On Mon May 11 20:12:07 2026 +0300, Valery Borovsky wrote:
> The vb2 framework hands buffers to the driver via buf_queue() before
> calling start_streaming(). If start_streaming() returns an error
> without first returning those buffers via vb2_buffer_done(),
> vb2_start_streaming() fires WARN_ON(owned_by_drv_count) and the queued
> buffers leak.
>
> msi2500_start_streaming() had five error paths that all hit this trap
> and were further tangled by ret-overwriting between calls:
>
> - -ENODEV when the USB device was already disconnected
> - -ERESTARTSYS when mutex_lock_interruptible() was interrupted
> - msi2500_set_usb_adc() failure: ret was silently overwritten by
> the next call (msi2500_isoc_init), so the error was lost entirely
> - msi2500_isoc_init() failure: cleanup_queued_bufs was called, but
> the function then fell through to msi2500_ctrl_msg() and again
> masked the original error by overwriting ret
> - msi2500_ctrl_msg(CMD_START_STREAMING) failure: no cleanup at all,
> leaving isoc URBs submitted with no way for the driver to consume
> them
>
> Consolidate the error paths into a small goto chain. Every failure
> now stops the function, drains the queued-buffer list, and returns
> the real error code. The ctrl_msg failure path also rolls back the
> preceding msi2500_isoc_init() via msi2500_isoc_cleanup() before
> unlocking and draining.
>
> The cleanup helper takes a vb2_buffer_state argument so that the
> start_streaming error paths can pass VB2_BUF_STATE_QUEUED (as
> expected by userspace on start_streaming failure) while stop_streaming
> keeps its existing VB2_BUF_STATE_ERROR semantics.
>
> This mirrors the uvcvideo fix in commit 4cf3b6fd54eb ("media: uvcvideo:
> Return queued buffers on start_streaming() failure").
>
> Fixes: 977e444f59ad ("[media] Mirics MSi3101 SDR Dongle driver")
> Cc: [email protected]
> Signed-off-by: Valery Borovsky <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/usb/msi2500/msi2500.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)
---
diff --git a/drivers/media/usb/msi2500/msi2500.c
b/drivers/media/usb/msi2500/msi2500.c
index 1ff98956b680..0614087c3c3c 100644
--- a/drivers/media/usb/msi2500/msi2500.c
+++ b/drivers/media/usb/msi2500/msi2500.c
@@ -541,7 +541,8 @@ static int msi2500_isoc_init(struct msi2500_dev *dev)
}
/* Must be called with vb_queue_lock hold */
-static void msi2500_cleanup_queued_bufs(struct msi2500_dev *dev)
+static void msi2500_cleanup_queued_bufs(struct msi2500_dev *dev,
+ enum vb2_buffer_state state)
{
unsigned long flags;
@@ -554,7 +555,7 @@ static void msi2500_cleanup_queued_bufs(struct msi2500_dev
*dev)
buf = list_entry(dev->queued_bufs.next,
struct msi2500_frame_buf, list);
list_del(&buf->list);
- vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
+ vb2_buffer_done(&buf->vb.vb2_buf, state);
}
spin_unlock_irqrestore(&dev->queued_bufs_lock, flags);
}
@@ -830,25 +831,40 @@ static int msi2500_start_streaming(struct vb2_queue *vq,
unsigned int count)
dev_dbg(dev->dev, "\n");
- if (!dev->udev)
- return -ENODEV;
+ if (!dev->udev) {
+ ret = -ENODEV;
+ goto err_cleanup;
+ }
- if (mutex_lock_interruptible(&dev->v4l2_lock))
- return -ERESTARTSYS;
+ if (mutex_lock_interruptible(&dev->v4l2_lock)) {
+ ret = -ERESTARTSYS;
+ goto err_cleanup;
+ }
/* wake-up tuner */
v4l2_subdev_call(dev->v4l2_subdev, core, s_power, 1);
ret = msi2500_set_usb_adc(dev);
+ if (ret)
+ goto err_unlock_cleanup;
ret = msi2500_isoc_init(dev);
if (ret)
- msi2500_cleanup_queued_bufs(dev);
+ goto err_unlock_cleanup;
ret = msi2500_ctrl_msg(dev, CMD_START_STREAMING, 0);
+ if (ret)
+ goto err_isoc_cleanup;
mutex_unlock(&dev->v4l2_lock);
+ return 0;
+err_isoc_cleanup:
+ msi2500_isoc_cleanup(dev);
+err_unlock_cleanup:
+ mutex_unlock(&dev->v4l2_lock);
+err_cleanup:
+ msi2500_cleanup_queued_bufs(dev, VB2_BUF_STATE_QUEUED);
return ret;
}
@@ -863,7 +879,7 @@ static void msi2500_stop_streaming(struct vb2_queue *vq)
if (dev->udev)
msi2500_isoc_cleanup(dev);
- msi2500_cleanup_queued_bufs(dev);
+ msi2500_cleanup_queued_bufs(dev, VB2_BUF_STATE_ERROR);
/* according to tests, at least 700us delay is required */
msleep(20);
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