Re: [PATCH] ibmvnic: remove excessive irqsave
From: Christophe Leroy <hidden>
Date: 2021-03-05 05:49:38
Also in:
linuxppc-dev, lkml
Le 05/03/2021 à 02:43, angkery a écrit :
From: Junlin Yang <redacted> ibmvnic_remove locks multiple spinlocks while disabling interrupts: spin_lock_irqsave(&adapter->state_lock, flags); spin_lock_irqsave(&adapter->rwi_lock, flags); there is no need for the second irqsave,since interrupts are disabled at that point, so remove the second irqsave:
The problème is not that there is no need. The problem is a lot more serious: As reported by coccinella, the second _irqsave() overwrites the value saved in 'flags' by the first _irqsave, therefore when the second _irqrestore comes, the value in 'flags' is not valid, the value saved by the first _irqsave has been lost. This likely leads to IRQs remaining disabled, which is _THE_ problem really.
quoted hunk ↗ jump to hunk
spin_lock_irqsave(&adapter->state_lock, flags); spin_lock(&adapter->rwi_lock); Generated by: ./scripts/coccinelle/locks/flags.cocci ./drivers/net/ethernet/ibm/ibmvnic.c:5413:1-18: ERROR: nested lock+irqsave that reuses flags from line 5404. Signed-off-by: Junlin Yang <redacted> --- drivers/net/ethernet/ibm/ibmvnic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c index 2464c8a..a52668d 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.c +++ b/drivers/net/ethernet/ibm/ibmvnic.c@@ -5408,9 +5408,9 @@ static void ibmvnic_remove(struct vio_dev *dev) * after setting state, so __ibmvnic_reset() which is called * from the flush_work() below, can make progress. */ - spin_lock_irqsave(&adapter->rwi_lock, flags); + spin_lock(&adapter->rwi_lock); adapter->state = VNIC_REMOVING; - spin_unlock_irqrestore(&adapter->rwi_lock, flags); + spin_unlock(&adapter->rwi_lock); spin_unlock_irqrestore(&adapter->state_lock, flags);