[PATCH 2/2] scsi: mpt3sas: Fix a locking bug in an error path

[Bart Van Assche <bvanassche@acm.org>]

Call mutex_unlock(&ioc->hostdiag_unlock_mutex) once from error paths
instead of twice.

This patch fixes the following Clang -Wthread-safety errors:

drivers/scsi/mpt3sas/mpt3sas_base.c:8085:2: error: mutex 'ioc->hostdiag_unlock_mutex' is not held on every path through here [-Werror,-Wthread-safety-analysis]
 8085 |         pci_cfg_access_unlock(ioc->pdev);
      |         ^
drivers/scsi/mpt3sas/mpt3sas_base.c:8019:2: note: mutex acquired here
 8019 |         mutex_lock(&ioc->hostdiag_unlock_mutex);
      |         ^
./include/linux/mutex.h:171:26: note: expanded from macro 'mutex_lock'
  171 | #define mutex_lock(lock) mutex_lock_nested(lock, 0)
      |                          ^
drivers/scsi/mpt3sas/mpt3sas_base.c:8085:2: error: mutex 'ioc->hostdiag_unlock_mutex' is not held on every path through here [-Werror,-Wthread-safety-analysis]
 8085 |         pci_cfg_access_unlock(ioc->pdev);
      |         ^
drivers/scsi/mpt3sas/mpt3sas_base.c:8019:2: note: mutex acquired here
 8019 |         mutex_lock(&ioc->hostdiag_unlock_mutex);
      |         ^
./include/linux/mutex.h:171:26: note: expanded from macro 'mutex_lock'
  171 | #define mutex_lock(lock) mutex_lock_nested(lock, 0)
      |                          ^
drivers/scsi/mpt3sas/mpt3sas_base.c:8087:2: error: releasing mutex 'ioc->hostdiag_unlock_mutex' that was not held [-Werror,-Wthread-safety-analysis]
 8087 |         mutex_unlock(&ioc->hostdiag_unlock_mutex);
      |         ^

Cc: Ranjan Kumar <ranjan.kumar@broadcom.com>
Fixes: c0767560b012 ("scsi: mpt3sas: Reload SBR without rebooting HBA")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/mpt3sas/mpt3sas_base.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index dc43cfa83088..212e3b86bb81 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -8018,7 +8018,7 @@ _base_diag_reset(struct MPT3SAS_ADAPTER *ioc)
 
 	mutex_lock(&ioc->hostdiag_unlock_mutex);
 	if (mpt3sas_base_unlock_and_get_host_diagnostic(ioc, &host_diagnostic))
-		goto out;
+		goto unlock;
 
 	hcb_size = ioc->base_readl(&ioc->chip->HCBSize);
 	drsprintk(ioc, ioc_info(ioc, "diag reset: issued\n"));
@@ -8038,7 +8038,7 @@ _base_diag_reset(struct MPT3SAS_ADAPTER *ioc)
 			ioc_info(ioc,
 			    "Invalid host diagnostic register value\n");
 			_base_dump_reg_set(ioc);
-			goto out;
+			goto unlock;
 		}
 		if (!(host_diagnostic & MPI2_DIAG_RESET_ADAPTER))
 			break;
@@ -8074,17 +8074,19 @@ _base_diag_reset(struct MPT3SAS_ADAPTER *ioc)
 		ioc_err(ioc, "%s: failed going to ready state (ioc_state=0x%x)\n",
 			__func__, ioc_state);
 		_base_dump_reg_set(ioc);
-		goto out;
+		goto fail;
 	}
 
 	pci_cfg_access_unlock(ioc->pdev);
 	ioc_info(ioc, "diag reset: SUCCESS\n");
 	return 0;
 
- out:
+unlock:
+	mutex_unlock(&ioc->hostdiag_unlock_mutex);
+
+fail:
 	pci_cfg_access_unlock(ioc->pdev);
 	ioc_err(ioc, "diag reset: FAILED\n");
-	mutex_unlock(&ioc->hostdiag_unlock_mutex);
 	return -EFAULT;
 }