d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Reduce the scope of the proctree_lock. If several processes cause

Browse Source 
continuous calls to the uprintf(9), the proctree_lock could be
shared-locked for indefinite amount of time, starving exclusive
requests. Since proctree_lock is needed for fork() and exit(), this
effectively stops the machine.

While there, do the similar reduction for tprintf(9).

Reported and tested by: pho
Reviewed by:    ed
Sponsored by:   The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (glebius)
This commit is contained in:
Konstantin Belousov 2013-09-13 06:39:10 +00:00
parent b11797ad2f
commit 8740a7112e
1 changed files with 6 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
sys/kern/subr_prf.c
View File

@ -151,26 +151,25 @@ uprintf(const char *fmt, ...)
PROC_LOCK(p);
if ((p->p_flag & P_CONTROLT) == 0) {
PROC_UNLOCK(p);
retval = 0;
goto out;
sx_sunlock(&proctree_lock);
return (0);
}
SESS_LOCK(p->p_session);
pca.tty = p->p_session->s_ttyp;
SESS_UNLOCK(p->p_session);
PROC_UNLOCK(p);
if (pca.tty == NULL) {
retval = 0;
goto out;
sx_sunlock(&proctree_lock);
return (0);
}
pca.flags = TOTTY;
pca.p_bufr = NULL;
va_start(ap, fmt);
tty_lock(pca.tty);
sx_sunlock(&proctree_lock);
retval = kvprintf(fmt, putchar, &pca, 10, ap);
tty_unlock(pca.tty);
va_end(ap);
out:
sx_sunlock(&proctree_lock);
return (retval);
}
@ -219,13 +218,13 @@ vtprintf(struct proc *p, int pri, const char *fmt, va_list ap)
pca.p_bufr = NULL;
if (pca.tty != NULL)
tty_lock(pca.tty);
sx_sunlock(&proctree_lock);
kvprintf(fmt, putchar, &pca, 10, ap);
if (pca.tty != NULL)
tty_unlock(pca.tty);
if (sess != NULL)
sess_release(sess);
msgbuftrigger = 1;
sx_sunlock(&proctree_lock);
}
/*