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Fix a race that can stall the timer when we remove a timer that has another

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timer with a <0.05 second delta next to it.

This is done by avoiding the possibility of updating the first residual
time delta in the timer list to zero.

PR:		102747
Submitted by:	Sergey Zaharchenko - doublef-ctm at yandex dot ru
MFC after:	3 weeks
This commit is contained in:
Brian Somers 2009-05-26 07:32:08 +00:00
parent bf7d2c1797
commit 096d622d17
1 changed files with 23 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
usr.sbin/ppp/timer.c
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@ -1,5 +1,5 @@
/*-
* Copyright (c) 1996 - 2001 Brian Somers <brian@Awfulhak.org>
* Copyright (c) 1996 - 2001, 2009 Brian Somers <brian@Awfulhak.org>
* based on work by Toshiharu OHNO <tony-o@iij.ad.jp>
* Internet Initiative Japan, Inc (IIJ)
* All rights reserved.
@ -94,9 +94,12 @@ timer_Start(struct pppTimer *tp)
return;
}
/* Adjust our first delta so that it reflects what's really happening */
/*
* We just need to insert tp in the correct relative place. We don't
* need to adjust TimerList->rest (yet).
*/
if (TimerList && getitimer(ITIMER_REAL, &itimer) == 0)
TimerList->rest = RESTVAL(itimer);
ticks = RESTVAL(itimer) - TimerList->rest;
pt = NULL;
for (t = TimerList; t; t = t->next) {
@ -132,6 +135,7 @@ timer_Start(struct pppTimer *tp)
static void
StopTimerNoBlock(struct pppTimer *tp)
{
struct itimerval itimer;
struct pppTimer *t, *pt;
/*
@ -156,14 +160,11 @@ StopTimerNoBlock(struct pppTimer *tp)
timer_TermService(); /* Terminate Timer Service */
}
if (t->next) {
if (!pt) { /* t (tp) was the first in the list */
struct itimerval itimer;
if (getitimer(ITIMER_REAL, &itimer) == 0)
t->rest = RESTVAL(itimer);
}
t->next->rest += t->rest;
if (!pt) /* t->next is now the first in the list */
if (!pt && getitimer(ITIMER_REAL, &itimer) == 0)
t->next->rest += RESTVAL(itimer); /* t (tp) was the first in the list */
else
t->next->rest += t->rest;
if (!pt && t->next->rest > 0) /* t->next is now the first in the list */
timer_InitService(1);
}
} else {
@ -235,11 +236,19 @@ timer_Show(int LogLevel, struct prompt *prompt)
{
struct itimerval itimer;
struct pppTimer *pt;
u_long rest = 0;
long rest;
/* Adjust our first delta so that it reflects what's really happening */
/*
* Adjust the base time so that the deltas reflect what's really
* happening. Changing TimerList->rest might cause it to become zero
* (if getitimer() returns a value close to zero), and the
* timer_InitService() call will call setitimer() with zero it_value,
* stopping the itimer... so be careful!
*/
if (TimerList && getitimer(ITIMER_REAL, &itimer) == 0)
TimerList->rest = RESTVAL(itimer);
rest = RESTVAL(itimer) - TimerList->rest;
else
rest = 0;
#define SECS(val) ((val) / SECTICKS)
#define HSECS(val) (((val) % SECTICKS) * 100 / SECTICKS)