History

[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

Unified · Split

4 files
  1. include/linux/sched.h +0 −1
  2. include/linux/taskstats_kern.h +6 −9
  3. kernel/fork.c +1 −1
  4. kernel/taskstats.c +6 −10
include/linux/sched.h+0−1
@@ -466,7 +466,6 @@ struct signal_struct { · 465 unmodified lines
466 struct pacct_struct pacct; /* per-process accounting information */466 struct pacct_struct pacct; /* per-process accounting information */
467#endif467#endif
468#ifdef CONFIG_TASKSTATS468#ifdef CONFIG_TASKSTATS
469 spinlock_t stats_lock;
470 struct taskstats *stats;469 struct taskstats *stats;
471#endif470#endif
472};471};
include/linux/taskstats_kern.h+6−9
@@ -23,28 +23,26 @@ static inline void taskstats_exit_free(struct taskstats *tidstats) · 22 unmodified lines
23 23
24static inline void taskstats_tgid_init(struct signal_struct *sig)24static inline void taskstats_tgid_init(struct signal_struct *sig)
25{25{
26 spin_lock_init(&sig->stats_lock);
27 sig->stats = NULL;26 sig->stats = NULL;
28}27}
29 28
30static inline void taskstats_tgid_alloc(struct signal_struct *sig)29static inline void taskstats_tgid_alloc(struct task_struct *tsk)
31{30{
31 struct signal_struct *sig = tsk->signal;
32 struct taskstats *stats;32 struct taskstats *stats;
33 unsigned long flags;
34 33
35 if (sig->stats != NULL)34 if (sig->stats != NULL)
36 return;35 return;
37 36
37 /* No problem if kmem_cache_zalloc() fails */
38 stats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);38 stats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
39 if (!stats)
40 return;
41 39
42 spin_lock_irqsave(&sig->stats_lock, flags);40 spin_lock_irq(&tsk->sighand->siglock);
43 if (!sig->stats) {41 if (!sig->stats) {
44 sig->stats = stats;42 sig->stats = stats;
45 stats = NULL;43 stats = NULL;
46 }44 }
47 spin_unlock_irqrestore(&sig->stats_lock, flags);45 spin_unlock_irq(&tsk->sighand->siglock);
48 46
49 if (stats)47 if (stats)
50 kmem_cache_free(taskstats_cache, stats);48 kmem_cache_free(taskstats_cache, stats);
@@ -59,7 +57,6 @@ static inline void taskstats_tgid_free(struct signal_struct *sig) · 8 unmodified lines
59extern void taskstats_exit_alloc(struct taskstats **, unsigned int *);57extern void taskstats_exit_alloc(struct taskstats **, unsigned int *);
60extern void taskstats_exit_send(struct task_struct *, struct taskstats *, int, unsigned int);58extern void taskstats_exit_send(struct task_struct *, struct taskstats *, int, unsigned int);
61extern void taskstats_init_early(void);59extern void taskstats_init_early(void);
62extern void taskstats_tgid_alloc(struct signal_struct *);
63#else60#else
64static inline void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)61static inline void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
65{}62{}
@@ -71,7 +68,7 @@ static inline void taskstats_exit_send(struct task_struct *tsk, · 5 unmodified lines
71{}68{}
72static inline void taskstats_tgid_init(struct signal_struct *sig)69static inline void taskstats_tgid_init(struct signal_struct *sig)
73{}70{}
74static inline void taskstats_tgid_alloc(struct signal_struct *sig)71static inline void taskstats_tgid_alloc(struct task_struct *tsk)
75{}72{}
76static inline void taskstats_tgid_free(struct signal_struct *sig)73static inline void taskstats_tgid_free(struct signal_struct *sig)
77{}74{}
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