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[2a00:1028:c000:ddf:8c68:4a09:6ad6:6324]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fde180a39sm34612165e9.1.2026.09.22.17.14.39 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 22 Sep 2026 17:14:40 -0700 (PDT) From: Josef Schlehofer To: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Hyunwoo Kim , Josef Schlehofer , stable@vger.kernel.org Subject: [PATCH 5/6] media: dvb-core: dmxdev: wake up readers on release Date: Wed, 23 Sep 2026 02:14:09 +0200 Message-ID: <20260923001410.30297-6-pepe.schlehofer@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260923001410.30297-1-pepe.schlehofer@gmail.com> References: <20260923001410.30297-1-pepe.schlehofer@gmail.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit dvb_dmxdev_release() sets dmxdev->exit and waits for open demux and DVR files to close, but readers blocked in dvb_dmxdev_buffer_read() wait only for data or buffer->error. Setting exit therefore does not wake a blocked read or epoll wait. The release, for example on a USB disconnect, then waits forever. Set -ENODEV on the DVR buffer and open filter buffers, wake their wait queues, and return -ENODEV from dvb_demux_read() once exit is set. Do not flush buffers when consuming -ENODEV so all readers see the error. Blocking DMX_DQBUF waiters are not covered. Fixes: 57861b432bda ("V4L/DVB (5511): Fix 2/3 for bug 7819: demux and dvr") Cc: stable@vger.kernel.org Signed-off-by: Josef Schlehofer --- drivers/media/dvb-core/dmxdev.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/drivers/media/dvb-core/dmxdev.c b/drivers/media/dvb-core/dmxdev.c index 6a825d9bae43..5f872bc89345 100644 --- a/drivers/media/dvb-core/dmxdev.c +++ b/drivers/media/dvb-core/dmxdev.c @@ -63,7 +63,9 @@ static ssize_t dvb_dmxdev_buffer_read(struct dvb_ringbuffer *src, if (src->error) { ret = src->error; - dvb_ringbuffer_flush(src); + /* -ENODEV: the demux is gone for good, keep it for all readers */ + if (ret != -ENODEV) + dvb_ringbuffer_flush(src); return ret; } @@ -81,7 +83,8 @@ static ssize_t dvb_dmxdev_buffer_read(struct dvb_ringbuffer *src, if (src->error) { ret = src->error; - dvb_ringbuffer_flush(src); + if (ret != -ENODEV) + dvb_ringbuffer_flush(src); break; } @@ -1035,6 +1038,9 @@ dvb_demux_read(struct file *file, char __user *buf, size_t count, struct dmxdev_filter *dmxdevfilter = file->private_data; int ret; + if (dmxdevfilter->dev->exit) + return -ENODEV; + if (mutex_lock_interruptible(&dmxdevfilter->mutex)) return -ERESTARTSYS; @@ -1457,8 +1463,29 @@ EXPORT_SYMBOL(dvb_dmxdev_init); void dvb_dmxdev_release(struct dmxdev *dmxdev) { + int i; + mutex_lock(&dmxdev->mutex); dmxdev->exit = 1; + + /* + * Wake up everyone blocked in read() or poll() on the demux and dvr + * devices, so that they see the error, close their file handles and + * let the waits below finish. + */ + spin_lock_irq(&dmxdev->lock); + dmxdev->dvr_buffer.error = -ENODEV; + for (i = 0; i < dmxdev->filternum; i++) { + if (dmxdev->filter[i].state >= DMXDEV_STATE_ALLOCATED) + dmxdev->filter[i].buffer.error = -ENODEV; + } + spin_unlock_irq(&dmxdev->lock); + + wake_up_all(&dmxdev->dvr_buffer.queue); + for (i = 0; i < dmxdev->filternum; i++) { + if (dmxdev->filter[i].state >= DMXDEV_STATE_ALLOCATED) + wake_up_all(&dmxdev->filter[i].buffer.queue); + } mutex_unlock(&dmxdev->mutex); if (dmxdev->dvbdev->users > 1) { -- 2.54.0 (Apple Git-157)