[PATCH 2/5] exit: move core of do_wait() into helper

Jens Axboe
2023-07-11T20:44:10Z

Rather than have a maze of gotos, put the actual logic in __do_wait()
and have do_wait() loop deal with waitqueue setup/teardown and whether
to call __do_wait() again.

No functional changes intended in this patch.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
kernel/exit.c | 49 ++++++++++++++++++++++++++++++-------------------
1 file changed, 30 insertions(+), 19 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index 2809dad69492..d8fb124cc038 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1590,16 +1590,10 @@ static int do_wait_pid(struct wait_opts *wo)
return 0;
}

-static long do_wait(struct wait_opts *wo)
+static long __do_wait(struct wait_opts *wo)
{
- int retval;
-
- trace_sched_process_wait(wo->wo_pid);
+ long retval;

- init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
- wo->child_wait.private = current;
- add_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
-repeat:
/*
* If there is nothing that can match our criteria, just get out.
* We will clear ->notask_error to zero if we see any child that
@@ -1617,18 +1611,18 @@ static long do_wait(struct wait_opts *wo)
if (wo->wo_type == PIDTYPE_PID) {
retval = do_wait_pid(wo);
if (retval)
- goto end;
+ return retval;
} else {
struct task_struct *tsk = current;

do {
retval = do_wait_thread(wo, tsk);
if (retval)
- goto end;
+ return retval;

retval = ptrace_do_wait(wo, tsk);
if (retval)
- goto end;
+ return retval;

if (wo->wo_flags & __WNOTHREAD)
break;
@@ -1638,14 +1632,31 @@ static long do_wait(struct wait_opts *wo)

notask:
retval = wo->notask_error;
- if (!retval && !(wo->wo_flags & WNOHANG)) {
- retval = -ERESTARTSYS;
- if (!signal_pending(current)) {
- schedule();
- goto repeat;
- }
- }
-end:
+ if (!retval && !(wo->wo_flags & WNOHANG))
+ return -ERESTARTSYS;
+
+ return retval;
+}
+
+static long do_wait(struct wait_opts *wo)
+{
+ int retval;
+
+ trace_sched_process_wait(wo->wo_pid);
+
+ init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
+ wo->child_wait.private = current;
+ add_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
+
+ do {
+ retval = __do_wait(wo);
+ if (retval != -ERESTARTSYS)
+ break;
+ if (signal_pending(current))
+ break;
+ schedule();
+ } while (1);
+
__set_current_state(TASK_RUNNING);
remove_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
return retval;
--
2.40.1