From 9db3bbf58be59ab496ccd1c7528f4b0e8835c5b1 Mon Sep 17 00:00:00 2001 From: Ezequiel Garcia Date: Wed, 25 Jul 2018 13:15:12 -0400 Subject: [PATCH] media: v4l2-mem2mem: Fix missing v4l2_m2m_try_run call Commit 34dbb848d5e4 ("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: 34dbb848d5e4 ("media: mem2mem: Remove excessive try_run call") Signed-off-by: Ezequiel Garcia Signed-off-by: Hans Verkuil [hans.verkuil@cisco.com: split >80 cols line] Signed-off-by: Mauro Carvalho Chehab --- drivers/media/v4l2-core/v4l2-mem2mem.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c index d9565ee..0a93c5b 100644 --- a/drivers/media/v4l2-core/v4l2-mem2mem.c +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c @@ -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); -- 2.7.4