| 512 | } |
| 513 | |
| 514 | static struct devstat * |
| 515 | devstat_alloc(void) |
| 516 | { |
| 517 | struct devstat *dsp; |
| 518 | struct statspage *spp, *spp2; |
| 519 | u_int u; |
| 520 | static int once; |
| 521 | |
| 522 | mtx_assert(&devstat_mutex, MA_NOTOWNED); |
| 523 | if (!once) { |
| 524 | make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME, |
| 525 | &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0444, |
| 526 | DEVSTAT_DEVICE_NAME); |
| 527 | once = 1; |
| 528 | } |
| 529 | spp2 = NULL; |
| 530 | mtx_lock(&devstat_mutex); |
| 531 | for (;;) { |
| 532 | TAILQ_FOREACH(spp, &pagelist, list) { |
| 533 | if (spp->nfree > 0) |
| 534 | break; |
| 535 | } |
| 536 | if (spp != NULL) |
| 537 | break; |
| 538 | mtx_unlock(&devstat_mutex); |
| 539 | spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK); |
| 540 | spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK); |
| 541 | spp2->nfree = statsperpage; |
| 542 | |
| 543 | /* |
| 544 | * If free statspages were added while the lock was released |
| 545 | * just reuse them. |
| 546 | */ |
| 547 | mtx_lock(&devstat_mutex); |
| 548 | TAILQ_FOREACH(spp, &pagelist, list) |
| 549 | if (spp->nfree > 0) |
| 550 | break; |
| 551 | if (spp == NULL) { |
| 552 | spp = spp2; |
| 553 | |
| 554 | /* |
| 555 | * It would make more sense to add the new page at the |
| 556 | * head but the order on the list determine the |
| 557 | * sequence of the mapping so we can't do that. |
| 558 | */ |
| 559 | TAILQ_INSERT_TAIL(&pagelist, spp, list); |
| 560 | } else |
| 561 | break; |
| 562 | } |
| 563 | dsp = spp->stat; |
| 564 | for (u = 0; u < statsperpage; u++) { |
| 565 | if (dsp->allocated == 0) |
| 566 | break; |
| 567 | dsp++; |
| 568 | } |
| 569 | spp->nfree--; |
| 570 | dsp->allocated = 1; |
| 571 | mtx_unlock(&devstat_mutex); |
no test coverage detected