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 <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180608035511.7439-8-peterx@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/monitor.c b/monitor.c
index e805e40..885e000 100644
--- a/monitor.c
+++ b/monitor.c
@@ -271,7 +271,10 @@
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 @@
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 @@
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 @@
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 @@
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 @@
fdset_info->next = fdset_list;
fdset_list = fdset_info;
}
+ qemu_mutex_unlock(&mon_fdsets_lock);
return fdset_list;
}
@@ -2435,6 +2445,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
monitor_qapi_event_init();
sortcmdlist();
qemu_mutex_init(&monitor_lock);
+ qemu_mutex_init(&mon_fdsets_lock);
monitor_iothread_init();
}
