Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Actually, we cannot release the megalock before we take sleepermtx, 

since that opens a race window for non-mpsafe code, so do it after.
Additionally, we cannot call mutex_enter() for sleepermtx, since
ltsleep/mtsleep should not block (i.e. release kernel lock) before
actually blocking, so busyloop in mutex_tryenter().  Finally, when
waking up, take kernel lock back only *after* releasing sleepermtx
to avoid deadlock against another thread holding the kernel lock
and wanting sleepermtx.
This commit is contained in:
pooka 2009-09-04 16:41:39 +00:00
parent 4aff350284
commit 77c3d9700d
1 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
sys/rump/librump/rumpkern/ltsleep.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: ltsleep.c,v 1.15 2009/09/04 13:58:57 pooka Exp $ */
/* $NetBSD: ltsleep.c,v 1.16 2009/09/04 16:41:39 pooka Exp $ */
/*
* Copyright (c) 2007 Antti Kantee. All Rights Reserved.
@ -29,7 +29,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ltsleep.c,v 1.15 2009/09/04 13:58:57 pooka Exp $");
__KERNEL_RCSID(0, "$NetBSD: ltsleep.c,v 1.16 2009/09/04 16:41:39 pooka Exp $");
#include <sys/param.h>
#include <sys/proc.h>
@ -58,12 +58,12 @@ ltsleep(wchan_t ident, pri_t prio, const char *wmesg, int timo,
struct ltsleeper lts;
int nlocks;
KERNEL_UNLOCK_ALL(curlwp, &nlocks);
lts.id = ident;
cv_init(&lts.cv, NULL);
mutex_enter(&sleepermtx);
while (!mutex_tryenter(&sleepermtx))
continue;
KERNEL_UNLOCK_ALL(curlwp, &nlocks);
if (slock)
simple_unlock(slock);
LIST_INSERT_HEAD(&sleepers, &lts, entries);
@ -76,10 +76,11 @@ ltsleep(wchan_t ident, pri_t prio, const char *wmesg, int timo,
cv_destroy(&lts.cv);
KERNEL_LOCK(nlocks, curlwp);
if (slock && (prio & PNORELOCK) == 0)
simple_lock(slock);
KERNEL_LOCK(nlocks, curlwp);
return 0;
}
@ -90,12 +91,12 @@ mtsleep(wchan_t ident, pri_t prio, const char *wmesg, int timo,
struct ltsleeper lts;
int nlocks;
KERNEL_UNLOCK_ALL(curlwp, &nlocks);
lts.id = ident;
cv_init(&lts.cv, NULL);
mutex_enter(&sleepermtx);
while (!mutex_tryenter(&sleepermtx))
continue;
KERNEL_UNLOCK_ALL(curlwp, &nlocks);
LIST_INSERT_HEAD(&sleepers, &lts, entries);
/* protected by sleepermtx */
@ -107,10 +108,11 @@ mtsleep(wchan_t ident, pri_t prio, const char *wmesg, int timo,
cv_destroy(&lts.cv);
KERNEL_LOCK(nlocks, curlwp);
if ((prio & PNORELOCK) == 0)
mutex_enter(lock);
KERNEL_LOCK(nlocks, curlwp);
return 0;
}