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https://github.com/samba-team/samba.git
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b24924d6a6
metze
479 lines
12 KiB
C
479 lines
12 KiB
C
/*
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Unix SMB/CIFS implementation.
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main select loop and event handling - epoll implementation
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Copyright (C) Andrew Tridgell 2003-2005
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Copyright (C) Stefan Metzmacher 2005
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "replace.h"
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#include "system/filesys.h"
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#include "system/select.h"
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#include "tevent.h"
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#include "tevent_internal.h"
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#include "tevent_util.h"
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struct epoll_event_context {
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/* a pointer back to the generic event_context */
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struct tevent_context *ev;
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/* list of filedescriptor events */
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struct tevent_fd *fd_events;
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/* number of registered fd event handlers */
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int num_fd_events;
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/* this is changed by the destructors for the fd event
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type. It is used to detect event destruction by event
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handlers, which means the code that is calling the event
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handler needs to assume that the linked list is no longer
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valid
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*/
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uint32_t destruction_count;
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/* when using epoll this is the handle from epoll_create */
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int epoll_fd;
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pid_t pid;
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};
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/*
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called when a epoll call fails, and we should fallback
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to using select
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*/
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static void epoll_panic(struct epoll_event_context *epoll_ev, const char *reason)
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{
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tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
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"%s (%s) - calling abort()\n", reason, strerror(errno));
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abort();
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}
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/*
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map from TEVENT_FD_* to EPOLLIN/EPOLLOUT
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*/
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static uint32_t epoll_map_flags(uint16_t flags)
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{
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uint32_t ret = 0;
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if (flags & TEVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP);
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if (flags & TEVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP);
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return ret;
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}
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/*
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free the epoll fd
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*/
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static int epoll_ctx_destructor(struct epoll_event_context *epoll_ev)
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{
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close(epoll_ev->epoll_fd);
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epoll_ev->epoll_fd = -1;
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return 0;
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}
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/*
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init the epoll fd
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*/
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static int epoll_init_ctx(struct epoll_event_context *epoll_ev)
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{
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epoll_ev->epoll_fd = epoll_create(64);
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epoll_ev->pid = getpid();
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talloc_set_destructor(epoll_ev, epoll_ctx_destructor);
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if (epoll_ev->epoll_fd == -1) {
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return -1;
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}
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return 0;
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}
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static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde);
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/*
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reopen the epoll handle when our pid changes
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see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an
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demonstration of why this is needed
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*/
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static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
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{
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struct tevent_fd *fde;
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if (epoll_ev->pid == getpid()) {
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return;
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}
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close(epoll_ev->epoll_fd);
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epoll_ev->epoll_fd = epoll_create(64);
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if (epoll_ev->epoll_fd == -1) {
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tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
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"Failed to recreate epoll handle after fork\n");
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return;
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}
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epoll_ev->pid = getpid();
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for (fde=epoll_ev->fd_events;fde;fde=fde->next) {
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epoll_add_event(epoll_ev, fde);
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}
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}
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#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0)
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#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1)
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#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2)
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/*
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add the epoll event to the given fd_event
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*/
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static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
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{
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struct epoll_event event;
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if (epoll_ev->epoll_fd == -1) return;
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fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
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/* if we don't want events yet, don't add an epoll_event */
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if (fde->flags == 0) return;
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ZERO_STRUCT(event);
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event.events = epoll_map_flags(fde->flags);
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event.data.ptr = fde;
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if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) {
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epoll_panic(epoll_ev, "EPOLL_CTL_ADD failed");
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}
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fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
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/* only if we want to read we want to tell the event handler about errors */
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if (fde->flags & TEVENT_FD_READ) {
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fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
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}
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}
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/*
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delete the epoll event for given fd_event
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*/
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static void epoll_del_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
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{
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struct epoll_event event;
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if (epoll_ev->epoll_fd == -1) return;
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fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
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/* if there's no epoll_event, we don't need to delete it */
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if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return;
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ZERO_STRUCT(event);
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event.events = epoll_map_flags(fde->flags);
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event.data.ptr = fde;
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if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event) != 0) {
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tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
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"epoll_del_event failed! probable early close bug (%s)\n",
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strerror(errno));
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}
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fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
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}
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/*
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change the epoll event to the given fd_event
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*/
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static void epoll_mod_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
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{
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struct epoll_event event;
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if (epoll_ev->epoll_fd == -1) return;
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fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
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ZERO_STRUCT(event);
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event.events = epoll_map_flags(fde->flags);
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event.data.ptr = fde;
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if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) {
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epoll_panic(epoll_ev, "EPOLL_CTL_MOD failed");
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}
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/* only if we want to read we want to tell the event handler about errors */
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if (fde->flags & TEVENT_FD_READ) {
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fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
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}
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}
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static void epoll_change_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
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{
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bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
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bool want_read = (fde->flags & TEVENT_FD_READ);
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bool want_write= (fde->flags & TEVENT_FD_WRITE);
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if (epoll_ev->epoll_fd == -1) return;
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fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
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/* there's already an event */
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if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
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if (want_read || (want_write && !got_error)) {
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epoll_mod_event(epoll_ev, fde);
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return;
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}
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/*
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* if we want to match the select behavior, we need to remove the epoll_event
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* when the caller isn't interested in events.
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*
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* this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them
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*/
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epoll_del_event(epoll_ev, fde);
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return;
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}
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/* there's no epoll_event attached to the fde */
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if (want_read || (want_write && !got_error)) {
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epoll_add_event(epoll_ev, fde);
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return;
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}
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}
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/*
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event loop handling using epoll
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*/
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static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval *tvalp)
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{
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int ret, i;
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#define MAXEVENTS 32
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struct epoll_event events[MAXEVENTS];
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uint32_t destruction_count = ++epoll_ev->destruction_count;
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int timeout = -1;
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if (epoll_ev->epoll_fd == -1) return -1;
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if (tvalp) {
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/* it's better to trigger timed events a bit later than to early */
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timeout = ((tvalp->tv_usec+999) / 1000) + (tvalp->tv_sec*1000);
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}
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if (epoll_ev->ev->signal_events &&
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tevent_common_check_signal(epoll_ev->ev)) {
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return 0;
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}
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ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout);
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if (ret == -1 && errno == EINTR && epoll_ev->ev->signal_events) {
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if (tevent_common_check_signal(epoll_ev->ev)) {
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return 0;
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}
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}
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if (ret == -1 && errno != EINTR) {
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epoll_panic(epoll_ev, "epoll_wait() failed");
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return -1;
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}
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if (ret == 0 && tvalp) {
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/* we don't care about a possible delay here */
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tevent_common_loop_timer_delay(epoll_ev->ev);
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return 0;
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}
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for (i=0;i<ret;i++) {
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struct tevent_fd *fde = talloc_get_type(events[i].data.ptr,
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struct tevent_fd);
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uint16_t flags = 0;
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if (fde == NULL) {
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epoll_panic(epoll_ev, "epoll_wait() gave bad data");
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return -1;
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}
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if (events[i].events & (EPOLLHUP|EPOLLERR)) {
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fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
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/*
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* if we only wait for TEVENT_FD_WRITE, we should not tell the
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* event handler about it, and remove the epoll_event,
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* as we only report errors when waiting for read events,
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* to match the select() behavior
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*/
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if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
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epoll_del_event(epoll_ev, fde);
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continue;
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}
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flags |= TEVENT_FD_READ;
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}
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if (events[i].events & EPOLLIN) flags |= TEVENT_FD_READ;
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if (events[i].events & EPOLLOUT) flags |= TEVENT_FD_WRITE;
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if (flags) {
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fde->handler(epoll_ev->ev, fde, flags, fde->private_data);
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if (destruction_count != epoll_ev->destruction_count) {
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break;
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}
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}
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}
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return 0;
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}
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/*
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create a epoll_event_context structure.
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*/
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static int epoll_event_context_init(struct tevent_context *ev)
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{
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int ret;
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struct epoll_event_context *epoll_ev;
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epoll_ev = talloc_zero(ev, struct epoll_event_context);
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if (!epoll_ev) return -1;
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epoll_ev->ev = ev;
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epoll_ev->epoll_fd = -1;
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ret = epoll_init_ctx(epoll_ev);
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if (ret != 0) {
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talloc_free(epoll_ev);
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return ret;
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}
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ev->additional_data = epoll_ev;
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return 0;
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}
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/*
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destroy an fd_event
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*/
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static int epoll_event_fd_destructor(struct tevent_fd *fde)
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{
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struct tevent_context *ev = fde->event_ctx;
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struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
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struct epoll_event_context);
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epoll_check_reopen(epoll_ev);
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epoll_ev->num_fd_events--;
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epoll_ev->destruction_count++;
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DLIST_REMOVE(epoll_ev->fd_events, fde);
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epoll_del_event(epoll_ev, fde);
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if (fde->close_fn) {
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fde->close_fn(ev, fde, fde->fd, fde->private_data);
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fde->fd = -1;
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}
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return 0;
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}
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/*
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add a fd based event
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return NULL on failure (memory allocation error)
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*/
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static struct tevent_fd *epoll_event_add_fd(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
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int fd, uint16_t flags,
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tevent_fd_handler_t handler,
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void *private_data,
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const char *handler_name,
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const char *location)
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{
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struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
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struct epoll_event_context);
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struct tevent_fd *fde;
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epoll_check_reopen(epoll_ev);
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fde = talloc(mem_ctx?mem_ctx:ev, struct tevent_fd);
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if (!fde) return NULL;
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fde->event_ctx = ev;
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fde->fd = fd;
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fde->flags = flags;
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fde->handler = handler;
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fde->close_fn = NULL;
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fde->private_data = private_data;
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fde->handler_name = handler_name;
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fde->location = location;
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fde->additional_flags = 0;
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fde->additional_data = NULL;
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epoll_ev->num_fd_events++;
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talloc_set_destructor(fde, epoll_event_fd_destructor);
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DLIST_ADD(epoll_ev->fd_events, fde);
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epoll_add_event(epoll_ev, fde);
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return fde;
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}
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/*
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set the fd event flags
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*/
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static void epoll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
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{
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struct tevent_context *ev;
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struct epoll_event_context *epoll_ev;
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if (fde->flags == flags) return;
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ev = fde->event_ctx;
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epoll_ev = talloc_get_type(ev->additional_data, struct epoll_event_context);
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fde->flags = flags;
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epoll_check_reopen(epoll_ev);
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epoll_change_event(epoll_ev, fde);
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}
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/*
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do a single event loop using the events defined in ev
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*/
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static int epoll_event_loop_once(struct tevent_context *ev)
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{
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struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
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struct epoll_event_context);
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struct timeval tval;
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tval = tevent_common_loop_timer_delay(ev);
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if (ev_timeval_is_zero(&tval)) {
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return 0;
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}
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epoll_check_reopen(epoll_ev);
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return epoll_event_loop(epoll_ev, &tval);
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}
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/*
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return on failure or (with 0) if all fd events are removed
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*/
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static int epoll_event_loop_wait(struct tevent_context *ev)
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{
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struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
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struct epoll_event_context);
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while (epoll_ev->num_fd_events) {
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if (epoll_event_loop_once(ev) != 0) {
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break;
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}
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}
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return 0;
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}
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static const struct tevent_ops epoll_event_ops = {
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.context_init = epoll_event_context_init,
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.add_fd = epoll_event_add_fd,
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.set_fd_close_fn= tevent_common_fd_set_close_fn,
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.get_fd_flags = tevent_common_fd_get_flags,
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.set_fd_flags = epoll_event_set_fd_flags,
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.add_timer = tevent_common_add_timer,
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.add_signal = tevent_common_add_signal,
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.loop_once = epoll_event_loop_once,
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.loop_wait = epoll_event_loop_wait,
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};
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bool tevent_epoll_init(void)
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{
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return tevent_register_backend("epoll", &epoll_event_ops);
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}
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