfs, linux-kernel, Dennis Zhou
The timer function, zstd_reclaim_timer_fn(), reschedules itself under
certain conditions. Switch to del_timer_sync() to ensure that the timer
function hasn't rescheduled itself.
Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
fs/btrfs/zstd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 3e418a3aeb11..62de9a211321 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -195,7 +195,7 @@ static void zstd_cleanup_workspace_manager(void)
struct workspace *workspace;
int i;
- del_timer(&wsm.timer);
+ del_timer_sync(&wsm.timer);
for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) {
while (!list_empty(&wsm.idle_ws[i])) {
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] btrfs: zstd ensure reclaim timer is properly cleaned up
2019-02-21 20:25 [PATCH] btrfs: zstd ensure reclaim timer is properly cleaned up Dennis Zhou
@ 2019-02-22 12:17 ` Nikolay Borisov
2019-02-22 16:53 ` Dennis Zhou
0 siblings, 1 reply; 3+ messages in thread
From: Nikolay Borisov @ 2019-02-22 12:17 UTC (permalink / raw)
To: Dennis Zhou, David Sterba, Josef Bacik, Chris Mason,
Omar Sandoval, Nick Terrell
Cc: kernel-team, linux-btrfs, linux-kernel
On 21.02.19 г. 22:25 ч., Dennis Zhou wrote:
> The timer function, zstd_reclaim_timer_fn(), reschedules itself under
> certain conditions. Switch to del_timer_sync() to ensure that the timer
> function hasn't rescheduled itself.
According to del_timer_sync it just waits for any concurrent invocation
to finish. But it's responsibility of the caller to ensure the timer
cannot really be restarted. It's not obvious how
zstd_cleanup_workspace_manager ensures that the timer won't be restared.
Looking at the timer function for it to not restart wsm.lru_list has to
be empty. And seeing that workspace->lru_list is deleted afterwards I'm
not sure this invariant holds.
>
> Signed-off-by: Dennis Zhou <dennis@kernel.org>
> ---
> fs/btrfs/zstd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
> index 3e418a3aeb11..62de9a211321 100644
> --- a/fs/btrfs/zstd.c
> +++ b/fs/btrfs/zstd.c
> @@ -195,7 +195,7 @@ static void zstd_cleanup_workspace_manager(void)
> struct workspace *workspace;
> int i;
>
> - del_timer(&wsm.timer);
> + del_timer_sync(&wsm.timer);
>
> for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) {
> while (!list_empty(&wsm.idle_ws[i])) {
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] btrfs: zstd ensure reclaim timer is properly cleaned up
2019-02-22 12:17 ` Nikolay Borisov
@ 2019-02-22 16:53 ` Dennis Zhou
0 siblings, 0 replies; 3+ messages in thread
From: Dennis Zhou @ 2019-02-22 16:53 UTC (permalink / raw)
To: Nikolay Borisov
Cc: Dennis Zhou, David Sterba, Josef Bacik, Chris Mason,
Omar Sandoval, Nick Terrell, kernel-team, linux-btrfs,
linux-kernel
On Fri, Feb 22, 2019 at 02:17:41PM +0200, Nikolay Borisov wrote:
>
>
> On 21.02.19 г. 22:25 ч., Dennis Zhou wrote:
> > The timer function, zstd_reclaim_timer_fn(), reschedules itself under
> > certain conditions. Switch to del_timer_sync() to ensure that the timer
> > function hasn't rescheduled itself.
>
> According to del_timer_sync it just waits for any concurrent invocation
> to finish. But it's responsibility of the caller to ensure the timer
> cannot really be restarted. It's not obvious how
> zstd_cleanup_workspace_manager ensures that the timer won't be restared.
> Looking at the timer function for it to not restart wsm.lru_list has to
> be empty. And seeing that workspace->lru_list is deleted afterwards I'm
> not sure this invariant holds.
>
Hmmm, I see. I misunderstood the invariant. I'll spin v2 and handle it
another way.
Thanks,
Dennis
> >
> > Signed-off-by: Dennis Zhou <dennis@kernel.org>
> > ---
> > fs/btrfs/zstd.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
> > index 3e418a3aeb11..62de9a211321 100644
> > --- a/fs/btrfs/zstd.c
> > +++ b/fs/btrfs/zstd.c
> > @@ -195,7 +195,7 @@ static void zstd_cleanup_workspace_manager(void)
> > struct workspace *workspace;
> > int i;
> >
> > - del_timer(&wsm.timer);
> > + del_timer_sync(&wsm.timer);
> >
> > for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) {
> > while (!list_empty(&wsm.idle_ws[i])) {
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-02-22 16:54 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-02-21 20:25 [PATCH] btrfs: zstd ensure reclaim timer is properly cleaned up Dennis Zhou
2019-02-22 12:17 ` Nikolay Borisov
2019-02-22 16:53 ` Dennis Zhou
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).