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authorOleg Nesterov <oleg@redhat.com>2009-09-23 15:56:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-24 07:20:59 -0700
commita7f0765edfd53aed09cb7b0e15863688b39447de (patch)
treec89adfe418f9988ad4044e0f22827458bdf6b155 /kernel/exit.c
parent1dd3a27326d307952f8ad2499478c84dc7311517 (diff)
ptrace: __ptrace_detach: do __wake_up_parent() if we reap the tracee
The bug is old, it wasn't cause by recent changes. Test case: static void *tfunc(void *arg) { int pid = (long)arg; assert(ptrace(PTRACE_ATTACH, pid, NULL, NULL) == 0); kill(pid, SIGKILL); sleep(1); return NULL; } int main(void) { pthread_t th; long pid = fork(); if (!pid) pause(); signal(SIGCHLD, SIG_IGN); assert(pthread_create(&th, NULL, tfunc, (void*)pid) == 0); int r = waitpid(-1, NULL, __WNOTHREAD); printf("waitpid: %d %m\n", r); return 0; } Before the patch this program hangs, after this patch waitpid() correctly fails with errno == -ECHILD. The problem is, __ptrace_detach() reaps the EXIT_ZOMBIE tracee if its ->real_parent is our sub-thread and we ignore SIGCHLD. But in this case we should wake up other threads which can sleep in do_wait(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: Vitaly Mayatskikh <vmayatsk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 60d6fdcc926..782b2e1f7ca 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1575,6 +1575,11 @@ static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
return 0;
}
+void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
+{
+ wake_up_interruptible_sync(&parent->signal->wait_chldexit);
+}
+
static long do_wait(struct wait_opts *wo)
{
DECLARE_WAITQUEUE(wait, current);