* [linux-next:master 6993/7933] kernel/futex/waitwake.c:422 futex_wait_multiple_setup() warn: bitwise AND condition is false here
@ 2023-08-08 17:11 kernel test robot
0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2023-08-08 17:11 UTC (permalink / raw)
To: oe-kbuild; +Cc: lkp, Dan Carpenter
BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: Peter Zijlstra <peterz@infradead.org>
CC: Jens Axboe <axboe@kernel.dk>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head: 71cd4fc492ec41e4acd85e98bbf7a13753fc1e03
commit: 4a5fb5bbed57575f8e4df73968e6dd4a4fd8c346 [6993/7933] futex: Flag conversion
:::::: branch date: 12 hours ago
:::::: commit date: 23 hours ago
config: riscv-randconfig-m031-20230808 (https://download.01.org/0day-ci/archive/20230809/202308090141.sVrgTsDP-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230809/202308090141.sVrgTsDP-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202308090141.sVrgTsDP-lkp@intel.com/
smatch warnings:
kernel/futex/waitwake.c:422 futex_wait_multiple_setup() warn: bitwise AND condition is false here
vim +422 kernel/futex/waitwake.c
bf69bad38cf63d André Almeida 2021-09-23 382
bf69bad38cf63d André Almeida 2021-09-23 383 /**
bf69bad38cf63d André Almeida 2021-09-23 384 * futex_wait_multiple_setup - Prepare to wait and enqueue multiple futexes
bf69bad38cf63d André Almeida 2021-09-23 385 * @vs: The futex list to wait on
bf69bad38cf63d André Almeida 2021-09-23 386 * @count: The size of the list
bf69bad38cf63d André Almeida 2021-09-23 387 * @woken: Index of the last woken futex, if any. Used to notify the
bf69bad38cf63d André Almeida 2021-09-23 388 * caller that it can return this index to userspace (return parameter)
bf69bad38cf63d André Almeida 2021-09-23 389 *
bf69bad38cf63d André Almeida 2021-09-23 390 * Prepare multiple futexes in a single step and enqueue them. This may fail if
bf69bad38cf63d André Almeida 2021-09-23 391 * the futex list is invalid or if any futex was already awoken. On success the
bf69bad38cf63d André Almeida 2021-09-23 392 * task is ready to interruptible sleep.
bf69bad38cf63d André Almeida 2021-09-23 393 *
bf69bad38cf63d André Almeida 2021-09-23 394 * Return:
bf69bad38cf63d André Almeida 2021-09-23 395 * - 1 - One of the futexes was woken by another thread
bf69bad38cf63d André Almeida 2021-09-23 396 * - 0 - Success
bf69bad38cf63d André Almeida 2021-09-23 397 * - <0 - -EFAULT, -EWOULDBLOCK or -EINVAL
bf69bad38cf63d André Almeida 2021-09-23 398 */
bf69bad38cf63d André Almeida 2021-09-23 399 static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *woken)
bf69bad38cf63d André Almeida 2021-09-23 400 {
bf69bad38cf63d André Almeida 2021-09-23 401 struct futex_hash_bucket *hb;
bf69bad38cf63d André Almeida 2021-09-23 402 bool retry = false;
bf69bad38cf63d André Almeida 2021-09-23 403 int ret, i;
bf69bad38cf63d André Almeida 2021-09-23 404 u32 uval;
bf69bad38cf63d André Almeida 2021-09-23 405
bf69bad38cf63d André Almeida 2021-09-23 406 /*
bf69bad38cf63d André Almeida 2021-09-23 407 * Enqueuing multiple futexes is tricky, because we need to enqueue
bf69bad38cf63d André Almeida 2021-09-23 408 * each futex on the list before dealing with the next one to avoid
bf69bad38cf63d André Almeida 2021-09-23 409 * deadlocking on the hash bucket. But, before enqueuing, we need to
bf69bad38cf63d André Almeida 2021-09-23 410 * make sure that current->state is TASK_INTERRUPTIBLE, so we don't
bf69bad38cf63d André Almeida 2021-09-23 411 * lose any wake events, which cannot be done before the get_futex_key
bf69bad38cf63d André Almeida 2021-09-23 412 * of the next key, because it calls get_user_pages, which can sleep.
bf69bad38cf63d André Almeida 2021-09-23 413 * Thus, we fetch the list of futexes keys in two steps, by first
bf69bad38cf63d André Almeida 2021-09-23 414 * pinning all the memory keys in the futex key, and only then we read
bf69bad38cf63d André Almeida 2021-09-23 415 * each key and queue the corresponding futex.
bf69bad38cf63d André Almeida 2021-09-23 416 *
bf69bad38cf63d André Almeida 2021-09-23 417 * Private futexes doesn't need to recalculate hash in retry, so skip
bf69bad38cf63d André Almeida 2021-09-23 418 * get_futex_key() when retrying.
bf69bad38cf63d André Almeida 2021-09-23 419 */
bf69bad38cf63d André Almeida 2021-09-23 420 retry:
bf69bad38cf63d André Almeida 2021-09-23 421 for (i = 0; i < count; i++) {
4a5fb5bbed5757 Peter Zijlstra 2023-08-07 @422 if (!(vs[i].w.flags & FLAGS_SHARED) && retry)
bf69bad38cf63d André Almeida 2021-09-23 423 continue;
bf69bad38cf63d André Almeida 2021-09-23 424
bf69bad38cf63d André Almeida 2021-09-23 425 ret = get_futex_key(u64_to_user_ptr(vs[i].w.uaddr),
4a5fb5bbed5757 Peter Zijlstra 2023-08-07 426 vs[i].w.flags & FLAGS_SHARED,
bf69bad38cf63d André Almeida 2021-09-23 427 &vs[i].q.key, FUTEX_READ);
bf69bad38cf63d André Almeida 2021-09-23 428
bf69bad38cf63d André Almeida 2021-09-23 429 if (unlikely(ret))
bf69bad38cf63d André Almeida 2021-09-23 430 return ret;
bf69bad38cf63d André Almeida 2021-09-23 431 }
bf69bad38cf63d André Almeida 2021-09-23 432
f5d39b02080914 Peter Zijlstra 2022-08-22 433 set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
bf69bad38cf63d André Almeida 2021-09-23 434
bf69bad38cf63d André Almeida 2021-09-23 435 for (i = 0; i < count; i++) {
bf69bad38cf63d André Almeida 2021-09-23 436 u32 __user *uaddr = (u32 __user *)(unsigned long)vs[i].w.uaddr;
bf69bad38cf63d André Almeida 2021-09-23 437 struct futex_q *q = &vs[i].q;
bf69bad38cf63d André Almeida 2021-09-23 438 u32 val = (u32)vs[i].w.val;
bf69bad38cf63d André Almeida 2021-09-23 439
bf69bad38cf63d André Almeida 2021-09-23 440 hb = futex_q_lock(q);
bf69bad38cf63d André Almeida 2021-09-23 441 ret = futex_get_value_locked(&uval, uaddr);
bf69bad38cf63d André Almeida 2021-09-23 442
bf69bad38cf63d André Almeida 2021-09-23 443 if (!ret && uval == val) {
bf69bad38cf63d André Almeida 2021-09-23 444 /*
bf69bad38cf63d André Almeida 2021-09-23 445 * The bucket lock can't be held while dealing with the
bf69bad38cf63d André Almeida 2021-09-23 446 * next futex. Queue each futex at this moment so hb can
bf69bad38cf63d André Almeida 2021-09-23 447 * be unlocked.
bf69bad38cf63d André Almeida 2021-09-23 448 */
bf69bad38cf63d André Almeida 2021-09-23 449 futex_queue(q, hb);
bf69bad38cf63d André Almeida 2021-09-23 450 continue;
bf69bad38cf63d André Almeida 2021-09-23 451 }
bf69bad38cf63d André Almeida 2021-09-23 452
bf69bad38cf63d André Almeida 2021-09-23 453 futex_q_unlock(hb);
bf69bad38cf63d André Almeida 2021-09-23 454 __set_current_state(TASK_RUNNING);
bf69bad38cf63d André Almeida 2021-09-23 455
bf69bad38cf63d André Almeida 2021-09-23 456 /*
bf69bad38cf63d André Almeida 2021-09-23 457 * Even if something went wrong, if we find out that a futex
bf69bad38cf63d André Almeida 2021-09-23 458 * was woken, we don't return error and return this index to
bf69bad38cf63d André Almeida 2021-09-23 459 * userspace
bf69bad38cf63d André Almeida 2021-09-23 460 */
bf69bad38cf63d André Almeida 2021-09-23 461 *woken = unqueue_multiple(vs, i);
bf69bad38cf63d André Almeida 2021-09-23 462 if (*woken >= 0)
bf69bad38cf63d André Almeida 2021-09-23 463 return 1;
bf69bad38cf63d André Almeida 2021-09-23 464
bf69bad38cf63d André Almeida 2021-09-23 465 if (ret) {
bf69bad38cf63d André Almeida 2021-09-23 466 /*
bf69bad38cf63d André Almeida 2021-09-23 467 * If we need to handle a page fault, we need to do so
bf69bad38cf63d André Almeida 2021-09-23 468 * without any lock and any enqueued futex (otherwise
bf69bad38cf63d André Almeida 2021-09-23 469 * we could lose some wakeup). So we do it here, after
bf69bad38cf63d André Almeida 2021-09-23 470 * undoing all the work done so far. In success, we
bf69bad38cf63d André Almeida 2021-09-23 471 * retry all the work.
bf69bad38cf63d André Almeida 2021-09-23 472 */
bf69bad38cf63d André Almeida 2021-09-23 473 if (get_user(uval, uaddr))
bf69bad38cf63d André Almeida 2021-09-23 474 return -EFAULT;
bf69bad38cf63d André Almeida 2021-09-23 475
bf69bad38cf63d André Almeida 2021-09-23 476 retry = true;
bf69bad38cf63d André Almeida 2021-09-23 477 goto retry;
bf69bad38cf63d André Almeida 2021-09-23 478 }
bf69bad38cf63d André Almeida 2021-09-23 479
bf69bad38cf63d André Almeida 2021-09-23 480 if (uval != val)
bf69bad38cf63d André Almeida 2021-09-23 481 return -EWOULDBLOCK;
bf69bad38cf63d André Almeida 2021-09-23 482 }
bf69bad38cf63d André Almeida 2021-09-23 483
bf69bad38cf63d André Almeida 2021-09-23 484 return 0;
bf69bad38cf63d André Almeida 2021-09-23 485 }
bf69bad38cf63d André Almeida 2021-09-23 486
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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2023-08-08 17:11 [linux-next:master 6993/7933] kernel/futex/waitwake.c:422 futex_wait_multiple_setup() warn: bitwise AND condition is false here kernel test robot
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