msm: adsprpc: Fix race condition in internal_control

Protect add and update qos request with mutex to
avoid race condition when multiple threads try to add
or update request simultaneously.

Change-Id: Id33b81bf85246ec69c72bad59cca068e627bb21d
Acked-by: Deepika Singh <[email protected]>
Signed-off-by: Jeya R <[email protected]>

drivers/char/adsprpc.c

@@ -392,6 +392,7 @@ struct fastrpc_file {
 	struct mutex perf_mutex;
 	struct pm_qos_request pm_qos_req;
 	int qos_request;
+	struct mutex pm_qos_mutex;
 	struct mutex map_mutex;
 	struct mutex internal_map_mutex;
 	/* Identifies the device (MINOR_NUM_DEV / MINOR_NUM_SECURE_DEV) */
@@ -3078,6 +3079,7 @@ static int fastrpc_file_free(struct fastrpc_file *fl)
 	mutex_destroy(&fl->perf_mutex);
 	mutex_destroy(&fl->map_mutex);
 	mutex_destroy(&fl->internal_map_mutex);
+	mutex_destroy(&fl->pm_qos_mutex);
 	kfree(fl);
 	return 0;
 }
@@ -3426,6 +3428,7 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
 	hlist_add_head(&fl->hn, &me->drivers);
 	spin_unlock(&me->hlock);
 	mutex_init(&fl->perf_mutex);
+	mutex_init(&fl->pm_qos_mutex);
 	return 0;
 }
 
@@ -3539,12 +3542,14 @@ static int fastrpc_internal_control(struct fastrpc_file *fl,
 		VERIFY(err, latency != 0);
 		if (err)
 			goto bail;
+		mutex_lock(&fl->pm_qos_mutex);
 		if (!fl->qos_request) {
 			pm_qos_add_request(&fl->pm_qos_req,
 				PM_QOS_CPU_DMA_LATENCY, latency);
 			fl->qos_request = 1;
 		} else
 			pm_qos_update_request(&fl->pm_qos_req, latency);
+		mutex_unlock(&fl->pm_qos_mutex);
 		break;
 	case FASTRPC_CONTROL_KALLOC:
 		cp->kalloc.kalloc_support = 1;