Mercurial > hg > nginx
view src/event/ngx_event_accept.c @ 3755:76e3a93821b1
fix race condition if during reconfiguration two cache managers try
to delete old inactive entries: one of them removes a entry just locked by
other manager from the queue and the rbtree as long inactive entry,
causes the latter manager to segfault leaving cache mutex locked,
the bug has been introduced in r3727
author | Igor Sysoev <igor@sysoev.ru> |
---|---|
date | Thu, 02 Sep 2010 14:31:47 +0000 |
parents | 00d436dbf826 |
children | 8a8eb335313d |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> static ngx_int_t ngx_enable_accept_events(ngx_cycle_t *cycle); static ngx_int_t ngx_disable_accept_events(ngx_cycle_t *cycle); static void ngx_close_accepted_connection(ngx_connection_t *c); void ngx_event_accept(ngx_event_t *ev) { socklen_t socklen; ngx_err_t err; ngx_log_t *log; ngx_socket_t s; ngx_event_t *rev, *wev; ngx_listening_t *ls; ngx_connection_t *c, *lc; ngx_event_conf_t *ecf; u_char sa[NGX_SOCKADDRLEN]; ecf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_event_core_module); if (ngx_event_flags & NGX_USE_RTSIG_EVENT) { ev->available = 1; } else if (!(ngx_event_flags & NGX_USE_KQUEUE_EVENT)) { ev->available = ecf->multi_accept; } lc = ev->data; ls = lc->listening; ev->ready = 0; ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "accept on %V, ready: %d", &ls->addr_text, ev->available); do { socklen = NGX_SOCKADDRLEN; s = accept(lc->fd, (struct sockaddr *) sa, &socklen); if (s == -1) { err = ngx_socket_errno; if (err == NGX_EAGAIN) { ngx_log_debug0(NGX_LOG_DEBUG_EVENT, ev->log, err, "accept() not ready"); return; } ngx_log_error((ngx_uint_t) ((err == NGX_ECONNABORTED) ? NGX_LOG_ERR : NGX_LOG_ALERT), ev->log, err, "accept() failed"); if (err == NGX_ECONNABORTED) { if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) { ev->available--; } if (ev->available) { continue; } } return; } #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_accepted, 1); #endif ngx_accept_disabled = ngx_cycle->connection_n / 8 - ngx_cycle->free_connection_n; c = ngx_get_connection(s, ev->log); if (c == NULL) { if (ngx_close_socket(s) == -1) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno, ngx_close_socket_n " failed"); } return; } #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_active, 1); #endif c->pool = ngx_create_pool(ls->pool_size, ev->log); if (c->pool == NULL) { ngx_close_accepted_connection(c); return; } c->sockaddr = ngx_palloc(c->pool, socklen); if (c->sockaddr == NULL) { ngx_close_accepted_connection(c); return; } ngx_memcpy(c->sockaddr, sa, socklen); log = ngx_palloc(c->pool, sizeof(ngx_log_t)); if (log == NULL) { ngx_close_accepted_connection(c); return; } /* set a blocking mode for aio and non-blocking mode for others */ if (ngx_inherited_nonblocking) { if (ngx_event_flags & NGX_USE_AIO_EVENT) { if (ngx_blocking(s) == -1) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno, ngx_blocking_n " failed"); ngx_close_accepted_connection(c); return; } } } else { if (!(ngx_event_flags & (NGX_USE_AIO_EVENT|NGX_USE_RTSIG_EVENT))) { if (ngx_nonblocking(s) == -1) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_socket_errno, ngx_nonblocking_n " failed"); ngx_close_accepted_connection(c); return; } } } *log = ls->log; c->recv = ngx_recv; c->send = ngx_send; c->recv_chain = ngx_recv_chain; c->send_chain = ngx_send_chain; c->log = log; c->pool->log = log; c->socklen = socklen; c->listening = ls; c->local_sockaddr = ls->sockaddr; c->unexpected_eof = 1; #if (NGX_HAVE_UNIX_DOMAIN) if (c->sockaddr->sa_family == AF_UNIX) { c->tcp_nopush = NGX_TCP_NOPUSH_DISABLED; c->tcp_nodelay = NGX_TCP_NODELAY_DISABLED; #if (NGX_SOLARIS) /* Solaris's sendfilev() supports AF_NCA, AF_INET, and AF_INET6 */ c->sendfile = 0; #endif } #endif rev = c->read; wev = c->write; wev->ready = 1; if (ngx_event_flags & (NGX_USE_AIO_EVENT|NGX_USE_RTSIG_EVENT)) { /* rtsig, aio, iocp */ rev->ready = 1; } if (ev->deferred_accept) { rev->ready = 1; #if (NGX_HAVE_KQUEUE) rev->available = 1; #endif } rev->log = log; wev->log = log; /* * TODO: MT: - ngx_atomic_fetch_add() * or protection by critical section or light mutex * * TODO: MP: - allocated in a shared memory * - ngx_atomic_fetch_add() * or protection by critical section or light mutex */ c->number = ngx_atomic_fetch_add(ngx_connection_counter, 1); #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_handled, 1); #endif #if (NGX_THREADS) rev->lock = &c->lock; wev->lock = &c->lock; rev->own_lock = &c->lock; wev->own_lock = &c->lock; #endif if (ls->addr_ntop) { c->addr_text.data = ngx_pnalloc(c->pool, ls->addr_text_max_len); if (c->addr_text.data == NULL) { ngx_close_accepted_connection(c); return; } c->addr_text.len = ngx_sock_ntop(c->sockaddr, c->addr_text.data, ls->addr_text_max_len, 0); if (c->addr_text.len == 0) { ngx_close_accepted_connection(c); return; } } #if (NGX_DEBUG) { in_addr_t i; ngx_event_debug_t *dc; struct sockaddr_in *sin; sin = (struct sockaddr_in *) sa; dc = ecf->debug_connection.elts; for (i = 0; i < ecf->debug_connection.nelts; i++) { if ((sin->sin_addr.s_addr & dc[i].mask) == dc[i].addr) { log->log_level = NGX_LOG_DEBUG_CONNECTION|NGX_LOG_DEBUG_ALL; break; } } } #endif ngx_log_debug3(NGX_LOG_DEBUG_EVENT, log, 0, "*%d accept: %V fd:%d", c->number, &c->addr_text, s); if (ngx_add_conn && (ngx_event_flags & NGX_USE_EPOLL_EVENT) == 0) { if (ngx_add_conn(c) == NGX_ERROR) { ngx_close_accepted_connection(c); return; } } log->data = NULL; log->handler = NULL; ls->handler(c); if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) { ev->available--; } } while (ev->available); } ngx_int_t ngx_trylock_accept_mutex(ngx_cycle_t *cycle) { if (ngx_shmtx_trylock(&ngx_accept_mutex)) { ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "accept mutex locked"); if (ngx_accept_mutex_held && ngx_accept_events == 0 && !(ngx_event_flags & NGX_USE_RTSIG_EVENT)) { return NGX_OK; } if (ngx_enable_accept_events(cycle) == NGX_ERROR) { ngx_shmtx_unlock(&ngx_accept_mutex); return NGX_ERROR; } ngx_accept_events = 0; ngx_accept_mutex_held = 1; return NGX_OK; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "accept mutex lock failed: %ui", ngx_accept_mutex_held); if (ngx_accept_mutex_held) { if (ngx_disable_accept_events(cycle) == NGX_ERROR) { return NGX_ERROR; } ngx_accept_mutex_held = 0; } return NGX_OK; } static ngx_int_t ngx_enable_accept_events(ngx_cycle_t *cycle) { ngx_uint_t i; ngx_listening_t *ls; ngx_connection_t *c; ls = cycle->listening.elts; for (i = 0; i < cycle->listening.nelts; i++) { c = ls[i].connection; if (ngx_event_flags & NGX_USE_RTSIG_EVENT) { if (ngx_add_conn(c) == NGX_ERROR) { return NGX_ERROR; } } else { if (ngx_add_event(c->read, NGX_READ_EVENT, 0) == NGX_ERROR) { return NGX_ERROR; } } } return NGX_OK; } static ngx_int_t ngx_disable_accept_events(ngx_cycle_t *cycle) { ngx_uint_t i; ngx_listening_t *ls; ngx_connection_t *c; ls = cycle->listening.elts; for (i = 0; i < cycle->listening.nelts; i++) { c = ls[i].connection; if (!c->read->active) { continue; } if (ngx_event_flags & NGX_USE_RTSIG_EVENT) { if (ngx_del_conn(c, NGX_DISABLE_EVENT) == NGX_ERROR) { return NGX_ERROR; } } else { if (ngx_del_event(c->read, NGX_READ_EVENT, NGX_DISABLE_EVENT) == NGX_ERROR) { return NGX_ERROR; } } } return NGX_OK; } static void ngx_close_accepted_connection(ngx_connection_t *c) { ngx_socket_t fd; ngx_free_connection(c); fd = c->fd; c->fd = (ngx_socket_t) -1; if (ngx_close_socket(fd) == -1) { ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno, ngx_close_socket_n " failed"); } if (c->pool) { ngx_destroy_pool(c->pool); } #if (NGX_STAT_STUB) (void) ngx_atomic_fetch_add(ngx_stat_active, -1); #endif } u_char * ngx_accept_log_error(ngx_log_t *log, u_char *buf, size_t len) { return ngx_snprintf(buf, len, " while accepting new connection on %V", log->data); }