Commit "7ea7e98fd8d0" suggests that the "pci_lock" is sufficient,
and all the callers of pci_wait_cfg() are wrapped with the "pci_lock".
However, since the commit "cdcb33f98244" merged, the accesses to
the pci_cfg_wait queue are not safe anymore. A "pci_lock" is
insufficient and we need to hold an additional queue lock while
read/write the wait queue.
So let's use the add_wait_queue()/remove_wait_queue() instead of
__add_wait_queue()/__remove_wait_queue(). Also move the wait queue
functionality around the "schedule()" function to avoid reintroducing
the deadlock addressed by "cdcb33f98244".
Signed-off-by: Xiang Zheng <zhengxiang9@xxxxxxxxxx>
Cc: Heyi Guo <guoheyi@xxxxxxxxxx>
Cc: Biaoxiang Ye <yebiaoxiang@xxxxxxxxxx>
---
v2:
- Move the wait queue functionality around the "schedule()" function to
avoid reintroducing the deadlock addressed by "cdcb33f98244"
---
drivers/pci/access.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 2fccb5762c76..09342a74e5ea 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -207,14 +207,14 @@ static noinline void pci_wait_cfg(struct pci_dev *dev)
{
DECLARE_WAITQUEUE(wait, current);
- __add_wait_queue(&pci_cfg_wait, &wait);
do {
set_current_state(TASK_UNINTERRUPTIBLE);
raw_spin_unlock_irq(&pci_lock);
+ add_wait_queue(&pci_cfg_wait, &wait);
schedule();
+ remove_wait_queue(&pci_cfg_wait, &wait);
raw_spin_lock_irq(&pci_lock);
} while (dev->block_cfg_access);
- __remove_wait_queue(&pci_cfg_wait, &wait);
}
/* Returns 0 on success, negative values indicate error. */
--
2.19.1
