Hi,
On 5/13/21 3:44 PM, Maximilian Luz wrote:
> The poll function should not return -ERESTARTSYS.
>
> Furthermore, locking in this function is completely unnecessary. The
> ddev->lock protects access to the main device and controller (ddev->dev
> and ddev->ctrl), ensuring that both are and remain valid while being
> accessed by clients. Both are, however, never accessed in the poll
> function. The shutdown test (via atomic bit flags) be safely done
> without locking, so drop locking here entirely.
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Fixes: 1d609992832e ("platform/surface: Add DTX driver> Signed-off-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>
Thank you for your patch, I've applied this patch to my review-hans
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans
I will also include this in the next pdx86-fixes pull-req for 5.13.
Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.
Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.
Regards,
Hans
> ---
> drivers/platform/surface/surface_dtx.c | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/drivers/platform/surface/surface_dtx.c b/drivers/platform/surface/surface_dtx.c
> index 63ce587e79e3..5d9b758a99bb 100644
> --- a/drivers/platform/surface/surface_dtx.c
> +++ b/drivers/platform/surface/surface_dtx.c
> @@ -527,20 +527,14 @@ static __poll_t surface_dtx_poll(struct file *file, struct poll_table_struct *pt
> struct sdtx_client *client = file->private_data;
> __poll_t events = 0;
>
> - if (down_read_killable(&client->ddev->lock))
> - return -ERESTARTSYS;
> -
> - if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags)) {
> - up_read(&client->ddev->lock);
> + if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags))
> return EPOLLHUP | EPOLLERR;
> - }
>
> poll_wait(file, &client->ddev->waitq, pt);
>
> if (!kfifo_is_empty(&client->buffer))
> events |= EPOLLIN | EPOLLRDNORM;
>
> - up_read(&client->ddev->lock);
> return events;
> }
>
>
