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    Subject[PATCH AUTOSEL 5.1 134/219] media: coda: fix last buffer handling in V4L2_ENC_CMD_STOP
    Date
    From: Marco Felsch <m.felsch@pengutronix.de>

    [ Upstream commit f3775f89852d167990b0d718587774cf00d22ac2 ]

    coda_encoder_cmd() is racy, as the last scheduled picture run worker can
    still be in-flight while the ENC_CMD_STOP command is issued. Depending
    on the exact timing the sequence numbers might already be changed, but
    the last buffer might not have been put on the destination queue yet.

    In this case the current implementation would prematurely wake the
    destination queue with last_buffer_dequeued=true, causing userspace to
    call streamoff before the last buffer is handled.

    Close this race window by synchronizing with the pic_run_worker before
    doing the sequence check.

    Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
    [l.stach@pengutronix.de: switch to flush_work, reword commit message]
    Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
    Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
    Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/media/platform/coda/coda-common.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/media/platform/coda/coda-common.c b/drivers/media/platform/coda/coda-common.c
    index fa0b22fb7991..9bf2116ffc76 100644
    --- a/drivers/media/platform/coda/coda-common.c
    +++ b/drivers/media/platform/coda/coda-common.c
    @@ -1007,6 +1007,8 @@ static int coda_encoder_cmd(struct file *file, void *fh,
    /* Set the stream-end flag on this context */
    ctx->bit_stream_param |= CODA_BIT_STREAM_END_FLAG;

    + flush_work(&ctx->pic_run_work);
    +
    /* If there is no buffer in flight, wake up */
    if (!ctx->streamon_out || ctx->qsequence == ctx->osequence) {
    dst_vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx,
    --
    2.20.1
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