diff options
| author | Visa Hankala <visa@cvs.openbsd.org> | 2018-07-07 15:19:26 +0000 |
|---|---|---|
| committer | Visa Hankala <visa@cvs.openbsd.org> | 2018-07-07 15:19:26 +0000 |
| commit | 8057647d9610ac9017742fe97f823b4dc5c40538 (patch) | |
| tree | a7c1251f0c1d3c5335862b7ac95f5150bfdb722b /sys/kern/kern_sched.c | |
| parent | 19c8d8ab4c5fd7687547983f4cc64ad0144abe85 (diff) | |
Release the kernel lock fully on thread exit. This prevents a locking
error that would happen otherwise when a traced and stopped
multithreaded process is forced to exit. The error shows up as a kernel
panic when WITNESS is enabled. Without WITNESS, the error causes
a system hang.
sched_exit() has expected that a single KERNEL_UNLOCK() would release
the lock completely. That assumption is wrong when an exit happens
through the signal tracing logic:
sched_exit
exit1
single_thread_check
single_thread_set
issignal <-- KERNEL_LOCK()
userret <-- KERNEL_LOCK()
syscall
The error is a regression of r1.216 of kern_sig.c.
Panic reported and fix tested by Laurence Tratt
OK mpi@
Diffstat (limited to 'sys/kern/kern_sched.c')
| -rw-r--r-- | sys/kern/kern_sched.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c index 9de421f037a..4309255ca9d 100644 --- a/sys/kern/kern_sched.c +++ b/sys/kern/kern_sched.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kern_sched.c,v 1.49 2018/06/30 14:43:36 kettenis Exp $ */ +/* $OpenBSD: kern_sched.c,v 1.50 2018/07/07 15:19:25 visa Exp $ */ /* * Copyright (c) 2007, 2008 Artur Grabowski <art@openbsd.org> * @@ -218,8 +218,11 @@ sched_exit(struct proc *p) LIST_INSERT_HEAD(&spc->spc_deadproc, p, p_hash); +#ifdef MULTIPROCESSOR /* This process no longer needs to hold the kernel lock. */ - KERNEL_UNLOCK(); + KERNEL_ASSERT_LOCKED(); + __mp_release_all(&kernel_lock); +#endif SCHED_LOCK(s); idle = spc->spc_idleproc; |