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authorOleg Nesterov <oleg@tv-sign.ru>2006-06-26 03:26:01 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 12:58:26 -0400
commita872ff0cb2218dc9688b990c5ccda064dc40946b (patch)
treeff94ae63e668f0229fc7aeed220def7e9708db3a /fs/proc/base.c
parentcc288738c9ae3c64d3c50b86604044d1f6d22941 (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/base.c')
-rw-r--r--fs/proc/base.c38
1 files changed, 17 insertions, 21 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6092a6e2c5a9..5ee46d3a5cac 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)
2227static struct task_struct *first_tid(struct task_struct *leader, 2227static struct task_struct *first_tid(struct task_struct *leader,
2228 int tid, int nr) 2228 int tid, int nr)
2229{ 2229{
2230 struct task_struct *pos = NULL; 2230 struct task_struct *pos;
2231 2231
2232 rcu_read_lock(); 2232 rcu_read_lock();
2233 /* Attempt to start with the pid of a thread */ 2233 /* Attempt to start with the pid of a thread */
2234 if (tid && (nr > 0)) { 2234 if (tid && (nr > 0)) {
2235 pos = find_task_by_pid(tid); 2235 pos = find_task_by_pid(tid);
2236 if (pos && (pos->group_leader != leader)) 2236 if (pos && (pos->group_leader == leader))
2237 pos = NULL; 2237 goto found;
2238 if (pos)
2239 nr = 0;
2240 } 2238 }
2241 2239
2242 /* If nr exceeds the number of threads there is nothing todo */ 2240 /* If nr exceeds the number of threads there is nothing todo */
2243 if (nr) { 2241 pos = NULL;
2244 if (nr >= get_nr_threads(leader)) 2242 if (nr && nr >= get_nr_threads(leader))
2245 goto done; 2243 goto out;
2246 }
2247 2244
2248 /* If we haven't found our starting place yet start with the 2245 /* If we haven't found our starting place yet start
2249 * leader and walk nr threads forward. 2246 * with the leader and walk nr threads forward.
2250 */ 2247 */
2251 if (!pos && (nr >= 0)) 2248 for (pos = leader; nr > 0; --nr) {
2252 pos = leader; 2249 pos = next_thread(pos);
2253 2250 if (pos == leader) {
2254 for (; pos && pid_alive(pos); pos = next_thread(pos)) { 2251 pos = NULL;
2255 if (--nr > 0) 2252 goto out;
2256 continue; 2253 }
2257 get_task_struct(pos);
2258 goto done;
2259 } 2254 }
2260 pos = NULL; 2255found:
2261done: 2256 get_task_struct(pos);
2257out:
2262 rcu_read_unlock(); 2258 rcu_read_unlock();
2263 return pos; 2259 return pos;
2264} 2260}