lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 25 Aug 2020 23:55:55 +0900 From: Alexandre Courbot <gnurou@...il.com> To: Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil <hverkuil-cisco@...all.nl>, Nicolas Dufresne <nicolas.dufresne@...labora.com> Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, Alexandre Courbot <gnurou@...il.com> Subject: [PATCH 1/2] media: v4l2-mem2mem: consider OUTPUT queue first when polling If poll() is called on a m2m device with the EPOLLOUT event after the last buffer of the CAPTURE queue is dequeued, any buffer available on OUTPUT queue will never be signaled because v4l2_m2m_poll_for_data() starts by checking whether dst_q->last_buffer_dequeued is set and returns EPOLLIN in this case, without looking at the state of the OUTPUT queue. Fix this by checking the state of the OUTPUT queue before considering that early-return case. This also has the side-effect of bringing the two blocks of code dealing with the CAPTURE queue next to one another, and saves us one spin lock/unlock cycle, for what it's worth. Signed-off-by: Alexandre Courbot <gnurou@...il.com> --- drivers/media/v4l2-core/v4l2-mem2mem.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c index 95a8f2dc5341d..0d0192119af20 100644 --- a/drivers/media/v4l2-core/v4l2-mem2mem.c +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c @@ -862,6 +862,15 @@ static __poll_t v4l2_m2m_poll_for_data(struct file *file, list_empty(&dst_q->queued_list))) return EPOLLERR; + spin_lock_irqsave(&src_q->done_lock, flags); + if (!list_empty(&src_q->done_list)) + src_vb = list_first_entry(&src_q->done_list, struct vb2_buffer, + done_entry); + if (src_vb && (src_vb->state == VB2_BUF_STATE_DONE + || src_vb->state == VB2_BUF_STATE_ERROR)) + rc |= EPOLLOUT | EPOLLWRNORM; + spin_unlock_irqrestore(&src_q->done_lock, flags); + spin_lock_irqsave(&dst_q->done_lock, flags); if (list_empty(&dst_q->done_list)) { /* @@ -870,21 +879,11 @@ static __poll_t v4l2_m2m_poll_for_data(struct file *file, */ if (dst_q->last_buffer_dequeued) { spin_unlock_irqrestore(&dst_q->done_lock, flags); - return EPOLLIN | EPOLLRDNORM; + rc |= EPOLLIN | EPOLLRDNORM; + return rc; } } - spin_unlock_irqrestore(&dst_q->done_lock, flags); - spin_lock_irqsave(&src_q->done_lock, flags); - if (!list_empty(&src_q->done_list)) - src_vb = list_first_entry(&src_q->done_list, struct vb2_buffer, - done_entry); - if (src_vb && (src_vb->state == VB2_BUF_STATE_DONE - || src_vb->state == VB2_BUF_STATE_ERROR)) - rc |= EPOLLOUT | EPOLLWRNORM; - spin_unlock_irqrestore(&src_q->done_lock, flags); - - spin_lock_irqsave(&dst_q->done_lock, flags); if (!list_empty(&dst_q->done_list)) dst_vb = list_first_entry(&dst_q->done_list, struct vb2_buffer, done_entry); -- 2.28.0
Powered by blists - more mailing lists