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authorOleg Nesterov <oleg@tv-sign.ru>2006-10-02 11:18:54 +0200
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-02 16:57:24 +0200
commitb0fa9db6abdb2875a6d3069ddc6a2846a73fa5cd (patch)
tree840fd70ce726f94ff389d97dd012e53ae02f1dcf /fs/proc
parent[PATCH] proc: convert do_task_stat() to use lock_task_sighand() (diff)
downloadlinux-b0fa9db6abdb2875a6d3069ddc6a2846a73fa5cd.tar.xz
linux-b0fa9db6abdb2875a6d3069ddc6a2846a73fa5cd.zip
[PATCH] proc: drop tasklist lock in task_state()
task_state() needs tasklist_lock to protect ->parent/->real_parent. However task->parent points to nowhere only when the actions below happen in order 1) release_task(task) 2) release_task(task->parent) 3) a grace period passed But 3) implies that the memory ops from 1) should be finished, so pid_alive() can't be true in such a case. Otherwise, we don't care if ->parent/->real_parent changes under us. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/array.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 35bd39dac247..25e917fb4739 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -162,7 +162,7 @@ static inline char * task_state(struct task_struct *p, char *buffer)
int g;
struct fdtable *fdt = NULL;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
buffer += sprintf(buffer,
"State:\t%s\n"
"SleepAVG:\t%lu%%\n"
@@ -174,14 +174,13 @@ static inline char * task_state(struct task_struct *p, char *buffer)
"Gid:\t%d\t%d\t%d\t%d\n",
get_task_state(p),
(p->sleep_avg/1024)*100/(1020000000/1024),
- p->tgid,
- p->pid, pid_alive(p) ? p->group_leader->real_parent->tgid : 0,
- pid_alive(p) && p->ptrace ? p->parent->pid : 0,
+ p->tgid, p->pid,
+ pid_alive(p) ? rcu_dereference(p->real_parent)->tgid : 0,
+ pid_alive(p) && p->ptrace ? rcu_dereference(p->parent)->pid : 0,
p->uid, p->euid, p->suid, p->fsuid,
p->gid, p->egid, p->sgid, p->fsgid);
- read_unlock(&tasklist_lock);
+
task_lock(p);
- rcu_read_lock();
if (p->files)
fdt = files_fdtable(p->files);
buffer += sprintf(buffer,