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fix a bug reported by Steven M. Bellovin regarding oversleeping 

select(2) timeouts. Introduced via timecounter branch from a
tvtohz() conversion.
The left over timeout was not decremented when re-starting
the sleep in select.
This commit is contained in:
kardel 2006-07-08 12:16:09 +00:00
parent d788cc37f6
commit e472b9091e
1 changed files with 21 additions and 5 deletions
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26
sys/kern/sys_generic.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: sys_generic.c,v 1.86 2006/06/07 22:33:40 kardel Exp $ */
/* $NetBSD: sys_generic.c,v 1.87 2006/07/08 12:16:09 kardel Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_generic.c,v 1.86 2006/06/07 22:33:40 kardel Exp $");
__KERNEL_RCSID(0, "$NetBSD: sys_generic.c,v 1.87 2006/07/08 12:16:09 kardel Exp $");
#include "opt_ktrace.h"
@ -753,6 +753,7 @@ selcommon(struct lwp *l, register_t *retval, int nd, fd_set *u_in,
int s, ncoll, error, timo;
size_t ni;
sigset_t oldmask;
struct timeval sleepts;
error = 0;
if (nd < 0)
@ -780,9 +781,14 @@ selcommon(struct lwp *l, register_t *retval, int nd, fd_set *u_in,
#undef getbits
timo = 0;
if (tv && itimerfix(tv)) {
error = EINVAL;
goto done;
timerclear(&sleepts);
if (tv) {
if (itimerfix(tv)) {
error = EINVAL;
goto done;
}
getmicrouptime(&sleepts);
}
if (mask)
(void)sigprocmask1(p, SIG_SETMASK, mask, &oldmask);
@ -798,6 +804,16 @@ selcommon(struct lwp *l, register_t *retval, int nd, fd_set *u_in,
/*
* We have to recalculate the timeout on every retry.
*/
struct timeval slepttime;
/*
* reduce tv by elapsed time
* based on monotonic time scale
*/
getmicrouptime(&slepttime);
timeradd(tv, &slepttime, tv);
timersub(tv, &sleepts, tv);
sleepts = slepttime;
timo = tvtohz(tv);
if (timo <= 0)
goto done;