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[PATCH] taskstats: kill ->taskstats_lock in favor of ->siglock

signal_struct is (mostly) protected by ->sighand->siglock, I think we don't need ->taskstats_lock to protect ->stats. This also allows us to simplify the locking in fill_tgid().

Oleg Nesterov committed 20 years ago

Commit b8534d71 parent 17b02694 files · +13 −21Browse files

Showing the changes to kernel (2 of 4 files). Show all

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2 files
  1. kernel/fork.c +1 −1
  2. kernel/taskstats.c +6 −10
kernel/fork.c+1−1
@@ -830,7 +830,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts · 829 unmodified lines
830 if (clone_flags & CLONE_THREAD) {830 if (clone_flags & CLONE_THREAD) {
831 atomic_inc(&current->signal->count);831 atomic_inc(&current->signal->count);
832 atomic_inc(&current->signal->live);832 atomic_inc(&current->signal->live);
833 taskstats_tgid_alloc(current->signal);833 taskstats_tgid_alloc(current);
834 return 0;834 return 0;
835 }835 }
836 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);836 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
kernel/taskstats.c+6−10
@@ -241,11 +241,11 @@ static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk, · 240 unmodified lines
241 tsk = first;241 tsk = first;
242 read_lock(&tasklist_lock);242 read_lock(&tasklist_lock);
243 /* Start with stats from dead tasks */243 /* Start with stats from dead tasks */
244 if (first->signal) {244 if (first->sighand) {
245 spin_lock_irqsave(&first->signal->stats_lock, flags);245 spin_lock_irqsave(&first->sighand->siglock, flags);
246 if (first->signal->stats)246 if (first->signal->stats)
247 memcpy(stats, first->signal->stats, sizeof(*stats));247 memcpy(stats, first->signal->stats, sizeof(*stats));
248 spin_unlock_irqrestore(&first->signal->stats_lock, flags);248 spin_unlock_irqrestore(&first->sighand->siglock, flags);
249 }249 }
250 250
251 do {251 do {
@@ -276,7 +276,7 @@ static void fill_tgid_exit(struct task_struct *tsk) · 24 unmodified lines
276{276{
277 unsigned long flags;277 unsigned long flags;
278 278
279 spin_lock_irqsave(&tsk->signal->stats_lock, flags);279 spin_lock_irqsave(&tsk->sighand->siglock, flags);
280 if (!tsk->signal->stats)280 if (!tsk->signal->stats)
281 goto ret;281 goto ret;
282 282
@@ -288,7 +288,7 @@ static void fill_tgid_exit(struct task_struct *tsk) · 5 unmodified lines
288 */288 */
289 delayacct_add_tsk(tsk->signal->stats, tsk);289 delayacct_add_tsk(tsk->signal->stats, tsk);
290ret:290ret:
291 spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);291 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
292 return;292 return;
293}293}
294 294
@@ -464,15 +464,10 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats, · 169 unmodified lines
464 size_t size;464 size_t size;
465 int is_thread_group;465 int is_thread_group;
466 struct nlattr *na;466 struct nlattr *na;
467 unsigned long flags;
468 467
469 if (!family_registered || !tidstats)468 if (!family_registered || !tidstats)
470 return;469 return;
471 470
472 spin_lock_irqsave(&tsk->signal->stats_lock, flags);
473 is_thread_group = tsk->signal->stats ? 1 : 0;
474 spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
475
476 rc = 0;471 rc = 0;
477 /*472 /*
478 * Size includes space for nested attributes473 * Size includes space for nested attributes
@@ -480,6 +475,7 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats, · 1 unmodified line
480 size = nla_total_size(sizeof(u32)) +475 size = nla_total_size(sizeof(u32)) +
481 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);476 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
482 477
478 is_thread_group = (tsk->signal->stats != NULL);
483 if (is_thread_group)479 if (is_thread_group)
484 size = 2 * size; /* PID + STATS + TGID + STATS */480 size = 2 * size; /* PID + STATS + TGID + STATS */
485 481