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authorOleg Nesterov <oleg@tv-sign.ru>2006-10-28 13:38:53 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-28 14:30:54 -0400
commitb8534d7bd89df0cd41cd47bcd6733a05ea9a691a (patch)
treec4650f417d7f05a9c645d6a0b1f64405ec4c8a39
parent17b02695b254aa2ef0e53df9c8e6548f86e66a9d (diff)
[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(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Shailabh Nagar <nagar@watson.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Jay Lan <jlan@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/linux/sched.h1
-rw-r--r--include/linux/taskstats_kern.h15
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/taskstats.c16
4 files changed, 13 insertions, 21 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6735c1cf334c..eafe4a7b8237 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -466,7 +466,6 @@ struct signal_struct {
466 struct pacct_struct pacct; /* per-process accounting information */ 466 struct pacct_struct pacct; /* per-process accounting information */
467#endif 467#endif
468#ifdef CONFIG_TASKSTATS 468#ifdef CONFIG_TASKSTATS
469 spinlock_t stats_lock;
470 struct taskstats *stats; 469 struct taskstats *stats;
471#endif 470#endif
472}; 471};
diff --git a/include/linux/taskstats_kern.h b/include/linux/taskstats_kern.h
index 664224008fb2..6562a2050a25 100644
--- a/include/linux/taskstats_kern.h
+++ b/include/linux/taskstats_kern.h
@@ -23,28 +23,26 @@ static inline void taskstats_exit_free(struct taskstats *tidstats)
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)
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#else 60#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,
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{}
diff --git a/kernel/fork.c b/kernel/fork.c
index 213326609bac..3da978eec791 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -830,7 +830,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
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);
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 9aeee511a463..b2efda94615a 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -241,11 +241,11 @@ static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
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)
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)
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,
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 attributes 473 * Size includes space for nested attributes
@@ -480,6 +475,7 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
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