Author: kib
Date: Fri Oct 30 10:10:39 2009
New Revision: 198670
URL: http://svn.freebsd.org/changeset/base/198670
Log:
Trapsignal() and postsig() call kern_sigprocmask() with both process
lock and curproc->p_sigacts->ps_mtx. Reschedule_signals may need to have
ps_mtx locked to decide and wakeup a thread, causing recursion on the
mutex.
Inform kern_sigprocmask() and reschedule_signals() about lock state
of the ps_mtx by new flag SIGPROCMASK_PS_LOCKED to avoid recursion.
Reported and tested by: keramida
MFC after: 1 month
Modified:
head/sys/kern/kern_sig.c
head/sys/sys/signalvar.h
Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c Fri Oct 30 08:53:11 2009 (r198669)
+++ head/sys/kern/kern_sig.c Fri Oct 30 10:10:39 2009 (r198670)
@@ -220,7 +220,7 @@ static int sigproptbl[NSIG] = {
SA_KILL|SA_PROC, /* SIGUSR2 */
};
-static void reschedule_signals(struct proc *p, sigset_t block);
+static void reschedule_signals(struct proc *p, sigset_t block, int flags);
static void
sigqueue_start(void)
@@ -1024,7 +1024,7 @@ kern_sigprocmask(struct thread *td, int
* possibly waking it up.
*/
if (p->p_numthreads != 1)
- reschedule_signals(p, new_block);
+ reschedule_signals(p, new_block, flags);
if (!(flags & SIGPROCMASK_PROC_LOCKED))
PROC_UNLOCK(p);
@@ -1859,13 +1859,11 @@ trapsignal(struct thread *td, ksiginfo_t
#endif
(*p->p_sysent->sv_sendsig)(ps->ps_sigact[_SIG_IDX(sig)],
ksi, &td->td_sigmask);
- SIGSETOR(td->td_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
- if (!SIGISMEMBER(ps->ps_signodefer, sig)) {
- SIGEMPTYSET(mask);
+ mask = ps->ps_catchmask[_SIG_IDX(sig)];
+ if (!SIGISMEMBER(ps->ps_signodefer, sig))
SIGADDSET(mask, sig);
- kern_sigprocmask(td, SIG_BLOCK, &mask, NULL,
- SIGPROCMASK_PROC_LOCKED);
- }
+ kern_sigprocmask(td, SIG_BLOCK, &mask, NULL,
+ SIGPROCMASK_PROC_LOCKED | SIGPROCMASK_PS_LOCKED);
if (SIGISMEMBER(ps->ps_sigreset, sig)) {
/*
* See kern_sigaction() for origin of this code.
@@ -2401,7 +2399,7 @@ stopme:
}
static void
-reschedule_signals(struct proc *p, sigset_t block)
+reschedule_signals(struct proc *p, sigset_t block, int flags)
{
struct sigacts *ps;
struct thread *td;
@@ -2419,12 +2417,14 @@ reschedule_signals(struct proc *p, sigse
td = sigtd(p, i, 0);
signotify(td);
- mtx_lock(&ps->ps_mtx);
+ if (!(flags & SIGPROCMASK_PS_LOCKED))
+ mtx_lock(&ps->ps_mtx);
if (p->p_flag & P_TRACED || SIGISMEMBER(ps->ps_sigcatch, i))
tdsigwakeup(td, i, SIG_CATCH,
(SIGISMEMBER(ps->ps_sigintr, i) ? EINTR :
ERESTART));
- mtx_unlock(&ps->ps_mtx);
+ if (!(flags & SIGPROCMASK_PS_LOCKED))
+ mtx_unlock(&ps->ps_mtx);
}
}
@@ -2452,7 +2452,7 @@ tdsigcleanup(struct thread *td)
SIGFILLSET(unblocked);
SIGSETNAND(unblocked, td->td_sigmask);
SIGFILLSET(td->td_sigmask);
- reschedule_signals(p, unblocked);
+ reschedule_signals(p, unblocked, 0);
}
@@ -2734,15 +2734,11 @@ postsig(sig)
} else
returnmask = td->td_sigmask;
- kern_sigprocmask(td, SIG_BLOCK,
- &ps->ps_catchmask[_SIG_IDX(sig)], NULL,
- SIGPROCMASK_PROC_LOCKED);
- if (!SIGISMEMBER(ps->ps_signodefer, sig)) {
- SIGEMPTYSET(mask);
+ mask = ps->ps_catchmask[_SIG_IDX(sig)];
+ if (!SIGISMEMBER(ps->ps_signodefer, sig))
SIGADDSET(mask, sig);
- kern_sigprocmask(td, SIG_BLOCK, &mask, NULL,
- SIGPROCMASK_PROC_LOCKED);
- }
+ kern_sigprocmask(td, SIG_BLOCK, &mask, NULL,
+ SIGPROCMASK_PROC_LOCKED | SIGPROCMASK_PS_LOCKED);
if (SIGISMEMBER(ps->ps_sigreset, sig)) {
/*
Modified: head/sys/sys/signalvar.h
==============================================================================
--- head/sys/sys/signalvar.h Fri Oct 30 08:53:11 2009 (r198669)
+++ head/sys/sys/signalvar.h Fri Oct 30 10:10:39 2009 (r198670)
@@ -319,6 +319,7 @@ extern int kern_logsigexit; /* Sysctl va
/* flags for kern_sigprocmask */
#define SIGPROCMASK_OLD 0x0001
#define SIGPROCMASK_PROC_LOCKED 0x0002
+#define SIGPROCMASK_PS_LOCKED 0x0004
/*
* Machine-independent functions:
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