Commit 9db3bbf5 authored by Ezequiel Garcia's avatar Ezequiel Garcia Committed by Mauro Carvalho Chehab
Browse files

media: v4l2-mem2mem: Fix missing v4l2_m2m_try_run call 



Commit 34dbb848 ("media: mem2mem: Remove excessive try_run call")
removed a redundant call to v4l2_m2m_try_run but instead introduced
a bug. Consider the following case:

 1) Context A schedules, queues and runs job A.
 2) While the m2m device is running, context B schedules
    and queues job B. Job B cannot run, because it has to
    wait for job A.
 3) Job A completes, calls v4l2_m2m_job_finish, and tries
    to queue a job for context A, but since the context is
    empty it won't do anything.

In this scenario, queued job B will never run. Fix this by calling
v4l2_m2m_try_run from v4l2_m2m_try_schedule.

While here, add more documentation to these functions.

Fixes: 34dbb848 ("media: mem2mem: Remove excessive try_run call")

Signed-off-by: default avatarEzequiel Garcia <ezequiel@collabora.com>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: split >80 cols line]
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent 39dd23dc

drivers/media/v4l2-core/v4l2-mem2mem.c

+30 −3
Original line number Diff line number Diff line
@@ -249,15 +249,24 @@ static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev) 
	m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;

	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);



	dprintk("Running job on m2m_ctx: %p\n", m2m_dev->curr_ctx);

	m2m_dev->m2m_ops->device_run(m2m_dev->curr_ctx->priv);

}



void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)

/*

 * __v4l2_m2m_try_queue() - queue a job

 * @m2m_dev: m2m device

 * @m2m_ctx: m2m context

 *

 * Check if this context is ready to queue a job.

 *

 * This function can run in interrupt context.

 */

static void __v4l2_m2m_try_queue(struct v4l2_m2m_dev *m2m_dev,

				 struct v4l2_m2m_ctx *m2m_ctx)

{

	struct v4l2_m2m_dev *m2m_dev;

	unsigned long flags_job, flags_out, flags_cap;



	m2m_dev = m2m_ctx->m2m_dev;

	dprintk("Trying to schedule a job for m2m_ctx: %p\n", m2m_ctx);



	if (!m2m_ctx->out_q_ctx.q.streaming
@@ -315,7 +324,25 @@ void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx) 
	m2m_ctx->job_flags |= TRANS_QUEUED;



	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);

}



/**

 * v4l2_m2m_try_schedule() - schedule and possibly run a job for any context

 * @m2m_ctx: m2m context

 *

 * 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.

 *

 * Note that v4l2_m2m_try_schedule() can schedule one job for this context,

 * and then run another job for another context.

 */

void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)

{

	struct v4l2_m2m_dev *m2m_dev = m2m_ctx->m2m_dev;



	__v4l2_m2m_try_queue(m2m_dev, m2m_ctx);

	v4l2_m2m_try_run(m2m_dev);

}

EXPORT_SYMBOL_GPL(v4l2_m2m_try_schedule);

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