Merge "msm: kgsl: Prevent device start after it is already started" (d362820a) · Commits · e / devices / android_kernel_sony_msm8994

drivers/gpu/msm/adreno.c

+23 −1

Original line number	Diff line number	Diff line
		@@ -1862,6 +1862,8 @@ static int _adreno_start(struct adreno_device *adreno_dev)

		device->reset_counter++;

		set_bit(ADRENO_DEVICE_STARTED, &adreno_dev->priv);

		return 0;

		error_rb_stop:
		@@ -1899,7 +1901,25 @@ static void adreno_start_work(struct work_struct *work)
		set_user_nice(current, _wake_nice);

		mutex_lock(&device->mutex);
		/*
		* If adreno start is already called, no need to call it again
		* it can lead to unpredictable behavior if we try to start
		* the device that is already started.
		* Below is the sequence of events that can go bad without the check
		* 1) thread 1 calls adreno_start to be scheduled on high priority wq
		* 2) thread 2 calls adreno_start with normal priority
		* 3) thread 1 after checking the device to be in slumber state gives
		* up mutex to be scheduled on high priority wq
		* 4) thread 2 after checking the device to be in slumber state gets
		* the mutex and finishes adreno_start before thread 1 is scheduled
		* on high priority wq.
		* 5) thread 1 gets scheduled on high priority wq and executes
		* adreno_start again. This leads to unpredictable behavior.
		*/
		if (!test_bit(ADRENO_DEVICE_STARTED, &adreno_dev->priv))
		_status = _adreno_start(adreno_dev);
		else
		_status = 0;
		mutex_unlock(&device->mutex);
		}

		@@ -1963,6 +1983,8 @@ static int adreno_stop(struct kgsl_device *device)

		kgsl_cffdump_close(device);

		clear_bit(ADRENO_DEVICE_STARTED, &adreno_dev->priv);

		return 0;
		}

+1 −0

Original line number	Diff line number	Diff line
		@@ -206,6 +206,7 @@ enum adreno_device_flags {
		ADRENO_DEVICE_INITIALIZED = 2,
		ADRENO_DEVICE_CORESIGHT = 3,
		ADRENO_DEVICE_HANG_INTR = 4,
		ADRENO_DEVICE_STARTED = 5,
		};

		#define PERFCOUNTER_FLAG_NONE 0x0