Mercurial > hg > nginx
view src/os/unix/ngx_channel.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 | 3377f9459e99 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_channel.h> ngx_int_t ngx_write_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log) { ssize_t n; ngx_err_t err; struct iovec iov[1]; struct msghdr msg; #if (NGX_HAVE_MSGHDR_MSG_CONTROL) union { struct cmsghdr cm; char space[CMSG_SPACE(sizeof(int))]; } cmsg; if (ch->fd == -1) { msg.msg_control = NULL; msg.msg_controllen = 0; } else { msg.msg_control = (caddr_t) &cmsg; msg.msg_controllen = sizeof(cmsg); ngx_memzero(&cmsg, sizeof(cmsg)); cmsg.cm.cmsg_len = CMSG_LEN(sizeof(int)); cmsg.cm.cmsg_level = SOL_SOCKET; cmsg.cm.cmsg_type = SCM_RIGHTS; /* * We have to use ngx_memcpy() instead of simple * *(int *) CMSG_DATA(&cmsg.cm) = ch->fd; * because some gcc 4.4 with -O2/3/s optimization issues the warning: * dereferencing type-punned pointer will break strict-aliasing rules * * Fortunately, gcc with -O1 compiles this ngx_memcpy() * in the same simple assignment as in the code above */ ngx_memcpy(CMSG_DATA(&cmsg.cm), &ch->fd, sizeof(int)); } msg.msg_flags = 0; #else if (ch->fd == -1) { msg.msg_accrights = NULL; msg.msg_accrightslen = 0; } else { msg.msg_accrights = (caddr_t) &ch->fd; msg.msg_accrightslen = sizeof(int); } #endif iov[0].iov_base = (char *) ch; iov[0].iov_len = size; msg.msg_name = NULL; msg.msg_namelen = 0; msg.msg_iov = iov; msg.msg_iovlen = 1; n = sendmsg(s, &msg, 0); if (n == -1) { err = ngx_errno; if (err == NGX_EAGAIN) { return NGX_AGAIN; } ngx_log_error(NGX_LOG_ALERT, log, err, "sendmsg() failed"); return NGX_ERROR; } return NGX_OK; } ngx_int_t ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log) { ssize_t n; ngx_err_t err; struct iovec iov[1]; struct msghdr msg; #if (NGX_HAVE_MSGHDR_MSG_CONTROL) union { struct cmsghdr cm; char space[CMSG_SPACE(sizeof(int))]; } cmsg; #else int fd; #endif iov[0].iov_base = (char *) ch; iov[0].iov_len = size; msg.msg_name = NULL; msg.msg_namelen = 0; msg.msg_iov = iov; msg.msg_iovlen = 1; #if (NGX_HAVE_MSGHDR_MSG_CONTROL) msg.msg_control = (caddr_t) &cmsg; msg.msg_controllen = sizeof(cmsg); #else msg.msg_accrights = (caddr_t) &fd; msg.msg_accrightslen = sizeof(int); #endif n = recvmsg(s, &msg, 0); if (n == -1) { err = ngx_errno; if (err == NGX_EAGAIN) { return NGX_AGAIN; } ngx_log_error(NGX_LOG_ALERT, log, err, "recvmsg() failed"); return NGX_ERROR; } if (n == 0) { ngx_log_debug0(NGX_LOG_DEBUG_CORE, log, 0, "recvmsg() returned zero"); return NGX_ERROR; } if ((size_t) n < sizeof(ngx_channel_t)) { ngx_log_error(NGX_LOG_ALERT, log, 0, "recvmsg() returned not enough data: %z", n); return NGX_ERROR; } #if (NGX_HAVE_MSGHDR_MSG_CONTROL) if (ch->command == NGX_CMD_OPEN_CHANNEL) { if (cmsg.cm.cmsg_len < (socklen_t) CMSG_LEN(sizeof(int))) { ngx_log_error(NGX_LOG_ALERT, log, 0, "recvmsg() returned too small ancillary data"); return NGX_ERROR; } if (cmsg.cm.cmsg_level != SOL_SOCKET || cmsg.cm.cmsg_type != SCM_RIGHTS) { ngx_log_error(NGX_LOG_ALERT, log, 0, "recvmsg() returned invalid ancillary data " "level %d or type %d", cmsg.cm.cmsg_level, cmsg.cm.cmsg_type); return NGX_ERROR; } /* ch->fd = *(int *) CMSG_DATA(&cmsg.cm); */ ngx_memcpy(&ch->fd, CMSG_DATA(&cmsg.cm), sizeof(int)); } if (msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) { ngx_log_error(NGX_LOG_ALERT, log, 0, "recvmsg() truncated data"); } #else if (ch->command == NGX_CMD_OPEN_CHANNEL) { if (msg.msg_accrightslen != sizeof(int)) { ngx_log_error(NGX_LOG_ALERT, log, 0, "recvmsg() returned no ancillary data"); return NGX_ERROR; } ch->fd = fd; } #endif return n; } ngx_int_t ngx_add_channel_event(ngx_cycle_t *cycle, ngx_fd_t fd, ngx_int_t event, ngx_event_handler_pt handler) { ngx_event_t *ev, *rev, *wev; ngx_connection_t *c; c = ngx_get_connection(fd, cycle->log); if (c == NULL) { return NGX_ERROR; } c->pool = cycle->pool; rev = c->read; wev = c->write; rev->log = cycle->log; wev->log = cycle->log; rev->channel = 1; wev->channel = 1; ev = (event == NGX_READ_EVENT) ? rev : wev; ev->handler = handler; if (ngx_add_conn && (ngx_event_flags & NGX_USE_EPOLL_EVENT) == 0) { if (ngx_add_conn(c) == NGX_ERROR) { ngx_free_connection(c); return NGX_ERROR; } } else { if (ngx_add_event(ev, event, 0) == NGX_ERROR) { ngx_free_connection(c); return NGX_ERROR; } } return NGX_OK; } void ngx_close_channel(ngx_fd_t *fd, ngx_log_t *log) { if (close(fd[0]) == -1) { ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "close() channel failed"); } if (close(fd[1]) == -1) { ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "close() channel failed"); } }