Re: [PATCH 2/4] swait: add the missing killable swaits

Greg KH
2017-06-29T12:54:02Z

On Wed, Jun 14, 2017 at 03:20:15PM -0700, Luis R. Rodriguez wrote:
> Code in kernel which incorrectly used the non-killable variants could
> end up having waits killed improperly. The respective killable waits
> have been upstream for a while:
>
> o wait_for_completion_killable()
> o wait_for_completion_killable_timeout()
>
> swait has been upstream since v4.6. Older kernels have had the
> above variants in place for a long time.
>
> Cc: stable <stable@vger.kernel.org> # 4.6
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
> include/linux/swait.h | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/include/linux/swait.h b/include/linux/swait.h
> index c1f9c62a8a50..2c700694d50a 100644
> --- a/include/linux/swait.h
> +++ b/include/linux/swait.h
> @@ -169,4 +169,29 @@ do { \
> __ret; \
> })
>
> +#define __swait_event_killable(wq, condition) \
> + ___swait_event(wq, condition, TASK_KILLABLE, 0, schedule())
> +
> +#define swait_event_killable(wq, condition) \
> +({ \
> + int __ret = 0; \
> + if (!(condition)) \
> + __ret = __swait_event_killable(wq, condition); \
> + __ret; \
> +})
> +
> +#define __swait_event_killable_timeout(wq, condition, timeout) \
> + ___swait_event(wq, ___wait_cond_timeout(condition), \
> + TASK_KILLABLE, timeout, \
> + __ret = schedule_timeout(__ret))
> +
> +#define swait_event_killable_timeout(wq, condition, timeout) \
> +({ \
> + long __ret = timeout; \
> + if (!___wait_cond_timeout(condition)) \
> + __ret = __swait_event_killable_timeout(wq, \
> + condition, timeout); \
> + __ret; \
> +})
> +
> #endif /* _LINUX_SWAIT_H */

Do you really still want to add these, now that we know we shouldn't be
using swait in "real" code? :)

thanks,

greg k-h