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authorOleg Nesterov <oleg@tv-sign.ru>2006-10-02 05:18:53 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-02 10:57:24 -0400
commita593d6edeb0a5a2c6e6919b225cec668a375df52 (patch)
treef61ea811ad6c9d6bbba9268bdb08cf507fab5e93 /fs/proc/array.c
parent5e6b3f42edc20e988b186fbfb9eec174294222ea (diff)
[PATCH] proc: convert do_task_stat() to use lock_task_sighand()
Drop tasklist_lock. ->siglock protects almost all interesting data (including sub-threads traversal) except: ->signal->tty protected by tty_mutex ->real_parent the task can't be unhashed while we are holding ->siglock, so ->real_parent can change from under us but we can safely dereference it under rcu_read_lock() ->pgrp/->session we can get inconsistent numbers if the task does sys_setsid/daemonize at the same time. I hope this is acceptable. 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/array.c')
-rw-r--r--fs/proc/array.c63
1 files changed, 35 insertions, 28 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 279fbf542c88..35bd39dac247 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -321,7 +321,7 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
321 sigset_t sigign, sigcatch; 321 sigset_t sigign, sigcatch;
322 char state; 322 char state;
323 int res; 323 int res;
324 pid_t ppid, pgid = -1, sid = -1; 324 pid_t ppid = 0, pgid = -1, sid = -1;
325 int num_threads = 0; 325 int num_threads = 0;
326 struct mm_struct *mm; 326 struct mm_struct *mm;
327 unsigned long long start_time; 327 unsigned long long start_time;
@@ -329,8 +329,8 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
329 unsigned long min_flt = 0, maj_flt = 0; 329 unsigned long min_flt = 0, maj_flt = 0;
330 cputime_t cutime, cstime, utime, stime; 330 cputime_t cutime, cstime, utime, stime;
331 unsigned long rsslim = 0; 331 unsigned long rsslim = 0;
332 struct task_struct *t;
333 char tcomm[sizeof(task->comm)]; 332 char tcomm[sizeof(task->comm)];
333 unsigned long flags;
334 334
335 state = *get_task_state(task); 335 state = *get_task_state(task);
336 vsize = eip = esp = 0; 336 vsize = eip = esp = 0;
@@ -348,15 +348,33 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
348 cutime = cstime = utime = stime = cputime_zero; 348 cutime = cstime = utime = stime = cputime_zero;
349 349
350 mutex_lock(&tty_mutex); 350 mutex_lock(&tty_mutex);
351 read_lock(&tasklist_lock); 351 rcu_read_lock();
352 if (task->sighand) { 352 if (lock_task_sighand(task, &flags)) {
353 spin_lock_irq(&task->sighand->siglock); 353 struct signal_struct *sig = task->signal;
354 num_threads = atomic_read(&task->signal->count); 354 struct tty_struct *tty = sig->tty;
355
356 if (tty) {
357 /*
358 * sig->tty is not stable, but tty_mutex
359 * protects us from release_dev(tty)
360 */
361 barrier();
362 tty_pgrp = tty->pgrp;
363 tty_nr = new_encode_dev(tty_devnum(tty));
364 }
365
366 num_threads = atomic_read(&sig->count);
355 collect_sigign_sigcatch(task, &sigign, &sigcatch); 367 collect_sigign_sigcatch(task, &sigign, &sigcatch);
356 368
369 cmin_flt = sig->cmin_flt;
370 cmaj_flt = sig->cmaj_flt;
371 cutime = sig->cutime;
372 cstime = sig->cstime;
373 rsslim = sig->rlim[RLIMIT_RSS].rlim_cur;
374
357 /* add up live thread stats at the group level */ 375 /* add up live thread stats at the group level */
358 if (whole) { 376 if (whole) {
359 t = task; 377 struct task_struct *t = task;
360 do { 378 do {
361 min_flt += t->min_flt; 379 min_flt += t->min_flt;
362 maj_flt += t->maj_flt; 380 maj_flt += t->maj_flt;
@@ -364,31 +382,20 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
364 stime = cputime_add(stime, t->stime); 382 stime = cputime_add(stime, t->stime);
365 t = next_thread(t); 383 t = next_thread(t);
366 } while (t != task); 384 } while (t != task);
367 }
368 385
369 spin_unlock_irq(&task->sighand->siglock); 386 min_flt += sig->min_flt;
370 } 387 maj_flt += sig->maj_flt;
371 if (task->signal) { 388 utime = cputime_add(utime, sig->utime);
372 if (task->signal->tty) { 389 stime = cputime_add(stime, sig->stime);
373 tty_pgrp = task->signal->tty->pgrp;
374 tty_nr = new_encode_dev(tty_devnum(task->signal->tty));
375 } 390 }
391
392 sid = sig->session;
376 pgid = process_group(task); 393 pgid = process_group(task);
377 sid = task->signal->session; 394 ppid = rcu_dereference(task->real_parent)->tgid;
378 cmin_flt = task->signal->cmin_flt; 395
379 cmaj_flt = task->signal->cmaj_flt; 396 unlock_task_sighand(task, &flags);
380 cutime = task->signal->cutime;
381 cstime = task->signal->cstime;
382 rsslim = task->signal->rlim[RLIMIT_RSS].rlim_cur;
383 if (whole) {
384 min_flt += task->signal->min_flt;
385 maj_flt += task->signal->maj_flt;
386 utime = cputime_add(utime, task->signal->utime);
387 stime = cputime_add(stime, task->signal->stime);
388 }
389 } 397 }
390 ppid = pid_alive(task) ? task->group_leader->real_parent->tgid : 0; 398 rcu_read_unlock();
391 read_unlock(&tasklist_lock);
392 mutex_unlock(&tty_mutex); 399 mutex_unlock(&tty_mutex);
393 400
394 if (!whole || num_threads<2) 401 if (!whole || num_threads<2)