v4l2_m2m_job_finish() is typically called in interrupt context.
Some implementation of .device_run might sleep, and so it's
desirable to avoid calling it directly from
v4l2_m2m_job_finish(), thus avoiding .device_run from running
in interrupt context.
Implement a deferred context that calls v4l2_m2m_try_run,
and gets scheduled by v4l2_m2m_job_finish().
Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-mem2mem.c | 46 +++++++++++++++++++++++---
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 04e2c8357863..020b2d8621d0 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -69,6 +69,7 @@ static const char * const m2m_entity_name[] = {
* @curr_ctx: currently running instance
* @job_queue: instances queued to run
* @job_spinlock: protects job_queue
+ * @job_work: worker to run queued jobs.
* @m2m_ops: driver callbacks
*/
struct v4l2_m2m_dev {
@@ -85,6 +86,7 @@ struct v4l2_m2m_dev {
struct list_head job_queue;
spinlock_t job_spinlock;
+ struct work_struct job_work;
const struct v4l2_m2m_ops *m2m_ops;
};
@@ -224,10 +226,11 @@ EXPORT_SYMBOL(v4l2_m2m_get_curr_priv);
/**
* v4l2_m2m_try_run() - select next job to perform and run it if possible
* @m2m_dev: per-device context
+ * @try_lock: indicates if the queue lock should be taken
*
* Get next transaction (if present) from the waiting jobs list and run it.
*/
-static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
+static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev, bool try_lock)
{
unsigned long flags;
@@ -250,7 +253,20 @@ static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
dprintk("Running job on m2m_ctx: %p\n", m2m_dev->curr_ctx);
+
+ /*
+ * A m2m context lock is taken only after a m2m context
+ * is picked from the queue and marked as running.
+ * The lock is only needed if v4l2_m2m_try_run is called
+ * from the async worker.
+ */
+ if (try_lock && m2m_dev->curr_ctx->q_lock)
+ mutex_lock(m2m_dev->curr_ctx->q_lock);
+
m2m_dev->m2m_ops->device_run(m2m_dev->curr_ctx->priv);
+
+ if (try_lock && m2m_dev->curr_ctx->q_lock)
+ mutex_unlock(m2m_dev->curr_ctx->q_lock);
}
/*
@@ -330,7 +346,8 @@ static void __v4l2_m2m_try_queue(struct v4l2_m2m_dev *m2m_dev,
* Check if this context is ready to queue a job. If suitable,
* run the next queued job on the mem2mem device.
*
- * This function shouldn't run in interrupt context.
+ * This function shouldn't run in interrupt context, and must be called
+ * with the v4l2_m2m_ctx.q_lock mutex held.
*
* Note that v4l2_m2m_try_schedule() can schedule one job for this context,
* and then run another job for another context.
@@ -339,11 +356,26 @@ void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
{
struct v4l2_m2m_dev *m2m_dev = m2m_ctx->m2m_dev;
+ if (m2m_ctx->q_lock)
+ WARN_ON(!mutex_is_locked(m2m_ctx->q_lock));
+
__v4l2_m2m_try_queue(m2m_dev, m2m_ctx);
- v4l2_m2m_try_run(m2m_dev);
+ v4l2_m2m_try_run(m2m_dev, false);
}
EXPORT_SYMBOL_GPL(v4l2_m2m_try_schedule);
+/**
+ * v4l2_m2m_device_run_work() - run pending jobs for the context
+ * @work: Work structure used for scheduling the execution of this function.
+ */
+static void v4l2_m2m_device_run_work(struct work_struct *work)
+{
+ struct v4l2_m2m_dev *m2m_dev =
+ container_of(work, struct v4l2_m2m_dev, job_work);
+
+ v4l2_m2m_try_run(m2m_dev, true);
+}
+
/**
* v4l2_m2m_cancel_job() - cancel pending jobs for the context
* @m2m_ctx: m2m context with jobs to be canceled
@@ -403,7 +435,12 @@ void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
/* This instance might have more buffers ready, but since we do not
* allow more than one job on the job_queue per instance, each has
* to be scheduled separately after the previous one finishes. */
- v4l2_m2m_try_schedule(m2m_ctx);
+ __v4l2_m2m_try_queue(m2m_dev, m2m_ctx);
+
+ /* We might be running in atomic context,
+ * but the job must be run in non-atomic context.
+ */
+ schedule_work(&m2m_dev->job_work);
}
EXPORT_SYMBOL(v4l2_m2m_job_finish);
@@ -837,6 +874,7 @@ struct v4l2_m2m_dev *v4l2_m2m_init(const struct v4l2_m2m_ops *m2m_ops)
m2m_dev->m2m_ops = m2m_ops;
INIT_LIST_HEAD(&m2m_dev->job_queue);
spin_lock_init(&m2m_dev->job_spinlock);
+ INIT_WORK(&m2m_dev->job_work, v4l2_m2m_device_run_work);
return m2m_dev;
}
--
2.18.0
