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authorSebastian Ott <sebott@linux.vnet.ibm.com>2014-06-05 16:30:19 +0400
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2014-06-10 12:48:30 +0400
commit0eb69a0c584d0eaec6c2b6663e03184625c3517b (patch)
treeb12bec17e1646166bdbf96ab617c794e7edad6c2 /drivers/s390
parent646f919e93d4371b8654c4ae801aee74a00e4a68 (diff)
downloadlinux-0eb69a0c584d0eaec6c2b6663e03184625c3517b.tar.xz
s390/airq: silence lockdep warning
airq_iv_(alloc|free) is called by some users with interrupts enabled and by some with interrupts disabled which leads to the following lockdep warning: [ INFO: possible irq lock inversion dependency detected ] 3.14.0-15249-gbf29b7b-dirty #25 Not tainted --------------------------------------------------------- insmod/2108 just changed the state of lock: (&(&iv->lock)->rlock){+.....}, at: [<000000000046ee3e>] airq_iv_alloc+0x62/0x228 but this lock was taken by another, HARDIRQ-READ-safe lock in the past: (&info->lock){.-.-..} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&iv->lock)->rlock); local_irq_disable(); lock(&info->lock); lock(&(&iv->lock)->rlock); <Interrupt> lock(&info->lock); *** DEADLOCK *** Although this is a false alarm (since each airq user consistently calls these functions from the same context) fix this by ensuring that interrupts are disabled when the airq lock is held. Reported-by: Frank Blaschka <frank.blaschka@de.ibm.com> Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/cio/airq.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index 445564c790f6..00bfbee0af9e 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -196,11 +196,11 @@ EXPORT_SYMBOL(airq_iv_release);
*/
unsigned long airq_iv_alloc(struct airq_iv *iv, unsigned long num)
{
- unsigned long bit, i;
+ unsigned long bit, i, flags;
if (!iv->avail || num == 0)
return -1UL;
- spin_lock(&iv->lock);
+ spin_lock_irqsave(&iv->lock, flags);
bit = find_first_bit_inv(iv->avail, iv->bits);
while (bit + num <= iv->bits) {
for (i = 1; i < num; i++)
@@ -218,9 +218,8 @@ unsigned long airq_iv_alloc(struct airq_iv *iv, unsigned long num)
}
if (bit + num > iv->bits)
bit = -1UL;
- spin_unlock(&iv->lock);
+ spin_unlock_irqrestore(&iv->lock, flags);
return bit;
-
}
EXPORT_SYMBOL(airq_iv_alloc);
@@ -232,11 +231,11 @@ EXPORT_SYMBOL(airq_iv_alloc);
*/
void airq_iv_free(struct airq_iv *iv, unsigned long bit, unsigned long num)
{
- unsigned long i;
+ unsigned long i, flags;
if (!iv->avail || num == 0)
return;
- spin_lock(&iv->lock);
+ spin_lock_irqsave(&iv->lock, flags);
for (i = 0; i < num; i++) {
/* Clear (possibly left over) interrupt bit */
clear_bit_inv(bit + i, iv->vector);
@@ -248,7 +247,7 @@ void airq_iv_free(struct airq_iv *iv, unsigned long bit, unsigned long num)
while (iv->end > 0 && !test_bit_inv(iv->end - 1, iv->avail))
iv->end--;
}
- spin_unlock(&iv->lock);
+ spin_unlock_irqrestore(&iv->lock, flags);
}
EXPORT_SYMBOL(airq_iv_free);