4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 69ef9bc54715fb1cb7786ada15774e469e822209 ]
On module unload/remove, we need to ensure that work does not run after we have freed resources. Concretely, cancel_delayed_work() may return while the callback function is still running.
From kernel/workqueue.c:
The work callback function may still be running on return, unless it returns true and the work doesn't re-arm itself. Explicitly flush or use cancel_delayed_work_sync() to wait on it.
Link: https://lore.kernel.org/lkml/20190204220952.30761-1-TheSven73@googlemail.com... Reported-by: Sven Van Asbroeck thesven73@gmail.com Reviewed-by: Dmitry Torokhov dmitry.torokhov@gmail.com Reviewed-by: Sven Van Asbroeck TheSven73@gmail.com Acked-by: Robin van der Gracht robin@protonic.nl Signed-off-by: Miguel Ojeda miguel.ojeda.sandonis@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/auxdisplay/ht16k33.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c index a43276c76fc6..21393ec3b9a4 100644 --- a/drivers/auxdisplay/ht16k33.c +++ b/drivers/auxdisplay/ht16k33.c @@ -509,7 +509,7 @@ static int ht16k33_remove(struct i2c_client *client) struct ht16k33_priv *priv = i2c_get_clientdata(client); struct ht16k33_fbdev *fbdev = &priv->fbdev;
- cancel_delayed_work(&fbdev->work); + cancel_delayed_work_sync(&fbdev->work); unregister_framebuffer(fbdev->info); framebuffer_release(fbdev->info); free_page((unsigned long) fbdev->buffer);