| Message ID | 154295732811.2850.6059970126126914084.stgit@noble (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Assorted lustre patches - mostly from OpenSFS | expand |
> From: Lai Siyao <lai.siyao@intel.com> > > In ll_deauthorize_statahead(), it set thread stop flag, and then > wake up thread, however wakeup is called inside spinlock in case > ll_statahead_info is released, then we need to call smp_mb() to > serialize setting and wakeup. Reviewed-by: James Simmons <jsimmons@infradead.org> > Signed-off-by: Lai Siyao <lai.siyao@intel.com> > WC-bug-id: https://jira.whamcloud.com/browse/LU-7994 > Reviewed-on: https://review.whamcloud.com/23040 > Reviewed-by: Fan Yong <fan.yong@intel.com> > Reviewed-by: Bobi Jam <bobijam@hotmail.com> > Reviewed-by: Oleg Drokin <oleg.drokin@intel.com> > Signed-off-by: NeilBrown <neilb@suse.com> > --- > drivers/staging/lustre/lustre/llite/statahead.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/staging/lustre/lustre/llite/statahead.c b/drivers/staging/lustre/lustre/llite/statahead.c > index 3d71322aa1c7..24c2335c70a7 100644 > --- a/drivers/staging/lustre/lustre/llite/statahead.c > +++ b/drivers/staging/lustre/lustre/llite/statahead.c > @@ -1110,8 +1110,9 @@ static int ll_statahead_thread(void *arg) > sa_handle_callback(sai); > > set_current_state(TASK_IDLE); > + /* ensure we see the NULL stored by ll_deauthorize_statahead() */ > if (!sa_has_callback(sai) && > - sai->sai_task) > + smp_load_acquire(&sai->sai_task)) > schedule(); > __set_current_state(TASK_RUNNING); > } > @@ -1191,9 +1192,17 @@ void ll_deauthorize_statahead(struct inode *dir, void *key) > /* > * statahead thread may not quit yet because it needs to cache > * entries, now it's time to tell it to quit. > + * > + * In case sai is released, wake_up() is called inside spinlock, > + * so we use smp_store_release() to serialize ops. > */ > - wake_up_process(sai->sai_task); > - sai->sai_task = NULL; > + struct task_struct *task = sai->sai_task; > + > + /* ensure ll_statahead_thread sees the NULL before > + * calling schedule() again. > + */ > + smp_store_release(&sai->sai_task, NULL); > + wake_up_process(task); > } > spin_unlock(&lli->lli_sa_lock); > } > > >
diff --git a/drivers/staging/lustre/lustre/llite/statahead.c b/drivers/staging/lustre/lustre/llite/statahead.c index 3d71322aa1c7..24c2335c70a7 100644 --- a/drivers/staging/lustre/lustre/llite/statahead.c +++ b/drivers/staging/lustre/lustre/llite/statahead.c @@ -1110,8 +1110,9 @@ static int ll_statahead_thread(void *arg) sa_handle_callback(sai); set_current_state(TASK_IDLE); + /* ensure we see the NULL stored by ll_deauthorize_statahead() */ if (!sa_has_callback(sai) && - sai->sai_task) + smp_load_acquire(&sai->sai_task)) schedule(); __set_current_state(TASK_RUNNING); } @@ -1191,9 +1192,17 @@ void ll_deauthorize_statahead(struct inode *dir, void *key) /* * statahead thread may not quit yet because it needs to cache * entries, now it's time to tell it to quit. + * + * In case sai is released, wake_up() is called inside spinlock, + * so we use smp_store_release() to serialize ops. */ - wake_up_process(sai->sai_task); - sai->sai_task = NULL; + struct task_struct *task = sai->sai_task; + + /* ensure ll_statahead_thread sees the NULL before + * calling schedule() again. + */ + smp_store_release(&sai->sai_task, NULL); + wake_up_process(task); } spin_unlock(&lli->lli_sa_lock); }