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authorEric W. Biederman <ebiederm@xmission.com>2006-06-26 09:26:01 +0200
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 18:58:26 +0200
commitcc288738c9ae3c64d3c50b86604044d1f6d22941 (patch)
tree87058616bfa84572647fbe574fe733e81c1d17b6 /fs/proc/base.c
parent[PATCH] proc: Cleanup proc_fd_access_allowed (diff)
downloadlinux-cc288738c9ae3c64d3c50b86604044d1f6d22941.tar.xz
linux-cc288738c9ae3c64d3c50b86604044d1f6d22941.zip
[PATCH] proc: Remove tasklist_lock from proc_task_readdir.
This is just like my previous removal of tasklist_lock from first_tgid, and next_tgid. It simply had to wait until it was rcu safe to walk the thread list. This should be the last instance of the tasklist_lock in proc. So user processes should not be able to influence the tasklist lock hold times. Signed-off-by: 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/base.c')
-rw-r--r--fs/proc/base.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 773469703c62..6092a6e2c5a9 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2224,11 +2224,12 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
* In the case of a seek we start with the leader and walk nr
* threads past it.
*/
-static struct task_struct *first_tid(struct task_struct *leader, int tid, int nr)
+static struct task_struct *first_tid(struct task_struct *leader,
+ int tid, int nr)
{
struct task_struct *pos = NULL;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
/* Attempt to start with the pid of a thread */
if (tid && (nr > 0)) {
pos = find_task_by_pid(tid);
@@ -2258,7 +2259,7 @@ static struct task_struct *first_tid(struct task_struct *leader, int tid, int nr
}
pos = NULL;
done:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return pos;
}
@@ -2271,7 +2272,7 @@ done:
static struct task_struct *next_tid(struct task_struct *start)
{
struct task_struct *pos;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
pos = start;
if (pid_alive(start))
pos = next_thread(start);
@@ -2279,7 +2280,7 @@ static struct task_struct *next_tid(struct task_struct *start)
get_task_struct(pos);
else
pos = NULL;
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
put_task_struct(start);
return pos;
}