diff options
Diffstat (limited to 'usr.sbin/bhyve/mevent.c')
| -rw-r--r-- | usr.sbin/bhyve/mevent.c | 432 |
1 files changed, 432 insertions, 0 deletions
diff --git a/usr.sbin/bhyve/mevent.c b/usr.sbin/bhyve/mevent.c new file mode 100644 index 0000000..a6109db --- /dev/null +++ b/usr.sbin/bhyve/mevent.c @@ -0,0 +1,432 @@ +/*- + * Copyright (c) 2011 NetApp, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +/* + * Micro event library for FreeBSD, designed for a single i/o thread + * using kqueue, and having events be persistent by default. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <assert.h> +#include <errno.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> + +#include <sys/types.h> +#include <sys/event.h> +#include <sys/time.h> + +#include <pthread.h> +#include <pthread_np.h> + +#include "mevent.h" + +#define MEVENT_MAX 64 + +#define MEV_ENABLE 1 +#define MEV_DISABLE 2 +#define MEV_DEL_PENDING 3 + +extern char *vmname; + +static pthread_t mevent_tid; +static int mevent_pipefd[2]; +static pthread_mutex_t mevent_lmutex = PTHREAD_MUTEX_INITIALIZER; + +struct mevent { + void (*me_func)(int, enum ev_type, void *); + int me_fd; + enum ev_type me_type; + void *me_param; + int me_cq; + int me_state; + int me_closefd; + LIST_ENTRY(mevent) me_list; +}; + +static LIST_HEAD(listhead, mevent) global_head, change_head; + +static void +mevent_qlock(void) +{ + pthread_mutex_lock(&mevent_lmutex); +} + +static void +mevent_qunlock(void) +{ + pthread_mutex_unlock(&mevent_lmutex); +} + +static void +mevent_pipe_read(int fd, enum ev_type type, void *param) +{ + char buf[MEVENT_MAX]; + int status; + + /* + * Drain the pipe read side. The fd is non-blocking so this is + * safe to do. + */ + do { + status = read(fd, buf, sizeof(buf)); + } while (status == MEVENT_MAX); +} + +static void +mevent_notify(void) +{ + char c; + + /* + * If calling from outside the i/o thread, write a byte on the + * pipe to force the i/o thread to exit the blocking kevent call. + */ + if (mevent_pipefd[1] != 0 && pthread_self() != mevent_tid) { + write(mevent_pipefd[1], &c, 1); + } +} + +static int +mevent_kq_filter(struct mevent *mevp) +{ + int retval; + + retval = 0; + + if (mevp->me_type == EVF_READ) + retval = EVFILT_READ; + + if (mevp->me_type == EVF_WRITE) + retval = EVFILT_WRITE; + + return (retval); +} + +static int +mevent_kq_flags(struct mevent *mevp) +{ + int ret; + + switch (mevp->me_state) { + case MEV_ENABLE: + ret = EV_ADD; + break; + case MEV_DISABLE: + ret = EV_DISABLE; + break; + case MEV_DEL_PENDING: + ret = EV_DELETE; + break; + } + + return (ret); +} + +static int +mevent_kq_fflags(struct mevent *mevp) +{ + /* XXX nothing yet, perhaps EV_EOF for reads ? */ + return (0); +} + +static int +mevent_build(int mfd, struct kevent *kev) +{ + struct mevent *mevp, *tmpp; + int i; + + i = 0; + + mevent_qlock(); + + LIST_FOREACH_SAFE(mevp, &change_head, me_list, tmpp) { + if (mevp->me_closefd) { + /* + * A close of the file descriptor will remove the + * event + */ + close(mevp->me_fd); + } else { + kev[i].ident = mevp->me_fd; + kev[i].filter = mevent_kq_filter(mevp); + kev[i].flags = mevent_kq_flags(mevp); + kev[i].fflags = mevent_kq_fflags(mevp); + kev[i].data = 0; + kev[i].udata = mevp; + i++; + } + + mevp->me_cq = 0; + LIST_REMOVE(mevp, me_list); + + if (mevp->me_state == MEV_DEL_PENDING) { + free(mevp); + } else { + LIST_INSERT_HEAD(&global_head, mevp, me_list); + } + + assert(i < MEVENT_MAX); + } + + mevent_qunlock(); + + return (i); +} + +static void +mevent_handle(struct kevent *kev, int numev) +{ + struct mevent *mevp; + int i; + + for (i = 0; i < numev; i++) { + mevp = kev[i].udata; + + /* XXX check for EV_ERROR ? */ + + (*mevp->me_func)(mevp->me_fd, mevp->me_type, mevp->me_param); + } +} + +struct mevent * +mevent_add(int fd, enum ev_type type, + void (*func)(int, enum ev_type, void *), void *param) +{ + struct mevent *lp, *mevp; + + if (fd < 0 || func == NULL) { + return (NULL); + } + + mevp = NULL; + + mevent_qlock(); + + /* + * Verify that the fd/type tuple is not present in any list + */ + LIST_FOREACH(lp, &global_head, me_list) { + if (lp->me_fd == fd && lp->me_type == type) { + goto exit; + } + } + + LIST_FOREACH(lp, &change_head, me_list) { + if (lp->me_fd == fd && lp->me_type == type) { + goto exit; + } + } + + /* + * Allocate an entry, populate it, and add it to the change list. + */ + mevp = malloc(sizeof(struct mevent)); + if (mevp == NULL) { + goto exit; + } + + memset(mevp, 0, sizeof(struct mevent)); + mevp->me_fd = fd; + mevp->me_type = type; + mevp->me_func = func; + mevp->me_param = param; + + LIST_INSERT_HEAD(&change_head, mevp, me_list); + mevp->me_cq = 1; + mevp->me_state = MEV_ENABLE; + mevent_notify(); + +exit: + mevent_qunlock(); + + return (mevp); +} + +static int +mevent_update(struct mevent *evp, int newstate) +{ + /* + * It's not possible to enable/disable a deleted event + */ + if (evp->me_state == MEV_DEL_PENDING) + return (EINVAL); + + /* + * No update needed if state isn't changing + */ + if (evp->me_state == newstate) + return (0); + + mevent_qlock(); + + evp->me_state = newstate; + + /* + * Place the entry onto the changed list if not already there. + */ + if (evp->me_cq == 0) { + evp->me_cq = 1; + LIST_REMOVE(evp, me_list); + LIST_INSERT_HEAD(&change_head, evp, me_list); + mevent_notify(); + } + + mevent_qunlock(); + + return (0); +} + +int +mevent_enable(struct mevent *evp) +{ + + return (mevent_update(evp, MEV_ENABLE)); +} + +int +mevent_disable(struct mevent *evp) +{ + + return (mevent_update(evp, MEV_DISABLE)); +} + +static int +mevent_delete_event(struct mevent *evp, int closefd) +{ + mevent_qlock(); + + /* + * Place the entry onto the changed list if not already there, and + * mark as to be deleted. + */ + if (evp->me_cq == 0) { + evp->me_cq = 1; + LIST_REMOVE(evp, me_list); + LIST_INSERT_HEAD(&change_head, evp, me_list); + mevent_notify(); + } + evp->me_state = MEV_DEL_PENDING; + + if (closefd) + evp->me_closefd = 1; + + mevent_qunlock(); + + return (0); +} + +int +mevent_delete(struct mevent *evp) +{ + + return (mevent_delete_event(evp, 0)); +} + +int +mevent_delete_close(struct mevent *evp) +{ + + return (mevent_delete_event(evp, 1)); +} + +static void +mevent_set_name(void) +{ + char tname[MAXCOMLEN + 1]; + + snprintf(tname, sizeof(tname), "%s mevent", vmname); + pthread_set_name_np(mevent_tid, tname); +} + +void +mevent_dispatch(void) +{ + struct kevent changelist[MEVENT_MAX]; + struct kevent eventlist[MEVENT_MAX]; + struct mevent *pipev; + int mfd; + int numev; + int ret; + + mevent_tid = pthread_self(); + mevent_set_name(); + + mfd = kqueue(); + assert(mfd > 0); + + /* + * Open the pipe that will be used for other threads to force + * the blocking kqueue call to exit by writing to it. Set the + * descriptor to non-blocking. + */ + ret = pipe(mevent_pipefd); + if (ret < 0) { + perror("pipe"); + exit(0); + } + + /* + * Add internal event handler for the pipe write fd + */ + pipev = mevent_add(mevent_pipefd[0], EVF_READ, mevent_pipe_read, NULL); + assert(pipev != NULL); + + for (;;) { + /* + * Build changelist if required. + * XXX the changelist can be put into the blocking call + * to eliminate the extra syscall. Currently better for + * debug. + */ + numev = mevent_build(mfd, changelist); + if (numev) { + ret = kevent(mfd, changelist, numev, NULL, 0, NULL); + if (ret == -1) { + perror("Error return from kevent change"); + } + } + + /* + * Block awaiting events + */ + ret = kevent(mfd, NULL, 0, eventlist, MEVENT_MAX, NULL); + if (ret == -1) { + perror("Error return from kevent monitor"); + } + + /* + * Handle reported events + */ + mevent_handle(eventlist, ret); + } +} |
