diff options
author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-06-26 00:26:01 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-26 09:58:26 -0700 |
commit | a872ff0cb2218dc9688b990c5ccda064dc40946b (patch) | |
tree | ff94ae63e668f0229fc7aeed220def7e9708db3a /fs/proc | |
parent | cc288738c9ae3c64d3c50b86604044d1f6d22941 (diff) |
[PATCH] simplify/fix first_tid()
first_tid:
/* If nr exceeds the number of threads there is nothing todo */
if (nr) {
if (nr >= get_nr_threads(leader))
goto done;
}
This is not reliable: sub-threads can exit after this check, so the
'for' loop below can overlap and proc_task_readdir() can return an
already filldir'ed dirents.
for (; pos && pid_alive(pos); pos = next_thread(pos)) {
if (--nr > 0)
continue;
Off-by-one error, will return 'leader' when nr == 1.
This patch tries to fix these problems and simplify the code.
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/base.c | 38 |
1 files changed, 17 insertions, 21 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 6092a6e2c5a..5ee46d3a5ca 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2227,38 +2227,34 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir) static struct task_struct *first_tid(struct task_struct *leader, int tid, int nr) { - struct task_struct *pos = NULL; + struct task_struct *pos; rcu_read_lock(); /* Attempt to start with the pid of a thread */ if (tid && (nr > 0)) { pos = find_task_by_pid(tid); - if (pos && (pos->group_leader != leader)) - pos = NULL; - if (pos) - nr = 0; + if (pos && (pos->group_leader == leader)) + goto found; } /* If nr exceeds the number of threads there is nothing todo */ - if (nr) { - if (nr >= get_nr_threads(leader)) - goto done; - } + pos = NULL; + if (nr && nr >= get_nr_threads(leader)) + goto out; - /* If we haven't found our starting place yet start with the - * leader and walk nr threads forward. + /* If we haven't found our starting place yet start + * with the leader and walk nr threads forward. */ - if (!pos && (nr >= 0)) - pos = leader; - - for (; pos && pid_alive(pos); pos = next_thread(pos)) { - if (--nr > 0) - continue; - get_task_struct(pos); - goto done; + for (pos = leader; nr > 0; --nr) { + pos = next_thread(pos); + if (pos == leader) { + pos = NULL; + goto out; + } } - pos = NULL; -done: +found: + get_task_struct(pos); +out: rcu_read_unlock(); return pos; } |