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author | Roland McGrath <roland@redhat.com> | 2005-01-04 05:38:42 -0800 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-01-04 05:38:42 -0800 |
commit | 6ba7b420d6943a76ef777b2de26c37ad0daf212a (patch) | |
tree | ef1a0cdc8c8911c4d81574739c2a211c7bb40c67 /kernel | |
parent | 10d6e374ae2e96a43033cf7cf289e0411cf25fe7 (diff) | |
download | history-6ba7b420d6943a76ef777b2de26c37ad0daf212a.tar.gz |
[PATCH] task_struct.exit_state usage
I just did a quick audit of the use of exit_state and the EXIT_* bit
macros. I guess I didn't really review these changes very closely when you
did them originally. :-(
I found several places that seem like lossy cases of query-replace without
enough thought about the code. Linus has previously said the >= tests
ought to be & tests instead. But for exit_state, it can only ever be 0,
EXIT_DEAD, or EXIT_ZOMBIE--so a nonzero test is actually the same as
testing & (EXIT_DEAD|EXIT_ZOMBIE), and maybe its code is a tiny bit better.
The case like in choose_new_parent is just confusing, to have the
always-false test for EXIT_* bits in ->state there too.
The two cases in wants_signal and do_process_times are actual regressions
that will give us back old bugs in race conditions. These places had
s/TASK/EXIT/ but not s/state/exit_state/, and now there tests for exiting
tasks are now wrong and never catching them. I take it back: there is no
regression in wants_signal in practice I think, because of the PF_EXITING
test that makes the EXIT_* state checks superfluous anyway. So that is
just another cosmetic case of confusing code. But in do_process_times,
there is that SIGXCPU-while-exiting race condition back again.
Signed-off-by: Roland McGrath <roland@redhat.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/exit.c | 8 | ||||
-rw-r--r-- | kernel/sched.c | 2 | ||||
-rw-r--r-- | kernel/signal.c | 6 | ||||
-rw-r--r-- | kernel/timer.c | 2 |
4 files changed, 9 insertions, 9 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index d7b09c996f6d58..f6b64f9e3dcc4c 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -159,7 +159,7 @@ static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task) do_each_task_pid(pgrp, PIDTYPE_PGID, p) { if (p == ignored_task - || p->exit_state >= EXIT_ZOMBIE + || p->exit_state || p->real_parent->pid == 1) continue; if (process_group(p->real_parent) != pgrp @@ -517,7 +517,7 @@ static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_re * Make sure we're not reparenting to ourselves and that * the parent is not a zombie. */ - BUG_ON(p == reaper || reaper->state >= EXIT_ZOMBIE || reaper->exit_state >= EXIT_ZOMBIE); + BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE); p->real_parent = reaper; if (p->parent == p->real_parent) BUG(); @@ -599,7 +599,7 @@ static inline void forget_original_parent(struct task_struct * father, reaper = child_reaper; break; } - } while (reaper->exit_state >= EXIT_ZOMBIE); + } while (reaper->exit_state); /* * There are only two places where our children can be: @@ -1182,7 +1182,7 @@ static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap, * race with the EXIT_ZOMBIE case. */ exit_code = xchg(&p->exit_code, 0); - if (unlikely(p->exit_state >= EXIT_ZOMBIE)) { + if (unlikely(p->exit_state)) { /* * The task resumed and then died. Let the next iteration * catch it in EXIT_ZOMBIE. Note that exit_code might diff --git a/kernel/sched.c b/kernel/sched.c index 3386e7b876143f..9f1e93a2bf0efb 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2541,7 +2541,7 @@ asmlinkage void __sched schedule(void) * schedule() atomically, we ignore that path for now. * Otherwise, whine if we are scheduling when we should not be. */ - if (likely(!(current->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)))) { + if (likely(!current->exit_state)) { if (unlikely(in_atomic())) { printk(KERN_ERR "scheduling while atomic: " "%s/0x%08x/%d\n", diff --git a/kernel/signal.c b/kernel/signal.c index 7191de92659bf5..85ad9a0ae3f155 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -934,10 +934,10 @@ __group_complete_signal(int sig, struct task_struct *p) struct task_struct *t; /* - * Don't bother zombies and stopped tasks (but + * Don't bother traced and stopped tasks (but * SIGKILL will punch through stopped state) */ - mask = EXIT_DEAD | EXIT_ZOMBIE | TASK_TRACED; + mask = TASK_TRACED; if (sig != SIGKILL) mask |= TASK_STOPPED; @@ -1094,7 +1094,7 @@ void zap_other_threads(struct task_struct *p) /* * Don't bother with already dead threads */ - if (t->exit_state & (EXIT_ZOMBIE|EXIT_DEAD)) + if (t->exit_state) continue; /* diff --git a/kernel/timer.c b/kernel/timer.c index d0eed9b563c48b..d0177a7f573a18 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -806,7 +806,7 @@ static inline void do_process_times(struct task_struct *p, psecs = (p->utime += user); psecs += (p->stime += system); - if (p->signal && !unlikely(p->state & (EXIT_DEAD|EXIT_ZOMBIE)) && + if (p->signal && !unlikely(p->exit_state) && psecs / HZ >= p->signal->rlim[RLIMIT_CPU].rlim_cur) { /* Send SIGXCPU every second.. */ if (!(psecs % HZ)) |