[PATCH] drm/dp: Allow signals to interrupt drm_aux-dev reads/writes

[Jani Nikula]

On Wed, 27 Apr 2016, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Let's be nice and interrupt the dpcd aux-dev reads/writes when there's
> a signal pending. Much nicer if the user can hit ^C instead of having to
> sit around waiting for the read/write to finish.
>
> time dd if=/dev/drm_dp_aux0 bs=$((1024*1024))
> ^C
>
> before:
>  real	0m34.681s
>  user	0m0.003s
>  sys	0m6.880s
>
> after:
>  real	0m0.222s
>  user	0m0.006s
>  sys	0m0.057s
>
> Cc: Rafael Antognolli <rafael.antognolli at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula at intel.com>


> ---
>  drivers/gpu/drm/drm_dp_aux_dev.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
> index f73b38b33a8e..3334baacf43d 100644
> --- a/drivers/gpu/drm/drm_dp_aux_dev.c
> +++ b/drivers/gpu/drm/drm_dp_aux_dev.c
> @@ -159,6 +159,12 @@ static ssize_t auxdev_read(struct file *file, char __user *buf, size_t count,
>  		uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
>  		ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
>  
> +		if (signal_pending(current)) {
> +			res = num_bytes_processed ?
> +				num_bytes_processed : -ERESTARTSYS;
> +			goto out;
> +		}
> +
>  		res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo);
>  		if (res <= 0) {
>  			res = num_bytes_processed ? num_bytes_processed : res;
> @@ -202,6 +208,12 @@ static ssize_t auxdev_write(struct file *file, const char __user *buf,
>  		uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
>  		ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
>  
> +		if (signal_pending(current)) {
> +			res = num_bytes_processed ?
> +				num_bytes_processed : -ERESTARTSYS;
> +			goto out;
> +		}
> +
>  		if (__copy_from_user(localbuf,
>  				     buf + num_bytes_processed, todo)) {
>  			res = num_bytes_processed ?

-- 
Jani Nikula, Intel Open Source Technology Center