[PATCH v2 05/18] megaraid_sas: Release Mutex lock before OCR in case of DCMD timeout

[Chandrakanth Patil <chandrakanth.patil@xxxxxxxxxxxx>]

Issue: There is possibility of few DCMDs timing out with 'reset_mutex'
lock held. As part of DCMD timeout handling, driver calls function
megasas_reset_fusion which also tries to acquire same lock 'reset_mutex'
and end up with deadlock.

Fix: Upon timeout of DCMDs(which are fired with 'reset_mutex' lock held),
driver will release 'reset_mutex' before calling OCR function and will
acquire lock again after OCR function returns.

Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@xxxxxxxxxxxx>
---
 drivers/scsi/megaraid/megaraid_sas_base.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 7d1cf4e..54bb48e 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -4369,8 +4369,10 @@ megasas_get_pd_info(struct megasas_instance *instance, struct scsi_device *sdev)
 		switch (dcmd_timeout_ocr_possible(instance)) {
 		case INITIATE_OCR:
 			cmd->flags |= DRV_DCMD_SKIP_REFIRE;
+			mutex_unlock(&instance->reset_mutex);
 			megasas_reset_fusion(instance->host,
 				MFI_IO_TIMEOUT_OCR);
+			mutex_lock(&instance->reset_mutex);
 			break;
 		case KILL_ADAPTER:
 			megaraid_sas_kill_hba(instance);
@@ -4861,8 +4863,10 @@ megasas_host_device_list_query(struct megasas_instance *instance,
 		switch (dcmd_timeout_ocr_possible(instance)) {
 		case INITIATE_OCR:
 			cmd->flags |= DRV_DCMD_SKIP_REFIRE;
+			mutex_unlock(&instance->reset_mutex);
 			megasas_reset_fusion(instance->host,
 				MFI_IO_TIMEOUT_OCR);
+			mutex_lock(&instance->reset_mutex);
 			break;
 		case KILL_ADAPTER:
 			megaraid_sas_kill_hba(instance);
@@ -5010,8 +5014,10 @@ void megasas_get_snapdump_properties(struct megasas_instance *instance)
 		switch (dcmd_timeout_ocr_possible(instance)) {
 		case INITIATE_OCR:
 			cmd->flags |= DRV_DCMD_SKIP_REFIRE;
+			mutex_unlock(&instance->reset_mutex);
 			megasas_reset_fusion(instance->host,
 				MFI_IO_TIMEOUT_OCR);
+			mutex_lock(&instance->reset_mutex);
 			break;
 		case KILL_ADAPTER:
 			megaraid_sas_kill_hba(instance);
@@ -5141,8 +5147,10 @@ megasas_get_ctrl_info(struct megasas_instance *instance)
 		switch (dcmd_timeout_ocr_possible(instance)) {
 		case INITIATE_OCR:
 			cmd->flags |= DRV_DCMD_SKIP_REFIRE;
+			mutex_unlock(&instance->reset_mutex);
 			megasas_reset_fusion(instance->host,
 				MFI_IO_TIMEOUT_OCR);
+			mutex_lock(&instance->reset_mutex);
 			break;
 		case KILL_ADAPTER:
 			megaraid_sas_kill_hba(instance);
@@ -6398,8 +6406,10 @@ megasas_get_target_prop(struct megasas_instance *instance,
 		switch (dcmd_timeout_ocr_possible(instance)) {
 		case INITIATE_OCR:
 			cmd->flags |= DRV_DCMD_SKIP_REFIRE;
+			mutex_unlock(&instance->reset_mutex);
 			megasas_reset_fusion(instance->host,
 					     MFI_IO_TIMEOUT_OCR);
+			mutex_lock(&instance->reset_mutex);
 			break;
 		case KILL_ADAPTER:
 			megaraid_sas_kill_hba(instance);
@@ -7801,10 +7811,13 @@ megasas_mgmt_fw_ioctl(struct megasas_instance *instance,
 		opcode = le32_to_cpu(cmd->frame->dcmd.opcode);
 
 	if (opcode == MR_DCMD_CTRL_SHUTDOWN) {
+		mutex_lock(&instance->reset_mutex);
 		if (megasas_get_ctrl_info(instance) != DCMD_SUCCESS) {
 			megasas_return_cmd(instance, cmd);
+			mutex_unlock(&instance->reset_mutex);
 			return -1;
 		}
+		mutex_unlock(&instance->reset_mutex);
 	}
 
 	if (opcode == MR_DRIVER_SET_APP_CRASHDUMP_MODE) {
-- 
2.9.5