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The previous commit wasn't entirely correct. At least one goto to the

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out: label in psignal() did not grab sched_lock before trying to release
it.  Also, the previous version had several cases where it grabbed
sched_lock before jumping to out: unneccessarily, so rework this a bit.
The runfast: and out: labels must be called with sched_lock released, and
the run: label must be called with it held.  Appropriate mtx_assert()'s
have been added that should catch any bugs that may still be in this
code.

Noticed by:	bde
This commit is contained in:
John Baldwin 2001-01-02 18:54:09 +00:00
parent 542e394c1c
commit 3e6831f510
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=70603
1 changed files with 22 additions and 18 deletions
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38
sys/kern/kern_sig.c
View File

@ -1123,8 +1123,10 @@ psignal(p, sig)
* be noticed when the process returns through
* trap() or syscall().
*/
if ((p->p_flag & P_SINTR) == 0)
if ((p->p_flag & P_SINTR) == 0) {
mtx_exit(&sched_lock, MTX_SPIN);
goto out;
}
/*
* Process is sleeping and traced... make it runnable
* so it can discover the signal in issignal() and stop
@ -1132,15 +1134,14 @@ psignal(p, sig)
*/
if (p->p_flag & P_TRACED)
goto run;
mtx_exit(&sched_lock, MTX_SPIN);
/*
* If SIGCONT is default (or ignored) and process is
* asleep, we are finished; the process should not
* be awakened.
*/
mtx_exit(&sched_lock, MTX_SPIN);
if ((prop & SA_CONT) && action == SIG_DFL) {
SIGDELSET(p->p_siglist, sig);
mtx_enter(&sched_lock, MTX_SPIN);
goto out;
}
/*
@ -1150,10 +1151,8 @@ psignal(p, sig)
* cause the process to run.
*/
if (prop & SA_STOP) {
if (action != SIG_DFL) {
mtx_enter(&sched_lock, MTX_SPIN);
if (action != SIG_DFL)
goto runfast;
}
/*
* If a child holding parent blocked,
* stopping could cause deadlock.
@ -1167,12 +1166,9 @@ psignal(p, sig)
psignal(p->p_pptr, SIGCHLD);
stop(p);
PROCTREE_LOCK(PT_RELEASE);
mtx_enter(&sched_lock, MTX_SPIN);
goto out;
} else {
mtx_enter(&sched_lock, MTX_SPIN);
} else
goto runfast;
}
/* NOTREACHED */
case SSTOP:
@ -1180,8 +1176,11 @@ psignal(p, sig)
* If traced process is already stopped,
* then no further action is necessary.
*/
if (p->p_flag & P_TRACED)
if (p->p_flag & P_TRACED) {
mtx_exit(&sched_lock, MTX_SPIN);
goto out;
}
mtx_exit(&sched_lock, MTX_SPIN);
/*
* Kill signal always sets processes running.
@ -1189,7 +1188,6 @@ psignal(p, sig)
if (sig == SIGKILL)
goto runfast;
mtx_exit(&sched_lock, MTX_SPIN);
if (prop & SA_CONT) {
/*
* If SIGCONT is default (or ignored), we continue the
@ -1203,12 +1201,13 @@ psignal(p, sig)
*/
if (action == SIG_DFL)
SIGDELSET(p->p_siglist, sig);
mtx_enter(&sched_lock, MTX_SPIN);
if (action == SIG_CATCH)
goto runfast;
mtx_enter(&sched_lock, MTX_SPIN);
if (p->p_wchan == 0)
goto run;
p->p_stat = SSLEEP;
mtx_exit(&sched_lock, MTX_SPIN);
goto out;
}
@ -1218,7 +1217,6 @@ psignal(p, sig)
* (If we did the shell could get confused.)
*/
SIGDELSET(p->p_siglist, sig);
mtx_enter(&sched_lock, MTX_SPIN);
goto out;
}
@ -1231,6 +1229,7 @@ psignal(p, sig)
mtx_enter(&sched_lock, MTX_SPIN);
if (p->p_wchan && p->p_flag & P_SINTR)
unsleep(p);
mtx_exit(&sched_lock, MTX_SPIN);
goto out;
default:
@ -1242,15 +1241,15 @@ psignal(p, sig)
if (p == curproc) {
mtx_exit(&sched_lock, MTX_SPIN);
signotify(p);
mtx_enter(&sched_lock, MTX_SPIN);
}
#ifdef SMP
else if (p->p_stat == SRUN) {
mtx_exit(&sched_lock, MTX_SPIN);
forward_signal(p);
mtx_enter(&sched_lock, MTX_SPIN);
}
#endif
else
mtx_exit(&sched_lock, MTX_SPIN);
goto out;
}
/*NOTREACHED*/
@ -1259,12 +1258,17 @@ psignal(p, sig)
/*
* Raise priority to at least PUSER.
*/
mtx_enter(&sched_lock, MTX_SPIN);
if (p->p_priority > PUSER)
p->p_priority = PUSER;
run:
/* If we jump here, sched_lock has to be owned. */
mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
setrunnable(p);
out:
mtx_exit(&sched_lock, MTX_SPIN);
out:
/* If we jump here, sched_lock should not be owned. */
mtx_assert(&sched_lock, MA_NOTOWNED);
splx(s);
}