Mercurial > hg > nginx
view src/core/ngx_slab.c @ 9300:5be23505292b
SSI: fixed incorrect or duplicate stub output.
Following 3518:eb3aaf8bd2a9 (0.8.37), r->request_output is only set
if there are data in the first buffer sent in the subrequest. As a
result, following the change mentioned this flag cannot be used to
prevent duplicate ngx_http_ssi_stub_output() calls, since it is not
set if there was already some output, but the first buffer was empty.
Still, when there are multiple subrequests, even an empty subrequest
response might be delayed by the postpone filter, leading to a second
call of ngx_http_ssi_stub_output() during finalization from
ngx_http_writer() the subreqest buffers are released by the postpone
filter. Since r->request_output is not set after the first call, this
resulted in duplicate stub output.
Additionally, checking only the first buffer might be wrong in some
unusual cases. For example, the first buffer might be empty if
$r->flush() is called before printing any data in the embedded Perl
module.
Depending on the postpone_output value and corresponding sizes, this
issue can result in either duplicate or unexpected stub output, or
"zero size buf in writer" alerts.
Following 8124:f5515e727656 (1.23.4), it became slightly easier to
reproduce the issue, as empty static files and empty cache items now
result in a response with an empty buffer. Before the change, an empty
proxied response can be used to reproduce the issue.
Fix is check all buffers and set r->request_output if any non-empty
buffers are sent. This ensures that all unusual cases of non-empty
responses are covered, and also that r->request_output will be set
after the first stub output, preventing duplicate output.
Reported by Jan Gassen.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 04 Jul 2024 17:41:28 +0300 |
parents | d97d09ef3afe |
children |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #define NGX_SLAB_PAGE_MASK 3 #define NGX_SLAB_PAGE 0 #define NGX_SLAB_BIG 1 #define NGX_SLAB_EXACT 2 #define NGX_SLAB_SMALL 3 #if (NGX_PTR_SIZE == 4) #define NGX_SLAB_PAGE_FREE 0 #define NGX_SLAB_PAGE_BUSY 0xffffffff #define NGX_SLAB_PAGE_START 0x80000000 #define NGX_SLAB_SHIFT_MASK 0x0000000f #define NGX_SLAB_MAP_MASK 0xffff0000 #define NGX_SLAB_MAP_SHIFT 16 #define NGX_SLAB_BUSY 0xffffffff #else /* (NGX_PTR_SIZE == 8) */ #define NGX_SLAB_PAGE_FREE 0 #define NGX_SLAB_PAGE_BUSY 0xffffffffffffffff #define NGX_SLAB_PAGE_START 0x8000000000000000 #define NGX_SLAB_SHIFT_MASK 0x000000000000000f #define NGX_SLAB_MAP_MASK 0xffffffff00000000 #define NGX_SLAB_MAP_SHIFT 32 #define NGX_SLAB_BUSY 0xffffffffffffffff #endif #define ngx_slab_slots(pool) \ (ngx_slab_page_t *) ((u_char *) (pool) + sizeof(ngx_slab_pool_t)) #define ngx_slab_page_type(page) ((page)->prev & NGX_SLAB_PAGE_MASK) #define ngx_slab_page_prev(page) \ (ngx_slab_page_t *) ((page)->prev & ~NGX_SLAB_PAGE_MASK) #define ngx_slab_page_addr(pool, page) \ ((((page) - (pool)->pages) << ngx_pagesize_shift) \ + (uintptr_t) (pool)->start) #if (NGX_DEBUG_MALLOC) #define ngx_slab_junk(p, size) ngx_memset(p, 0xA5, size) #elif (NGX_HAVE_DEBUG_MALLOC) #define ngx_slab_junk(p, size) \ if (ngx_debug_malloc) ngx_memset(p, 0xA5, size) #else #define ngx_slab_junk(p, size) #endif static ngx_slab_page_t *ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages); static void ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page, ngx_uint_t pages); static void ngx_slab_error(ngx_slab_pool_t *pool, ngx_uint_t level, char *text); static ngx_uint_t ngx_slab_max_size; static ngx_uint_t ngx_slab_exact_size; static ngx_uint_t ngx_slab_exact_shift; void ngx_slab_sizes_init(void) { ngx_uint_t n; ngx_slab_max_size = ngx_pagesize / 2; ngx_slab_exact_size = ngx_pagesize / (8 * sizeof(uintptr_t)); for (n = ngx_slab_exact_size; n >>= 1; ngx_slab_exact_shift++) { /* void */ } } void ngx_slab_init(ngx_slab_pool_t *pool) { u_char *p; size_t size; ngx_int_t m; ngx_uint_t i, n, pages; ngx_slab_page_t *slots, *page; pool->min_size = (size_t) 1 << pool->min_shift; slots = ngx_slab_slots(pool); p = (u_char *) slots; size = pool->end - p; ngx_slab_junk(p, size); n = ngx_pagesize_shift - pool->min_shift; for (i = 0; i < n; i++) { /* only "next" is used in list head */ slots[i].slab = 0; slots[i].next = &slots[i]; slots[i].prev = 0; } p += n * sizeof(ngx_slab_page_t); pool->stats = (ngx_slab_stat_t *) p; ngx_memzero(pool->stats, n * sizeof(ngx_slab_stat_t)); p += n * sizeof(ngx_slab_stat_t); size -= n * (sizeof(ngx_slab_page_t) + sizeof(ngx_slab_stat_t)); pages = (ngx_uint_t) (size / (ngx_pagesize + sizeof(ngx_slab_page_t))); pool->pages = (ngx_slab_page_t *) p; ngx_memzero(pool->pages, pages * sizeof(ngx_slab_page_t)); page = pool->pages; /* only "next" is used in list head */ pool->free.slab = 0; pool->free.next = page; pool->free.prev = 0; page->slab = pages; page->next = &pool->free; page->prev = (uintptr_t) &pool->free; pool->start = ngx_align_ptr(p + pages * sizeof(ngx_slab_page_t), ngx_pagesize); m = pages - (pool->end - pool->start) / ngx_pagesize; if (m > 0) { pages -= m; page->slab = pages; } pool->last = pool->pages + pages; pool->pfree = pages; pool->log_nomem = 1; pool->log_ctx = &pool->zero; pool->zero = '\0'; } void * ngx_slab_alloc(ngx_slab_pool_t *pool, size_t size) { void *p; ngx_shmtx_lock(&pool->mutex); p = ngx_slab_alloc_locked(pool, size); ngx_shmtx_unlock(&pool->mutex); return p; } void * ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size) { size_t s; uintptr_t p, m, mask, *bitmap; ngx_uint_t i, n, slot, shift, map; ngx_slab_page_t *page, *prev, *slots; if (size > ngx_slab_max_size) { ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %uz", size); page = ngx_slab_alloc_pages(pool, (size >> ngx_pagesize_shift) + ((size % ngx_pagesize) ? 1 : 0)); if (page) { p = ngx_slab_page_addr(pool, page); } else { p = 0; } goto done; } if (size > pool->min_size) { shift = 1; for (s = size - 1; s >>= 1; shift++) { /* void */ } slot = shift - pool->min_shift; } else { shift = pool->min_shift; slot = 0; } pool->stats[slot].reqs++; ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %uz slot: %ui", size, slot); slots = ngx_slab_slots(pool); page = slots[slot].next; if (page->next != page) { if (shift < ngx_slab_exact_shift) { bitmap = (uintptr_t *) ngx_slab_page_addr(pool, page); map = (ngx_pagesize >> shift) / (8 * sizeof(uintptr_t)); for (n = 0; n < map; n++) { if (bitmap[n] != NGX_SLAB_BUSY) { for (m = 1, i = 0; m; m <<= 1, i++) { if (bitmap[n] & m) { continue; } bitmap[n] |= m; i = (n * 8 * sizeof(uintptr_t) + i) << shift; p = (uintptr_t) bitmap + i; pool->stats[slot].used++; if (bitmap[n] == NGX_SLAB_BUSY) { for (n = n + 1; n < map; n++) { if (bitmap[n] != NGX_SLAB_BUSY) { goto done; } } prev = ngx_slab_page_prev(page); prev->next = page->next; page->next->prev = page->prev; page->next = NULL; page->prev = NGX_SLAB_SMALL; } goto done; } } } } else if (shift == ngx_slab_exact_shift) { for (m = 1, i = 0; m; m <<= 1, i++) { if (page->slab & m) { continue; } page->slab |= m; if (page->slab == NGX_SLAB_BUSY) { prev = ngx_slab_page_prev(page); prev->next = page->next; page->next->prev = page->prev; page->next = NULL; page->prev = NGX_SLAB_EXACT; } p = ngx_slab_page_addr(pool, page) + (i << shift); pool->stats[slot].used++; goto done; } } else { /* shift > ngx_slab_exact_shift */ mask = ((uintptr_t) 1 << (ngx_pagesize >> shift)) - 1; mask <<= NGX_SLAB_MAP_SHIFT; for (m = (uintptr_t) 1 << NGX_SLAB_MAP_SHIFT, i = 0; m & mask; m <<= 1, i++) { if (page->slab & m) { continue; } page->slab |= m; if ((page->slab & NGX_SLAB_MAP_MASK) == mask) { prev = ngx_slab_page_prev(page); prev->next = page->next; page->next->prev = page->prev; page->next = NULL; page->prev = NGX_SLAB_BIG; } p = ngx_slab_page_addr(pool, page) + (i << shift); pool->stats[slot].used++; goto done; } } ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_alloc(): page is busy"); ngx_debug_point(); } page = ngx_slab_alloc_pages(pool, 1); if (page) { if (shift < ngx_slab_exact_shift) { bitmap = (uintptr_t *) ngx_slab_page_addr(pool, page); n = (ngx_pagesize >> shift) / ((1 << shift) * 8); if (n == 0) { n = 1; } /* "n" elements for bitmap, plus one requested */ for (i = 0; i < (n + 1) / (8 * sizeof(uintptr_t)); i++) { bitmap[i] = NGX_SLAB_BUSY; } m = ((uintptr_t) 1 << ((n + 1) % (8 * sizeof(uintptr_t)))) - 1; bitmap[i] = m; map = (ngx_pagesize >> shift) / (8 * sizeof(uintptr_t)); for (i = i + 1; i < map; i++) { bitmap[i] = 0; } page->slab = shift; page->next = &slots[slot]; page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL; slots[slot].next = page; pool->stats[slot].total += (ngx_pagesize >> shift) - n; p = ngx_slab_page_addr(pool, page) + (n << shift); pool->stats[slot].used++; goto done; } else if (shift == ngx_slab_exact_shift) { page->slab = 1; page->next = &slots[slot]; page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT; slots[slot].next = page; pool->stats[slot].total += 8 * sizeof(uintptr_t); p = ngx_slab_page_addr(pool, page); pool->stats[slot].used++; goto done; } else { /* shift > ngx_slab_exact_shift */ page->slab = ((uintptr_t) 1 << NGX_SLAB_MAP_SHIFT) | shift; page->next = &slots[slot]; page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG; slots[slot].next = page; pool->stats[slot].total += ngx_pagesize >> shift; p = ngx_slab_page_addr(pool, page); pool->stats[slot].used++; goto done; } } p = 0; pool->stats[slot].fails++; done: ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %p", (void *) p); return (void *) p; } void * ngx_slab_calloc(ngx_slab_pool_t *pool, size_t size) { void *p; ngx_shmtx_lock(&pool->mutex); p = ngx_slab_calloc_locked(pool, size); ngx_shmtx_unlock(&pool->mutex); return p; } void * ngx_slab_calloc_locked(ngx_slab_pool_t *pool, size_t size) { void *p; p = ngx_slab_alloc_locked(pool, size); if (p) { ngx_memzero(p, size); } return p; } void ngx_slab_free(ngx_slab_pool_t *pool, void *p) { ngx_shmtx_lock(&pool->mutex); ngx_slab_free_locked(pool, p); ngx_shmtx_unlock(&pool->mutex); } void ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p) { size_t size; uintptr_t slab, m, *bitmap; ngx_uint_t i, n, type, slot, shift, map; ngx_slab_page_t *slots, *page; ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab free: %p", p); if ((u_char *) p < pool->start || (u_char *) p > pool->end) { ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_free(): outside of pool"); goto fail; } n = ((u_char *) p - pool->start) >> ngx_pagesize_shift; page = &pool->pages[n]; slab = page->slab; type = ngx_slab_page_type(page); switch (type) { case NGX_SLAB_SMALL: shift = slab & NGX_SLAB_SHIFT_MASK; size = (size_t) 1 << shift; if ((uintptr_t) p & (size - 1)) { goto wrong_chunk; } n = ((uintptr_t) p & (ngx_pagesize - 1)) >> shift; m = (uintptr_t) 1 << (n % (8 * sizeof(uintptr_t))); n /= 8 * sizeof(uintptr_t); bitmap = (uintptr_t *) ((uintptr_t) p & ~((uintptr_t) ngx_pagesize - 1)); if (bitmap[n] & m) { slot = shift - pool->min_shift; if (page->next == NULL) { slots = ngx_slab_slots(pool); page->next = slots[slot].next; slots[slot].next = page; page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL; page->next->prev = (uintptr_t) page | NGX_SLAB_SMALL; } bitmap[n] &= ~m; n = (ngx_pagesize >> shift) / ((1 << shift) * 8); if (n == 0) { n = 1; } i = n / (8 * sizeof(uintptr_t)); m = ((uintptr_t) 1 << (n % (8 * sizeof(uintptr_t)))) - 1; if (bitmap[i] & ~m) { goto done; } map = (ngx_pagesize >> shift) / (8 * sizeof(uintptr_t)); for (i = i + 1; i < map; i++) { if (bitmap[i]) { goto done; } } ngx_slab_free_pages(pool, page, 1); pool->stats[slot].total -= (ngx_pagesize >> shift) - n; goto done; } goto chunk_already_free; case NGX_SLAB_EXACT: m = (uintptr_t) 1 << (((uintptr_t) p & (ngx_pagesize - 1)) >> ngx_slab_exact_shift); size = ngx_slab_exact_size; if ((uintptr_t) p & (size - 1)) { goto wrong_chunk; } if (slab & m) { slot = ngx_slab_exact_shift - pool->min_shift; if (slab == NGX_SLAB_BUSY) { slots = ngx_slab_slots(pool); page->next = slots[slot].next; slots[slot].next = page; page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT; page->next->prev = (uintptr_t) page | NGX_SLAB_EXACT; } page->slab &= ~m; if (page->slab) { goto done; } ngx_slab_free_pages(pool, page, 1); pool->stats[slot].total -= 8 * sizeof(uintptr_t); goto done; } goto chunk_already_free; case NGX_SLAB_BIG: shift = slab & NGX_SLAB_SHIFT_MASK; size = (size_t) 1 << shift; if ((uintptr_t) p & (size - 1)) { goto wrong_chunk; } m = (uintptr_t) 1 << ((((uintptr_t) p & (ngx_pagesize - 1)) >> shift) + NGX_SLAB_MAP_SHIFT); if (slab & m) { slot = shift - pool->min_shift; if (page->next == NULL) { slots = ngx_slab_slots(pool); page->next = slots[slot].next; slots[slot].next = page; page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG; page->next->prev = (uintptr_t) page | NGX_SLAB_BIG; } page->slab &= ~m; if (page->slab & NGX_SLAB_MAP_MASK) { goto done; } ngx_slab_free_pages(pool, page, 1); pool->stats[slot].total -= ngx_pagesize >> shift; goto done; } goto chunk_already_free; case NGX_SLAB_PAGE: if ((uintptr_t) p & (ngx_pagesize - 1)) { goto wrong_chunk; } if (!(slab & NGX_SLAB_PAGE_START)) { ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_free(): page is already free"); goto fail; } if (slab == NGX_SLAB_PAGE_BUSY) { ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_free(): pointer to wrong page"); goto fail; } size = slab & ~NGX_SLAB_PAGE_START; ngx_slab_free_pages(pool, page, size); ngx_slab_junk(p, size << ngx_pagesize_shift); return; } /* not reached */ return; done: pool->stats[slot].used--; ngx_slab_junk(p, size); return; wrong_chunk: ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_free(): pointer to wrong chunk"); goto fail; chunk_already_free: ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_free(): chunk is already free"); fail: return; } static ngx_slab_page_t * ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages) { ngx_slab_page_t *page, *p; for (page = pool->free.next; page != &pool->free; page = page->next) { if (page->slab >= pages) { if (page->slab > pages) { page[page->slab - 1].prev = (uintptr_t) &page[pages]; page[pages].slab = page->slab - pages; page[pages].next = page->next; page[pages].prev = page->prev; p = (ngx_slab_page_t *) page->prev; p->next = &page[pages]; page->next->prev = (uintptr_t) &page[pages]; } else { p = (ngx_slab_page_t *) page->prev; p->next = page->next; page->next->prev = page->prev; } page->slab = pages | NGX_SLAB_PAGE_START; page->next = NULL; page->prev = NGX_SLAB_PAGE; pool->pfree -= pages; if (--pages == 0) { return page; } for (p = page + 1; pages; pages--) { p->slab = NGX_SLAB_PAGE_BUSY; p->next = NULL; p->prev = NGX_SLAB_PAGE; p++; } return page; } } if (pool->log_nomem) { ngx_slab_error(pool, NGX_LOG_CRIT, "ngx_slab_alloc() failed: no memory"); } return NULL; } static void ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page, ngx_uint_t pages) { ngx_slab_page_t *prev, *join; pool->pfree += pages; page->slab = pages--; if (pages) { ngx_memzero(&page[1], pages * sizeof(ngx_slab_page_t)); } if (page->next) { prev = ngx_slab_page_prev(page); prev->next = page->next; page->next->prev = page->prev; } join = page + page->slab; if (join < pool->last) { if (ngx_slab_page_type(join) == NGX_SLAB_PAGE) { if (join->next != NULL) { pages += join->slab; page->slab += join->slab; prev = ngx_slab_page_prev(join); prev->next = join->next; join->next->prev = join->prev; join->slab = NGX_SLAB_PAGE_FREE; join->next = NULL; join->prev = NGX_SLAB_PAGE; } } } if (page > pool->pages) { join = page - 1; if (ngx_slab_page_type(join) == NGX_SLAB_PAGE) { if (join->slab == NGX_SLAB_PAGE_FREE) { join = ngx_slab_page_prev(join); } if (join->next != NULL) { pages += join->slab; join->slab += page->slab; prev = ngx_slab_page_prev(join); prev->next = join->next; join->next->prev = join->prev; page->slab = NGX_SLAB_PAGE_FREE; page->next = NULL; page->prev = NGX_SLAB_PAGE; page = join; } } } if (pages) { page[pages].prev = (uintptr_t) page; } page->prev = (uintptr_t) &pool->free; page->next = pool->free.next; page->next->prev = (uintptr_t) page; pool->free.next = page; } static void ngx_slab_error(ngx_slab_pool_t *pool, ngx_uint_t level, char *text) { ngx_log_error(level, ngx_cycle->log, 0, "%s%s", text, pool->log_ctx); }