Re: [PATCH take2] Use ERESTART_RESTARTBLOCK if poll() is interrupted by a signal

[Oleg Nesterov <oleg@tv-sign.ru>]

On 08/15, Chris Wright wrote:
>
>  fs/select.c |   31 ++++++++++++++++++++++++++++++-
>  1 files changed, 30 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/select.c b/fs/select.c
> index a974082..5562195 100644
> --- a/fs/select.c
> +++ b/fs/select.c
> @@ -736,10 +736,28 @@ out_fds:
>  	return err;
>  }
>  
> +long do_restart_poll(struct restart_block *restart_block)
> +{
> +	struct pollfd __user *ufds = (struct pollfd __user*)restart_block->arg0;
> +	int nfds = restart_block->arg1;
> +	s64 timeout = ((s64)restart_block->arg3<<32) | (s64)restart_block->arg2;
> +	int ret;
> +
> +	ret = do_sys_poll(ufds, nfds, &timeout);
> +	if (ret == -EINTR) {
> +		restart_block->fn = do_restart_poll;
> +		restart_block->arg2 = timeout & 0xFFFFFFFF;
> +		restart_block->arg3 = (u64)timeout >> 32;
> +		ret = -ERESTART_RESTARTBLOCK;
> +	}
> +	return ret;
> +}
> +
>  asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
>  			long timeout_msecs)
>  {
>  	s64 timeout_jiffies;
> +	int ret;
>  
>  	if (timeout_msecs > 0) {
>  #if HZ > 1000
> @@ -754,7 +772,18 @@ asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
>  		timeout_jiffies = timeout_msecs;
>  	}
>  
> -	return do_sys_poll(ufds, nfds, &timeout_jiffies);
> +	ret = do_sys_poll(ufds, nfds, &timeout_jiffies);
> +	if (ret == -EINTR) {
> +		struct restart_block *restart_block;
> +		restart_block = &current_thread_info()->restart_block;
> +		restart_block->fn = do_restart_poll;
> +		restart_block->arg0 = (unsigned long)ufds;
> +		restart_block->arg1 = nfds;
> +		restart_block->arg2 = timeout_jiffies & 0xFFFFFFFF;
> +		restart_block->arg3 = (u64)timeout_jiffies >> 32;
> +		ret = -ERESTART_RESTARTBLOCK;
> +	}
> +	return ret;
>  }
>  
>  #ifdef TIF_RESTORE_SIGMASK

Great, I think the patch is correct.

Oleg.