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

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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>
This commit is contained in:
Oleg Nesterov
2006-10-28 10:38:53 -07:00
committed by Linus Torvalds
parent 17b02695b2
commit b8534d7bd8
4 changed files with 13 additions and 21 deletions
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15
include/linux/taskstats_kern.h
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@ -23,28 +23,26 @@ static inline void taskstats_exit_free(struct taskstats *tidstats)
static inline void taskstats_tgid_init(struct signal_struct *sig)
{
spin_lock_init(&sig->stats_lock);
sig->stats = NULL;
}
static inline void taskstats_tgid_alloc(struct signal_struct *sig)
static inline void taskstats_tgid_alloc(struct task_struct *tsk)
{
struct signal_struct *sig = tsk->signal;
struct taskstats *stats;
unsigned long flags;
if (sig->stats != NULL)
return;
/* No problem if kmem_cache_zalloc() fails */
stats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
if (!stats)
return;
spin_lock_irqsave(&sig->stats_lock, flags);
spin_lock_irq(&tsk->sighand->siglock);
if (!sig->stats) {
sig->stats = stats;
stats = NULL;
}
spin_unlock_irqrestore(&sig->stats_lock, flags);
spin_unlock_irq(&tsk->sighand->siglock);
if (stats)
kmem_cache_free(taskstats_cache, stats);
@ -59,7 +57,6 @@ static inline void taskstats_tgid_free(struct signal_struct *sig)
extern void taskstats_exit_alloc(struct taskstats **, unsigned int *);
extern void taskstats_exit_send(struct task_struct *, struct taskstats *, int, unsigned int);
extern void taskstats_init_early(void);
extern void taskstats_tgid_alloc(struct signal_struct *);
#else
static inline void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
{}
@ -71,7 +68,7 @@ static inline void taskstats_exit_send(struct task_struct *tsk,
{}
static inline void taskstats_tgid_init(struct signal_struct *sig)
{}
static inline void taskstats_tgid_alloc(struct signal_struct *sig)
static inline void taskstats_tgid_alloc(struct task_struct *tsk)
{}
static inline void taskstats_tgid_free(struct signal_struct *sig)
{}