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From:   gregkh@linuxfoundation.org
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Junlin Yang <yangjunlin@yulong.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.11 036/306] ibmvnic: remove excessive irqsave
Date:   Mon, 15 Mar 2021 14:51:39 +0100
Message-Id: <20210315135508.856738975@linuxfoundation.org>
In-Reply-To: <20210315135507.611436477@linuxfoundation.org>
References: <20210315135507.611436477@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

From: Junlin Yang <yangjunlin@yulong.com>

commit 69cdb7947adb816fc9325b4ec02a6dddd5070b82 upstream.

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@yulong.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/ibm/ibmvnic.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -5474,9 +5474,9 @@ static int ibmvnic_remove(struct vio_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);