From 474514668b47c9d2148b526e379ffbb6764d9a9e Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 8 Jun 2018 11:55:11 +0800 Subject: [PATCH] monitor: add lock to protect mon_fdsets Introduce a new global big lock for mon_fdsets. Take it where needed. The monitor_fdset_get_fd() handling is a bit tricky: now we need to call qemu_mutex_unlock() which might pollute errno, so we need to make sure the correct errno be passed up to the callers. To make things simpler, we let monitor_fdset_get_fd() return the -errno directly when error happens, then in qemu_open() we move it back into errno. Reviewed-by: Stefan Hajnoczi Reviewed-by: Markus Armbruster Signed-off-by: Peter Xu Message-Id: <20180608035511.7439-8-peterx@redhat.com> Signed-off-by: Markus Armbruster --- monitor.c | 52 +++++++++++++++++++++++++++++++++++++++++---------- stubs/fdset.c | 2 +- util/osdep.c | 3 ++- 3 files changed, 45 insertions(+), 12 deletions(-) diff --git a/monitor.c b/monitor.c index e805e40799..885e000f9b 100644 --- a/monitor.c +++ b/monitor.c @@ -271,7 +271,10 @@ static QemuMutex monitor_lock; static GHashTable *monitor_qapi_event_state; static QTAILQ_HEAD(mon_list, Monitor) mon_list; +/* Protects mon_fdsets */ +static QemuMutex mon_fdsets_lock; static QLIST_HEAD(mon_fdsets, MonFdset) mon_fdsets; + static int mon_refcount; static mon_cmd_t mon_cmds[]; @@ -2319,9 +2322,11 @@ static void monitor_fdsets_cleanup(void) MonFdset *mon_fdset; MonFdset *mon_fdset_next; + qemu_mutex_lock(&mon_fdsets_lock); QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) { monitor_fdset_cleanup(mon_fdset); } + qemu_mutex_unlock(&mon_fdsets_lock); } AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque, @@ -2356,6 +2361,7 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp) MonFdsetFd *mon_fdset_fd; char fd_str[60]; + qemu_mutex_lock(&mon_fdsets_lock); QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { if (mon_fdset->id != fdset_id) { continue; @@ -2375,10 +2381,12 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp) goto error; } monitor_fdset_cleanup(mon_fdset); + qemu_mutex_unlock(&mon_fdsets_lock); return; } error: + qemu_mutex_unlock(&mon_fdsets_lock); if (has_fd) { snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64, fdset_id, fd); @@ -2394,6 +2402,7 @@ FdsetInfoList *qmp_query_fdsets(Error **errp) MonFdsetFd *mon_fdset_fd; FdsetInfoList *fdset_list = NULL; + qemu_mutex_lock(&mon_fdsets_lock); QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info)); FdsetFdInfoList *fdsetfd_list = NULL; @@ -2423,6 +2432,7 @@ FdsetInfoList *qmp_query_fdsets(Error **errp) fdset_info->next = fdset_list; fdset_list = fdset_info; } + qemu_mutex_unlock(&mon_fdsets_lock); return fdset_list; } @@ -2435,6 +2445,7 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id, MonFdsetFd *mon_fdset_fd; AddfdInfo *fdinfo; + qemu_mutex_lock(&mon_fdsets_lock); if (has_fdset_id) { QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { /* Break if match found or match impossible due to ordering by ID */ @@ -2455,6 +2466,7 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id, if (fdset_id < 0) { error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id", "a non-negative value"); + qemu_mutex_unlock(&mon_fdsets_lock); return NULL; } /* Use specified fdset ID */ @@ -2505,16 +2517,21 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id, fdinfo->fdset_id = mon_fdset->id; fdinfo->fd = mon_fdset_fd->fd; + qemu_mutex_unlock(&mon_fdsets_lock); return fdinfo; } int monitor_fdset_get_fd(int64_t fdset_id, int flags) { -#ifndef _WIN32 +#ifdef _WIN32 + return -ENOENT; +#else MonFdset *mon_fdset; MonFdsetFd *mon_fdset_fd; int mon_fd_flags; + int ret; + qemu_mutex_lock(&mon_fdsets_lock); QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { if (mon_fdset->id != fdset_id) { continue; @@ -2522,20 +2539,24 @@ int monitor_fdset_get_fd(int64_t fdset_id, int flags) QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) { mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL); if (mon_fd_flags == -1) { - return -1; + ret = -errno; + goto out; } if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) { - return mon_fdset_fd->fd; + ret = mon_fdset_fd->fd; + goto out; } } - errno = EACCES; - return -1; + ret = -EACCES; + goto out; } -#endif + ret = -ENOENT; - errno = ENOENT; - return -1; +out: + qemu_mutex_unlock(&mon_fdsets_lock); + return ret; +#endif } int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd) @@ -2543,20 +2564,25 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd) MonFdset *mon_fdset; MonFdsetFd *mon_fdset_fd_dup; + qemu_mutex_lock(&mon_fdsets_lock); QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { if (mon_fdset->id != fdset_id) { continue; } QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) { if (mon_fdset_fd_dup->fd == dup_fd) { - return -1; + goto err; } } mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup)); mon_fdset_fd_dup->fd = dup_fd; QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next); + qemu_mutex_unlock(&mon_fdsets_lock); return 0; } + +err: + qemu_mutex_unlock(&mon_fdsets_lock); return -1; } @@ -2565,6 +2591,7 @@ static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove) MonFdset *mon_fdset; MonFdsetFd *mon_fdset_fd_dup; + qemu_mutex_lock(&mon_fdsets_lock); QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) { if (mon_fdset_fd_dup->fd == dup_fd) { @@ -2573,13 +2600,17 @@ static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove) if (QLIST_EMPTY(&mon_fdset->dup_fds)) { monitor_fdset_cleanup(mon_fdset); } - return -1; + goto err; } else { + qemu_mutex_unlock(&mon_fdsets_lock); return mon_fdset->id; } } } } + +err: + qemu_mutex_unlock(&mon_fdsets_lock); return -1; } @@ -4519,6 +4550,7 @@ void monitor_init_globals(void) monitor_qapi_event_init(); sortcmdlist(); qemu_mutex_init(&monitor_lock); + qemu_mutex_init(&mon_fdsets_lock); monitor_iothread_init(); } diff --git a/stubs/fdset.c b/stubs/fdset.c index 6020cf28c8..4f3edf2ea4 100644 --- a/stubs/fdset.c +++ b/stubs/fdset.c @@ -14,7 +14,7 @@ int monitor_fdset_dup_fd_find(int dup_fd) int monitor_fdset_get_fd(int64_t fdset_id, int flags) { - return -1; + return -ENOENT; } void monitor_fdset_dup_fd_remove(int dupfd) diff --git a/util/osdep.c b/util/osdep.c index a73de0e1ba..ea51d500b6 100644 --- a/util/osdep.c +++ b/util/osdep.c @@ -302,7 +302,8 @@ int qemu_open(const char *name, int flags, ...) } fd = monitor_fdset_get_fd(fdset_id, flags); - if (fd == -1) { + if (fd < 0) { + errno = -fd; return -1; }