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ocfs2: use spinlock irqsave for downconvert lock.patch 

When ocfs2dc thread holds dc_task_lock spinlock and receives soft IRQ it
deadlock itself trying to get same spinlock in ocfs2_wake_downconvert_thread.
Below is the stack snippet.

The patch disables interrupts when acquiring dc_task_lock spinlock.

	ocfs2_wake_downconvert_thread
	ocfs2_rw_unlock
	ocfs2_dio_end_io
	dio_complete
	.....
	bio_endio
	req_bio_endio
	....
	scsi_io_completion
	blk_done_softirq
	__do_softirq
	do_softirq
	irq_exit
	do_IRQ
	ocfs2_downconvert_thread
	[kthread]

Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Joel Becker <jlbec@evilplan.org>
This commit is contained in:
Srinivas Eeda 2012-01-30 21:51:22 -08:00 committed by Joel Becker
parent 16865b7c42
commit a75e9ccabd
1 changed files with 19 additions and 12 deletions
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31
fs/ocfs2/dlmglue.c
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@ -3932,6 +3932,8 @@ static void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
struct ocfs2_lock_res *lockres)
{
unsigned long flags;
assert_spin_locked(&lockres->l_lock);
if (lockres->l_flags & OCFS2_LOCK_FREEING) {
@ -3945,21 +3947,22 @@ static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
lockres_or_flags(lockres, OCFS2_LOCK_QUEUED);
spin_lock(&osb->dc_task_lock);
spin_lock_irqsave(&osb->dc_task_lock, flags);
if (list_empty(&lockres->l_blocked_list)) {
list_add_tail(&lockres->l_blocked_list,
&osb->blocked_lock_list);
osb->blocked_lock_count++;
}
spin_unlock(&osb->dc_task_lock);
spin_unlock_irqrestore(&osb->dc_task_lock, flags);
}
static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)
{
unsigned long processed;
unsigned long flags;
struct ocfs2_lock_res *lockres;
spin_lock(&osb->dc_task_lock);
spin_lock_irqsave(&osb->dc_task_lock, flags);
/* grab this early so we know to try again if a state change and
* wake happens part-way through our work */
osb->dc_work_sequence = osb->dc_wake_sequence;
@ -3972,38 +3975,40 @@ static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)
struct ocfs2_lock_res, l_blocked_list);
list_del_init(&lockres->l_blocked_list);
osb->blocked_lock_count--;
spin_unlock(&osb->dc_task_lock);
spin_unlock_irqrestore(&osb->dc_task_lock, flags);
BUG_ON(!processed);
processed--;
ocfs2_process_blocked_lock(osb, lockres);
spin_lock(&osb->dc_task_lock);
spin_lock_irqsave(&osb->dc_task_lock, flags);
}
spin_unlock(&osb->dc_task_lock);
spin_unlock_irqrestore(&osb->dc_task_lock, flags);
}
static int ocfs2_downconvert_thread_lists_empty(struct ocfs2_super *osb)
{
int empty = 0;
unsigned long flags;
spin_lock(&osb->dc_task_lock);
spin_lock_irqsave(&osb->dc_task_lock, flags);
if (list_empty(&osb->blocked_lock_list))
empty = 1;
spin_unlock(&osb->dc_task_lock);
spin_unlock_irqrestore(&osb->dc_task_lock, flags);
return empty;
}
static int ocfs2_downconvert_thread_should_wake(struct ocfs2_super *osb)
{
int should_wake = 0;
unsigned long flags;
spin_lock(&osb->dc_task_lock);
spin_lock_irqsave(&osb->dc_task_lock, flags);
if (osb->dc_work_sequence != osb->dc_wake_sequence)
should_wake = 1;
spin_unlock(&osb->dc_task_lock);
spin_unlock_irqrestore(&osb->dc_task_lock, flags);
return should_wake;
}
@ -4033,10 +4038,12 @@ static int ocfs2_downconvert_thread(void *arg)
void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb)
{
spin_lock(&osb->dc_task_lock);
unsigned long flags;
spin_lock_irqsave(&osb->dc_task_lock, flags);
/* make sure the voting thread gets a swipe at whatever changes
* the caller may have made to the voting state */
osb->dc_wake_sequence++;
spin_unlock(&osb->dc_task_lock);
spin_unlock_irqrestore(&osb->dc_task_lock, flags);
wake_up(&osb->dc_event);
}