linux-kernel - [PATCH v1] ibmvnic: remove excessive irqsave

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Date:   Fri,  5 Mar 2021 16:48:39 +0800
From:   angkery <angkery@....com>
To:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        drt@...ux.ibm.com, ljp@...ux.ibm.com, sukadev@...ux.ibm.com,
        davem@...emloft.net, kuba@...nel.org
Cc:     linuxppc-dev@...ts.ozlabs.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Junlin Yang <yangjunlin@...ong.com>
Subject: [PATCH v1] ibmvnic: remove excessive irqsave

From: Junlin Yang <yangjunlin@...ong.com>

ibmvnic_remove locks multiple spinlocks while disabling interrupts:
spin_lock_irqsave(&adapter->state_lock, flags);
spin_lock_irqsave(&adapter->rwi_lock, flags);

As reported by coccinelle, 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. So remove the second
_irqsave():
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.

Fixes: 4a41c421f367 ("ibmvnic: serialize access to work queue on remove")
Signed-off-by: Junlin Yang <yangjunlin@...ong.com>
---
Changes in v1:
	a.According to Christophe Leroy's explanation, update the commit information.
	b.Add fixes tags.

 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);
 
-- 
1.9.1