Re: [PATCH 4/4] select: make select() and poll() waits freezable

[Jan Kara]

On Wed 27-05-26 14:49:12, Dai Junbing wrote:
> Tasks blocked in select() or poll() may be woken during suspend and
> resume due to freezer state transitions. This can cause avoidable
> activity in the suspend/resume path and add unnecessary overhead.
> 
> Mark the waits in do_select() and do_poll() as freezable so these tasks
> are not unnecessarily woken by the freezer.
> 
> Both functions are only used from their respective system call paths,
> where the task sleeps without holding locks that would make freezing
> unsafe.
> 
> Signed-off-by: Dai Junbing <daijunbing@xxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/select.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/select.c b/fs/select.c
> index bf71c9838dfe..b0b279748355 100644
> --- a/fs/select.c
> +++ b/fs/select.c
> @@ -600,7 +600,7 @@ static noinline_for_stack int do_select(int n, fd_set_bits *fds, struct timespec
>  			to = &expire;
>  		}
>  
> -		if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
> +		if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE|TASK_FREEZABLE,
>  					   to, slack))
>  			timed_out = 1;
>  	}
> @@ -962,7 +962,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
>  			to = &expire;
>  		}
>  
> -		if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
> +		if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE|TASK_FREEZABLE, to, slack))
>  			timed_out = 1;
>  	}
>  	return count;
> -- 
> 2.25.1
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR