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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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2
kernel/fork.c
View File

@@ -830,7 +830,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
if (clone_flags & CLONE_THREAD) {
atomic_inc(&current->signal->count);
atomic_inc(&current->signal->live);
taskstats_tgid_alloc(current->signal);
taskstats_tgid_alloc(current);
return 0;
}
sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);

16
kernel/taskstats.c
View File

@@ -241,11 +241,11 @@ static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
tsk = first;
read_lock(&tasklist_lock);
/* Start with stats from dead tasks */
if (first->signal) {
spin_lock_irqsave(&first->signal->stats_lock, flags);
if (first->sighand) {
spin_lock_irqsave(&first->sighand->siglock, flags);
if (first->signal->stats)
memcpy(stats, first->signal->stats, sizeof(*stats));
spin_unlock_irqrestore(&first->signal->stats_lock, flags);
spin_unlock_irqrestore(&first->sighand->siglock, flags);
}
do {
@@ -276,7 +276,7 @@ static void fill_tgid_exit(struct task_struct *tsk)
{
unsigned long flags;
spin_lock_irqsave(&tsk->signal->stats_lock, flags);
spin_lock_irqsave(&tsk->sighand->siglock, flags);
if (!tsk->signal->stats)
goto ret;
@@ -288,7 +288,7 @@ static void fill_tgid_exit(struct task_struct *tsk)
*/
delayacct_add_tsk(tsk->signal->stats, tsk);
ret:
spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
return;
}
@@ -464,15 +464,10 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
size_t size;
int is_thread_group;
struct nlattr *na;
unsigned long flags;
if (!family_registered || !tidstats)
return;
spin_lock_irqsave(&tsk->signal->stats_lock, flags);
is_thread_group = tsk->signal->stats ? 1 : 0;
spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
rc = 0;
/*
* Size includes space for nested attributes
@@ -480,6 +475,7 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
size = nla_total_size(sizeof(u32)) +
nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
is_thread_group = (tsk->signal->stats != NULL);
if (is_thread_group)
size = 2 * size; /* PID + STATS + TGID + STATS */