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author | jhb <jhb@FreeBSD.org> | 2007-05-14 22:21:58 +0000 |
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committer | jhb <jhb@FreeBSD.org> | 2007-05-14 22:21:58 +0000 |
commit | 77d161b46b5af0e16571ad43b660bcafb3bc3039 (patch) | |
tree | b157dbdf4d94b30f7dfc04ac706e1552547a31e8 /sys/kern | |
parent | 2b1170b7f0d8d7f8db62041decf2e8933d65441d (diff) | |
download | FreeBSD-src-77d161b46b5af0e16571ad43b660bcafb3bc3039.zip FreeBSD-src-77d161b46b5af0e16571ad43b660bcafb3bc3039.tar.gz |
Move cpu_exit() earlier in exit1() to close a race between
SIGCHLD/kevent(2) notification of process termination and wait(). Now
we no longer drop locks between sending the notification and marking
the process as a zombie. Previously, if another process attempted to do
a wait() with W_NOHANG after receiving a SIGCHLD or kevent and locked
the process while the exiting thread was in cpu_exit(), then wait() would
fail to find the process, which is quite astonishing to the process
calling wait().
MFC after: 3 days
Diffstat (limited to 'sys/kern')
-rw-r--r-- | sys/kern/kern_exit.c | 26 |
1 files changed, 10 insertions, 16 deletions
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c index 1d60fe7..029fe3a 100644 --- a/sys/kern/kern_exit.c +++ b/sys/kern/kern_exit.c @@ -406,6 +406,16 @@ retry: sx_xunlock(&allproc_lock); /* + * Call machine-dependent code to release any + * machine-dependent resources other than the address space. + * The address space is released by "vmspace_exitfree(p)" in + * vm_waitproc(). + */ + cpu_exit(td); + + WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid); + + /* * Reparent all of our children to init. */ sx_xlock(&proctree_lock); @@ -484,22 +494,6 @@ retry: else /* LINUX thread */ psignal(p->p_pptr, p->p_sigparent); } - PROC_UNLOCK(p->p_pptr); - PROC_UNLOCK(p); - - /* - * Finally, call machine-dependent code to release the remaining - * resources including address space. - * The address space is released by "vmspace_exitfree(p)" in - * vm_waitproc(). - */ - cpu_exit(td); - - WITNESS_WARN(WARN_PANIC, &proctree_lock.lock_object, - "process (pid %d) exiting", p->p_pid); - - PROC_LOCK(p); - PROC_LOCK(p->p_pptr); sx_xunlock(&proctree_lock); /* |