linux-kernel - [PATCH v2] dmaengine: idxd: avoid deadlock in process_misc

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Message-Id: <20220823163709.2102468-1-jsnitsel@redhat.com>
Date:   Tue, 23 Aug 2022 09:37:09 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org
Subject: [PATCH v2] dmaengine: idxd: avoid deadlock in process_misc_interrupts()

idxd_device_clear_state() now grabs the idxd->dev_lock
itself, so don't grab the lock prior to calling it.

This was seen in testing after dmar fault occurred on system,
resulting in lockup stack traces.

Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Vinod Koul <vkoul@...nel.org>
Cc: dmaengine@...r.kernel.org
Fixes: cf4ac3fef338 ("dmaengine: idxd: fix lockdep warning on device driver removal")
Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
---
v2: add Fixes tag, and add subsystem to summary

 drivers/dma/idxd/irq.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
index 743ead5ebc57..5b9921475be6 100644
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -324,13 +324,11 @@ static int process_misc_interrupts(struct idxd_device *idxd, u32 cause)
 			idxd->state = IDXD_DEV_HALTED;
 			idxd_wqs_quiesce(idxd);
 			idxd_wqs_unmap_portal(idxd);
-			spin_lock(&idxd->dev_lock);
 			idxd_device_clear_state(idxd);
 			dev_err(&idxd->pdev->dev,
 				"idxd halted, need %s.\n",
 				gensts.reset_type == IDXD_DEVICE_RESET_FLR ?
 				"FLR" : "system reset");
-			spin_unlock(&idxd->dev_lock);
 			return -ENXIO;
 		}
 	}
-- 
2.37.2