Date: Tue, 01 May 2007 13:34:52 +0200 From: des@des.no (Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?=) To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-current@freebsd.org, Stefan Ehmann <shoesoft@gmx.net> Subject: Re: strace causes panic: sleeping thread Message-ID: <864pmwbwv7.fsf@dwp.des.no> In-Reply-To: <20070501111902.GA2441@deviant.kiev.zoral.com.ua> (Kostik Belousov's message of "Tue, 1 May 2007 14:19:02 %2B0300") References: <200704281128.44077.shoesoft@gmx.net> <20070428115503.GM2441@deviant.kiev.zoral.com.ua> <86y7k8rgc4.fsf@dwp.des.no> <86tzuwrfui.fsf@dwp.des.no> <20070501111902.GA2441@deviant.kiev.zoral.com.ua>
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Kostik Belousov <kostikbel@gmail.com> writes:
> The procfs PIOCWAIT/PIOCWAIT32 ioctls drop the p_mtx for
> sleep. Could it be that p being freed/reused meantime ?
So it should be held while the lock is dropped. It is still a procfs
issue (and one that was present, although benign, before I removed
Giant from pseudofs). Please try this updated patch.
DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no
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Content-Type: text/x-patch
Content-Disposition: attachment; filename=procfs.diff
Index: sys/fs/procfs/procfs_ioctl.c
===================================================================
RCS file: /home/ncvs/src/sys/fs/procfs/procfs_ioctl.c,v
retrieving revision 1.16
diff -u -r1.16 procfs_ioctl.c
--- sys/fs/procfs/procfs_ioctl.c 19 Feb 2007 13:04:25 -0000 1.16
+++ sys/fs/procfs/procfs_ioctl.c 1 May 2007 11:30:22 -0000
@@ -70,7 +70,10 @@
int ival;
#endif
- PROC_LOCK(p);
+ KASSERT(p != NULL,
+ ("%s() called without a process", __func__));
+ PROC_LOCK_ASSERT(p, MA_OWNED);
+
error = 0;
switch (cmd) {
#if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
@@ -124,8 +127,10 @@
case PIOCWAIT:
while (p->p_step == 0 && (p->p_flag & P_WEXIT) == 0) {
/* sleep until p stops */
+ _PHOLD(p);
error = msleep(&p->p_stype, &p->p_mtx,
PWAIT|PCATCH, "pioctl", 0);
+ _PRELE(p);
if (error != 0)
break;
}
@@ -142,8 +147,10 @@
case PIOCWAIT32:
while (p->p_step == 0 && (p->p_flag & P_WEXIT) == 0) {
/* sleep until p stops */
+ _PHOLD(p);
error = msleep(&p->p_stype, &p->p_mtx,
PWAIT|PCATCH, "pioctl", 0);
+ _PRELE(p);
if (error != 0)
break;
}
@@ -193,7 +200,6 @@
default:
error = (ENOTTY);
}
- PROC_UNLOCK(p);
return (error);
}
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