| Message ID | 20190221202556.42447-1-dennis@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: zstd ensure reclaim timer is properly cleaned up | expand |
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])) { >
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])) { > >
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])) {
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(-)