Mercurial > hg > nginx
view src/core/ngx_buf.c @ 6422:768e287a6f36
Fixed sendfile in threads (or with aio preload) and subrequests.
If sendfile in threads is used, it is possible that multiple
subrequests will trigger multiple ngx_linux_sendfile_thread() calls,
as operations are only serialized in output chain based on r->aio,
that is, on subrequest level.
This resulted in "task #N already active" alerts, in particular, when
running proxy_store.t with "aio threads; sendfile on;".
Fix is to tolerate duplicate calls, with an additional safety check
that the file is the same as previously used.
The same problem also affects "aio on; sendfile on;" on FreeBSD
(previously known as "aio sendfile;"), where aio->preload_handler()
could be called multiple times due to similar reasons, resulting in
"second aio post" alerts. Fix is the same as well.
It is also believed that similar problems can arise if a filter
calls the next body filter multiple times for some reason. These are
mostly theoretical though.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 03 Mar 2016 21:14:12 +0300 |
parents | ac3f78219f85 |
children | 40c2f3e06d23 a3e6d660b179 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> ngx_buf_t * ngx_create_temp_buf(ngx_pool_t *pool, size_t size) { ngx_buf_t *b; b = ngx_calloc_buf(pool); if (b == NULL) { return NULL; } b->start = ngx_palloc(pool, size); if (b->start == NULL) { return NULL; } /* * set by ngx_calloc_buf(): * * b->file_pos = 0; * b->file_last = 0; * b->file = NULL; * b->shadow = NULL; * b->tag = 0; * and flags */ b->pos = b->start; b->last = b->start; b->end = b->last + size; b->temporary = 1; return b; } ngx_chain_t * ngx_alloc_chain_link(ngx_pool_t *pool) { ngx_chain_t *cl; cl = pool->chain; if (cl) { pool->chain = cl->next; return cl; } cl = ngx_palloc(pool, sizeof(ngx_chain_t)); if (cl == NULL) { return NULL; } return cl; } ngx_chain_t * ngx_create_chain_of_bufs(ngx_pool_t *pool, ngx_bufs_t *bufs) { u_char *p; ngx_int_t i; ngx_buf_t *b; ngx_chain_t *chain, *cl, **ll; p = ngx_palloc(pool, bufs->num * bufs->size); if (p == NULL) { return NULL; } ll = &chain; for (i = 0; i < bufs->num; i++) { b = ngx_calloc_buf(pool); if (b == NULL) { return NULL; } /* * set by ngx_calloc_buf(): * * b->file_pos = 0; * b->file_last = 0; * b->file = NULL; * b->shadow = NULL; * b->tag = 0; * and flags * */ b->pos = p; b->last = p; b->temporary = 1; b->start = p; p += bufs->size; b->end = p; cl = ngx_alloc_chain_link(pool); if (cl == NULL) { return NULL; } cl->buf = b; *ll = cl; ll = &cl->next; } *ll = NULL; return chain; } ngx_int_t ngx_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain, ngx_chain_t *in) { ngx_chain_t *cl, **ll; ll = chain; for (cl = *chain; cl; cl = cl->next) { ll = &cl->next; } while (in) { cl = ngx_alloc_chain_link(pool); if (cl == NULL) { return NGX_ERROR; } cl->buf = in->buf; *ll = cl; ll = &cl->next; in = in->next; } *ll = NULL; return NGX_OK; } ngx_chain_t * ngx_chain_get_free_buf(ngx_pool_t *p, ngx_chain_t **free) { ngx_chain_t *cl; if (*free) { cl = *free; *free = cl->next; cl->next = NULL; return cl; } cl = ngx_alloc_chain_link(p); if (cl == NULL) { return NULL; } cl->buf = ngx_calloc_buf(p); if (cl->buf == NULL) { return NULL; } cl->next = NULL; return cl; } void ngx_chain_update_chains(ngx_pool_t *p, ngx_chain_t **free, ngx_chain_t **busy, ngx_chain_t **out, ngx_buf_tag_t tag) { ngx_chain_t *cl; if (*busy == NULL) { *busy = *out; } else { for (cl = *busy; cl->next; cl = cl->next) { /* void */ } cl->next = *out; } *out = NULL; while (*busy) { cl = *busy; if (ngx_buf_size(cl->buf) != 0) { break; } if (cl->buf->tag != tag) { *busy = cl->next; ngx_free_chain(p, cl); continue; } cl->buf->pos = cl->buf->start; cl->buf->last = cl->buf->start; *busy = cl->next; cl->next = *free; *free = cl; } } off_t ngx_chain_coalesce_file(ngx_chain_t **in, off_t limit) { off_t total, size, aligned, fprev; ngx_fd_t fd; ngx_chain_t *cl; total = 0; cl = *in; fd = cl->buf->file->fd; do { size = cl->buf->file_last - cl->buf->file_pos; if (size > limit - total) { size = limit - total; aligned = (cl->buf->file_pos + size + ngx_pagesize - 1) & ~((off_t) ngx_pagesize - 1); if (aligned <= cl->buf->file_last) { size = aligned - cl->buf->file_pos; } } total += size; fprev = cl->buf->file_pos + size; cl = cl->next; } while (cl && cl->buf->in_file && total < limit && fd == cl->buf->file->fd && fprev == cl->buf->file_pos); *in = cl; return total; } ngx_chain_t * ngx_chain_update_sent(ngx_chain_t *in, off_t sent) { off_t size; for ( /* void */ ; in; in = in->next) { if (ngx_buf_special(in->buf)) { continue; } if (sent == 0) { break; } size = ngx_buf_size(in->buf); if (sent >= size) { sent -= size; if (ngx_buf_in_memory(in->buf)) { in->buf->pos = in->buf->last; } if (in->buf->in_file) { in->buf->file_pos = in->buf->file_last; } continue; } if (ngx_buf_in_memory(in->buf)) { in->buf->pos += (size_t) sent; } if (in->buf->in_file) { in->buf->file_pos += sent; } break; } return in; }