linux-kernel - [PATCH AUTOSEL 6.6 04/23] scsi: megaraid

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Message-ID: <20241211185214.3841978-4-sashal@kernel.org>
Date: Wed, 11 Dec 2024 13:51:41 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Tomas Henzl <thenzl@...hat.com>,
	Chandrakanth Patil <chandrakanth.patil@...adcom.com>,
	"Martin K . Petersen" <martin.petersen@...cle.com>,
	Sasha Levin <sashal@...nel.org>,
	kashyap.desai@...adcom.com,
	sumit.saxena@...adcom.com,
	shivasharan.srikanteshwara@...adcom.com,
	James.Bottomley@...senPartnership.com,
	megaraidlinux.pdl@...adcom.com,
	linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 04/23] scsi: megaraid_sas: Fix for a potential deadlock

From: Tomas Henzl <thenzl@...hat.com>

[ Upstream commit 50740f4dc78b41dec7c8e39772619d5ba841ddd7 ]

This fixes a 'possible circular locking dependency detected' warning
      CPU0                    CPU1
      ----                    ----
 lock(&instance->reset_mutex);
                              lock(&shost->scan_mutex);
                              lock(&instance->reset_mutex);
 lock(&shost->scan_mutex);

Fix this by temporarily releasing the reset_mutex.

Signed-off-by: Tomas Henzl <thenzl@...hat.com>
Link: https://lore.kernel.org/r/20240923174833.45345-1-thenzl@redhat.com
Acked-by: Chandrakanth Patil <chandrakanth.patil@...adcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/megaraid/megaraid_sas_base.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 3d4f13da1ae87..4cc93cb79b8b0 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -8904,8 +8904,11 @@ megasas_aen_polling(struct work_struct *work)
 						   (ld_target_id / MEGASAS_MAX_DEV_PER_CHANNEL),
 						   (ld_target_id % MEGASAS_MAX_DEV_PER_CHANNEL),
 						   0);
-			if (sdev1)
+			if (sdev1) {
+				mutex_unlock(&instance->reset_mutex);
 				megasas_remove_scsi_device(sdev1);
+				mutex_lock(&instance->reset_mutex);
+			}
 
 			event_type = SCAN_VD_CHANNEL;
 			break;
-- 
2.43.0