[systemd-devel] [PATCH] udev: settle should return immediately when timeout is 0

[Andrei Borzenkov]

В Sat, 11 Apr 2015 23:31:05 +0300
Nir Soffer <nirsof at gmail.com> пишет:

> udevadm manual says:
> 
>     A value of 0 will check if the queue is empty and always return
>     immediately.
> 
> However, currently we ignore the deadline if the value is 0, and wait
> without any limit.
> 
> Zero timeout behaved according to the documentation until commit
> ead7c62ab7 (udevadm: settle - kill alarm()). Looking at this patch, it
> seems that the behavior change was unintended.
> 
> This patch restores the documented behavior.
> ---
>  src/udev/udevadm-settle.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/src/udev/udevadm-settle.c b/src/udev/udevadm-settle.c
> index 2c84ada..0c9c1d9 100644
> --- a/src/udev/udevadm-settle.c
> +++ b/src/udev/udevadm-settle.c
> @@ -49,7 +49,7 @@ static int adm_settle(struct udev *udev, int argc, char *argv[]) {
>                  { "quiet",          no_argument,       NULL, 'q' }, /* removed */
>                  {}
>          };
> -        usec_t deadline;
> +        usec_t deadline = 0;

This is redundant.

>          const char *exists = NULL;
>          unsigned int timeout = 120;
>          struct pollfd pfd[1] = { {.fd = -1}, };
> @@ -99,7 +99,8 @@ static int adm_settle(struct udev *udev, int argc, char *argv[]) {
>                  return EXIT_FAILURE;
>          }
>  
> -        deadline = now(CLOCK_MONOTONIC) + timeout * USEC_PER_SEC;
> +        if (timeout != 0)
> +                deadline = now(CLOCK_MONOTONIC) + timeout * USEC_PER_SEC;
>  

And this.

>          /* guarantee that the udev daemon isn't pre-processing */
>          if (getuid() == 0) {
> @@ -142,7 +143,7 @@ static int adm_settle(struct udev *udev, int argc, char *argv[]) {
>                          break;
>                  }
>  
> -                if (timeout > 0 && now(CLOCK_MONOTONIC) >= deadline)
> +                if (timeout == 0 || now(CLOCK_MONOTONIC) >= deadline)


Just remove "timeout > 0 && " condition. This will cause loop to always
exit after first iteration.

>                          break;
>  
>                  /* wake up when queue is empty */