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Date: Fri, 18 Jul 1997 11:56:00 +0400 (MSD)
From: =?KOI8-R?B?4c7E0sXKIP7F0s7P1w==?= <ache@nagual.pp.ru>
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To: Peter Wemm <peter@spinner.dialix.com.au>
cc: FreeBSD-current <current@freebsd.org>
Subject: Re: sleep.c fix for review 
In-Reply-To: <199707180733.PAA13192@spinner.dialix.com.au>
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On Fri, 18 Jul 1997, Peter Wemm wrote:

> As I read it, this doesn't actually change anything..  If the application
> has masked SIGALRM, unconditionally installing and removing the handler
> does nothing..  That's what the optimization does..  If SIGALRM is 
> impossible, don't waste syscalls on something that will not happen.

You are right, I overlook it, here is new variant:

*** sleep.c.orig	Fri Jun  6 00:30:02 1997
--- sleep.c	Fri Jul 18 11:49:37 1997
***************
*** 73,79 ****
  	struct timespec time_remaining;
  	struct sigaction act, oact;
  	sigset_t mask, omask;
- 	int alarm_blocked;
  
  	if (seconds != 0) {
  		time_to_sleep.tv_sec = seconds;
--- 73,78 ----
***************
*** 84,101 ****
  		sigaddset(&mask, SIGALRM);
  		sigprocmask(SIG_BLOCK, &mask, &omask);
  
! 		/* Was SIGALRM blocked already? */
! 		alarm_blocked = sigismember(&omask, SIGALRM);
! 
! 		if (!alarm_blocked) {
! 			/*
! 			 * Set up handler to interrupt signanosleep only if
! 			 * SIGALRM was unblocked. (Save some syscalls)
! 			 */
! 			memset(&act, 0, sizeof(act));
! 			act.sa_handler = sleephandler;
! 			sigaction(SIGALRM, &act, &oact);
! 		}
  
  		/*
  		 * signanosleep() uses the given mask for the lifetime of
--- 83,99 ----
  		sigaddset(&mask, SIGALRM);
  		sigprocmask(SIG_BLOCK, &mask, &omask);
  
! 		/*
! 		 * Set up handler to interrupt signanosleep only if
! 		 * SIGALRM was unblocked. (Save some syscalls)
! 		 */
! 		memset(&act, 0, sizeof(act));
! 		act.sa_handler = sleephandler;
! 		sigaction(SIGALRM, &act, &oact);
! 
! 		/* Always enable SIGALRM to be compatible */
! 		mask = omask;
! 		sigdelset(&mask, SIGALRM);
  
  		/*
  		 * signanosleep() uses the given mask for the lifetime of
***************
*** 105,117 ****
  		 * to end the timout.  If the process blocks SIGALRM, it
  		 * gets what it asks for.
  		 */
! 		signanosleep(&time_to_sleep, &time_remaining, &omask);
  
! 		if (!alarm_blocked) {
! 			/* Unwind */
! 			sigaction(SIGALRM, &oact, (struct sigaction *)0);
! 			sigprocmask(SIG_SETMASK, &omask, (sigset_t *)0);
! 		}
  
  		/* return how long is left */
  		seconds = time_remaining.tv_sec;
--- 103,113 ----
  		 * to end the timout.  If the process blocks SIGALRM, it
  		 * gets what it asks for.
  		 */
! 		signanosleep(&time_to_sleep, &time_remaining, &mask);
  
! 		/* Unwind */
! 		sigaction(SIGALRM, &oact, (struct sigaction *)0);
! 		sigprocmask(SIG_SETMASK, &omask, (sigset_t *)0);
  
  		/* return how long is left */
  		seconds = time_remaining.tv_sec;

-- 
Andrey A. Chernov
<ache@null.net>
http://www.nagual.pp.ru/~ache/