msm: kgsl: Fix race condition in adreno_spin_idle()

adreno_spin_idle spins for a timeout checking for gpu to idle. Sometimes due to race conditions the timeout can occur before the loop is executed. Change the logic to a do-while loop and add an extra idle check after the timeout before returning failure. CRs-Fixed: 955055 Change-Id: Idb92a0180dd8cc3e662b1ccf44d69e4bbafb29f1 Signed-off-by: Suman Tatiraju <[email protected]>
kerneltoast · Apr 2, 2016 · 1649034 · 1649034
1 parent 6a055e2
commit 1649034
Showing 1 changed file with 14 additions and 2 deletions.
diff --git a/drivers/gpu/msm/adreno.c b/drivers/gpu/msm/adreno.c
@@ -3024,7 +3024,7 @@ int adreno_idle(struct kgsl_device *device)
 			adreno_getreg(adreno_dev, ADRENO_REG_RBBM_STATUS) << 2,
 			0x110, 0x110);
 
-	while (time_before(jiffies, wait)) {
+	do {
 		/*
 		 * If we fault, stop waiting and return an error. The dispatcher
 		 * will clean up the fault from the work queue, but we need to
@@ -3037,7 +3037,19 @@ int adreno_idle(struct kgsl_device *device)
 
 		if (adreno_isidle(device))
 			return 0;
-	}
+
+	} while (time_before(jiffies, wait));
+
+	/*
+	 * Under rare conditions, preemption can cause the while loop to exit
+	 * without checking if the gpu is idle. check one last time before we
+	 * return failure.
+	 */
+	if (adreno_gpu_fault(adreno_dev) != 0)
+			return -EDEADLK;
+
+	if (adreno_isidle(device))
+			return 0;
 
 	return -ETIMEDOUT;
 }