[PATCH] megaraid_sas: fix for a potential deadlock

[Tomas Henzl <thenzl@xxxxxxxxxx>]

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 but temporarily releasing the reset_mutex.

Signed-off-by: Tomas Henzl <thenzl@xxxxxxxxxx>
---
 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 6c79c350a4d5..253cc1159661 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -8907,8 +8907,11 @@ 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;
-- 
2.46.0