Commit 8677347378044ab564470bced2275520efb3670d
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9843a1e977
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make do_notify_parent() __must_check, update the callers
Change other callers of do_notify_parent() to check the value it returns, this makes the subsequent task_detached() unnecessary. Mark do_notify_parent() as __must_check. Use thread_group_leader() instead of !task_detached() to check if we need to notify the real parent in wait_task_zombie(). Remove the stale comment in release_task(). "just for sanity" is no longer true, we have to set EXIT_DEAD to avoid the races with do_wait(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Tejun Heo <tj@kernel.org>
Showing 2 changed files with 9 additions and 22 deletions Side-by-side Diff
include/linux/sched.h
| ... | ... | @@ -2160,7 +2160,7 @@ |
| 2160 | 2160 | extern int kill_pgrp(struct pid *pid, int sig, int priv); |
| 2161 | 2161 | extern int kill_pid(struct pid *pid, int sig, int priv); |
| 2162 | 2162 | extern int kill_proc_info(int, struct siginfo *, pid_t); |
| 2163 | -extern bool do_notify_parent(struct task_struct *, int); | |
| 2163 | +extern __must_check bool do_notify_parent(struct task_struct *, int); | |
| 2164 | 2164 | extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent); |
| 2165 | 2165 | extern void force_sig(int, struct task_struct *); |
| 2166 | 2166 | extern int send_sig(int, struct task_struct *, int); |
kernel/exit.c
| ... | ... | @@ -190,21 +190,12 @@ |
| 190 | 190 | leader = p->group_leader; |
| 191 | 191 | if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { |
| 192 | 192 | BUG_ON(task_detached(leader)); |
| 193 | - do_notify_parent(leader, leader->exit_signal); | |
| 194 | 193 | /* |
| 195 | 194 | * If we were the last child thread and the leader has |
| 196 | 195 | * exited already, and the leader's parent ignores SIGCHLD, |
| 197 | 196 | * then we are the one who should release the leader. |
| 198 | - * | |
| 199 | - * do_notify_parent() will have marked it self-reaping in | |
| 200 | - * that case. | |
| 201 | 197 | */ |
| 202 | - zap_leader = task_detached(leader); | |
| 203 | - | |
| 204 | - /* | |
| 205 | - * This maintains the invariant that release_task() | |
| 206 | - * only runs on a task in EXIT_DEAD, just for sanity. | |
| 207 | - */ | |
| 198 | + zap_leader = do_notify_parent(leader, leader->exit_signal); | |
| 208 | 199 | if (zap_leader) |
| 209 | 200 | leader->exit_state = EXIT_DEAD; |
| 210 | 201 | } |
| ... | ... | @@ -766,8 +757,7 @@ |
| 766 | 757 | /* If it has exited notify the new parent about this child's death. */ |
| 767 | 758 | if (!p->ptrace && |
| 768 | 759 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
| 769 | - do_notify_parent(p, p->exit_signal); | |
| 770 | - if (task_detached(p)) { | |
| 760 | + if (do_notify_parent(p, p->exit_signal)) { | |
| 771 | 761 | p->exit_state = EXIT_DEAD; |
| 772 | 762 | list_move_tail(&p->sibling, dead); |
| 773 | 763 | } |
| 774 | 764 | |
| ... | ... | @@ -1351,16 +1341,13 @@ |
| 1351 | 1341 | /* We dropped tasklist, ptracer could die and untrace */ |
| 1352 | 1342 | ptrace_unlink(p); |
| 1353 | 1343 | /* |
| 1354 | - * If this is not a detached task, notify the parent. | |
| 1355 | - * If it's still not detached after that, don't release | |
| 1356 | - * it now. | |
| 1344 | + * If this is not a sub-thread, notify the parent. | |
| 1345 | + * If parent wants a zombie, don't release it now. | |
| 1357 | 1346 | */ |
| 1358 | - if (!task_detached(p)) { | |
| 1359 | - do_notify_parent(p, p->exit_signal); | |
| 1360 | - if (!task_detached(p)) { | |
| 1361 | - p->exit_state = EXIT_ZOMBIE; | |
| 1362 | - p = NULL; | |
| 1363 | - } | |
| 1347 | + if (thread_group_leader(p) && | |
| 1348 | + !do_notify_parent(p, p->exit_signal)) { | |
| 1349 | + p->exit_state = EXIT_ZOMBIE; | |
| 1350 | + p = NULL; | |
| 1364 | 1351 | } |
| 1365 | 1352 | write_unlock_irq(&tasklist_lock); |
| 1366 | 1353 | } |