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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>
This commit is contained in:
Peter Xu 2018-06-08 11:55:11 +08:00 committed by Markus Armbruster
parent d32749deb6
commit 474514668b
3 changed files with 45 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
monitor.c
View File

@ -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();
}

2
stubs/fdset.c
View File

@ -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)

3
util/osdep.c
View File

@ -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;
}