Author: kib
Date: Tue Oct 27 10:42:24 2009
New Revision: 198506
URL: http://svn.freebsd.org/changeset/base/198506
Log:
In kern_sigsuspend(), better manipulate thread signal mask using
kern_sigprocmask() to properly notify other possible candidate threads
for signal delivery.
Since sigsuspend() shall only return to usermode after a signal was
delivered, do cursig/postsig loop immediately after waiting for
signal, repeating the wait if wakeup was spurious due to race with
other thread fetching signal from the process queue before us. Add
thread_suspend_check() call to allow the thread to be stopped or killed
while in loop.
Modify last argument of kern_sigprocmask() from boolean to flags,
allowing the function to be called with locked proc. Convertion of the
callers that supplied 1 to the old argument will be done in the next
commit, and due to SIGPROCMASK_OLD value equial to 1, code is formally
correct in between.
Reviewed by: davidxu
Tested by: pho
MFC after: 1 month
Modified:
head/sys/compat/freebsd32/freebsd32_misc.c
head/sys/kern/kern_sig.c
head/sys/sys/signalvar.h
head/sys/sys/syscallsubr.h
Modified: head/sys/compat/freebsd32/freebsd32_misc.c
==============================================================================
--- head/sys/compat/freebsd32/freebsd32_misc.c Tue Oct 27 10:15:58 2009
(r198505)
+++ head/sys/compat/freebsd32/freebsd32_misc.c Tue Oct 27 10:42:24 2009
(r198506)
@@ -2579,21 +2579,10 @@ int
ofreebsd32_sigsuspend(struct thread *td,
struct ofreebsd32_sigsuspend_args *uap)
{
- struct proc *p = td->td_proc;
sigset_t mask;
- PROC_LOCK(p);
- td->td_oldsigmask = td->td_sigmask;
- td->td_pflags |= TDP_OLDMASK;
OSIG2SIG(uap->mask, mask);
- SIG_CANTMASK(mask);
- SIGSETLO(td->td_sigmask, mask);
- signotify(td);
- while (msleep(&p->p_sigacts, &p->p_mtx, PPAUSE|PCATCH, "opause", 0) ==
0)
- /* void */;
- PROC_UNLOCK(p);
- /* always return EINTR rather than ERESTART... */
- return (EINTR);
+ return (kern_sigsuspend(td, mask));
}
struct sigstack32 {
Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c Tue Oct 27 10:15:58 2009 (r198505)
+++ head/sys/kern/kern_sig.c Tue Oct 27 10:42:24 2009 (r198506)
@@ -970,14 +970,15 @@ execsigs(struct proc *p)
*/
int
kern_sigprocmask(struct thread *td, int how, sigset_t *set, sigset_t *oset,
- int old)
+ int flags)
{
sigset_t new_block, oset1;
struct proc *p;
int error;
p = td->td_proc;
- PROC_LOCK(p);
+ if (!(flags & SIGPROCMASK_PROC_LOCKED))
+ PROC_LOCK(p);
if (oset != NULL)
*oset = td->td_sigmask;
@@ -999,7 +1000,7 @@ kern_sigprocmask(struct thread *td, int
case SIG_SETMASK:
SIG_CANTMASK(*set);
oset1 = td->td_sigmask;
- if (old)
+ if (flags & SIGPROCMASK_OLD)
SIGSETLO(td->td_sigmask, *set);
else
td->td_sigmask = *set;
@@ -1025,7 +1026,8 @@ kern_sigprocmask(struct thread *td, int
if (p->p_numthreads != 1)
reschedule_signals(p, new_block);
- PROC_UNLOCK(p);
+ if (!(flags & SIGPROCMASK_PROC_LOCKED))
+ PROC_UNLOCK(p);
return (error);
}
@@ -1458,6 +1460,7 @@ int
kern_sigsuspend(struct thread *td, sigset_t mask)
{
struct proc *p = td->td_proc;
+ int has_sig, sig;
/*
* When returning from sigsuspend, we want
@@ -1467,13 +1470,28 @@ kern_sigsuspend(struct thread *td, sigse
* to indicate this.
*/
PROC_LOCK(p);
- td->td_oldsigmask = td->td_sigmask;
+ kern_sigprocmask(td, SIG_SETMASK, &mask, &td->td_oldsigmask,
+ SIGPROCMASK_PROC_LOCKED);
td->td_pflags |= TDP_OLDMASK;
- SIG_CANTMASK(mask);
- td->td_sigmask = mask;
- signotify(td);
- while (msleep(&p->p_sigacts, &p->p_mtx, PPAUSE|PCATCH, "pause", 0) == 0)
- /* void */;
+
+ /*
+ * Process signals now. Otherwise, we can get spurious wakeup
+ * due to signal entered process queue, but delivered to other
+ * thread. But sigsuspend should return only on signal
+ * delivery.
+ */
+ for (has_sig = 0; !has_sig;) {
+ while (msleep(&p->p_sigacts, &p->p_mtx, PPAUSE|PCATCH, "pause",
+ 0) == 0)
+ /* void */;
+ thread_suspend_check(0);
+ mtx_lock(&p->p_sigacts->ps_mtx);
+ while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0) {
+ postsig(sig);
+ has_sig = 1;
+ }
+ mtx_unlock(&p->p_sigacts->ps_mtx);
+ }
PROC_UNLOCK(p);
/* always return EINTR rather than ERESTART... */
return (EINTR);
@@ -1495,21 +1513,10 @@ osigsuspend(td, uap)
struct thread *td;
struct osigsuspend_args *uap;
{
- struct proc *p = td->td_proc;
sigset_t mask;
- PROC_LOCK(p);
- td->td_oldsigmask = td->td_sigmask;
- td->td_pflags |= TDP_OLDMASK;
OSIG2SIG(uap->mask, mask);
- SIG_CANTMASK(mask);
- SIGSETLO(td->td_sigmask, mask);
- signotify(td);
- while (msleep(&p->p_sigacts, &p->p_mtx, PPAUSE|PCATCH, "opause", 0) ==
0)
- /* void */;
- PROC_UNLOCK(p);
- /* always return EINTR rather than ERESTART... */
- return (EINTR);
+ return (kern_sigsuspend(td, mask));
}
#endif /* COMPAT_43 */
Modified: head/sys/sys/signalvar.h
==============================================================================
--- head/sys/sys/signalvar.h Tue Oct 27 10:15:58 2009 (r198505)
+++ head/sys/sys/signalvar.h Tue Oct 27 10:42:24 2009 (r198506)
@@ -316,6 +316,10 @@ extern int kern_logsigexit; /* Sysctl va
#define SIG_STOP_ALLOWED 100
#define SIG_STOP_NOT_ALLOWED 101
+/* flags for kern_sigprocmask */
+#define SIGPROCMASK_OLD 0x0001
+#define SIGPROCMASK_PROC_LOCKED 0x0002
+
/*
* Machine-independent functions:
*/
@@ -359,7 +363,8 @@ void sigqueue_delete_stopmask_proc(struc
void sigqueue_take(ksiginfo_t *ksi);
int kern_sigtimedwait(struct thread *, sigset_t,
ksiginfo_t *, struct timespec *);
-
+int kern_sigprocmask(struct thread *td, int how,
+ sigset_t *set, sigset_t *oset, int flags);
/*
* Machine-dependent functions:
*/
Modified: head/sys/sys/syscallsubr.h
==============================================================================
--- head/sys/sys/syscallsubr.h Tue Oct 27 10:15:58 2009 (r198505)
+++ head/sys/sys/syscallsubr.h Tue Oct 27 10:42:24 2009 (r198506)
@@ -190,8 +190,6 @@ int kern_shmctl(struct thread *td, int s
int kern_sigaction(struct thread *td, int sig, struct sigaction *act,
struct sigaction *oact, int flags);
int kern_sigaltstack(struct thread *td, stack_t *ss, stack_t *oss);
-int kern_sigprocmask(struct thread *td, int how,
- sigset_t *set, sigset_t *oset, int old);
int kern_sigsuspend(struct thread *td, sigset_t mask);
int kern_stat(struct thread *td, char *path, enum uio_seg pathseg,
struct stat *sbp);
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