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authorEric W. Biederman <ebiederm@xmission.com>2022-06-21 14:38:52 -0500
committerEric W. Biederman <ebiederm@xmission.com>2022-07-20 10:23:51 -0500
commitd80f7d7b2c75c5954d335dffbccca62a5002c3e0 (patch)
tree323d202b5875f926c9b35f660ed3c1aa6334183d /kernel/exit.c
parentcbe9dac379047730e39c7e570eddd27124b0d2dc (diff)
signal: Guarantee that SIGNAL_GROUP_EXIT is set on process exit
Track how many threads have not started exiting and when the last thread starts exiting set SIGNAL_GROUP_EXIT. This guarantees that SIGNAL_GROUP_EXIT will get set when a process exits. In practice this achieves nothing as glibc's implementation of _exit calls sys_group_exit then sys_exit. While glibc's implemenation of pthread_exit calls exit (which cleansup and calls _exit) if it is the last thread and sys_exit if it is the last thread. This means the only way the kernel might observe a process that does not set call exit_group is if the language runtime does not use glibc. With more cleanups I hope to move the decrement of quick_threads earlier. Link: https://lkml.kernel.org/r/87bkukd4tc.fsf_-_@email.froward.int.ebiederm.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index a3929e5e6d61..d8ecbaa514f7 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -733,11 +733,29 @@ static void check_stack_usage(void)
static inline void check_stack_usage(void) {}
#endif
+static void synchronize_group_exit(struct task_struct *tsk, long code)
+{
+ struct sighand_struct *sighand = tsk->sighand;
+ struct signal_struct *signal = tsk->signal;
+
+ spin_lock_irq(&sighand->siglock);
+ signal->quick_threads--;
+ if ((signal->quick_threads == 0) &&
+ !(signal->flags & SIGNAL_GROUP_EXIT)) {
+ signal->flags = SIGNAL_GROUP_EXIT;
+ signal->group_exit_code = code;
+ signal->group_stop_count = 0;
+ }
+ spin_unlock_irq(&sighand->siglock);
+}
+
void __noreturn do_exit(long code)
{
struct task_struct *tsk = current;
int group_dead;
+ synchronize_group_exit(tsk, code);
+
WARN_ON(tsk->plug);
kcov_task_exit(tsk);