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Re: [PULL 23/26] monitor: Use LOCK_GUARD macros
From: |
Marc-André Lureau |
Subject: |
Re: [PULL 23/26] monitor: Use LOCK_GUARD macros |
Date: |
Tue, 7 Feb 2023 17:26:23 +0400 |
Hi David
On Fri, Sep 25, 2020 at 4:27 PM Dr. David Alan Gilbert (git)
<dgilbert@redhat.com> wrote:
>
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Use the lock guard macros in monitor/misc.c - saves
> a lot of unlocks in error paths, and the occasional goto.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Message-Id: <20200922095741.101911-1-dgilbert@redhat.com>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> monitor/misc.c | 44 ++++++++++++++------------------------------
> 1 file changed, 14 insertions(+), 30 deletions(-)
>
> diff --git a/monitor/misc.c b/monitor/misc.c
> index 262f2bd951..6e0da0cb96 100644
> --- a/monitor/misc.c
> +++ b/monitor/misc.c
> @@ -141,13 +141,13 @@ char *qmp_human_monitor_command(const char
> *command_line, bool has_cpu_index,
> handle_hmp_command(&hmp, command_line);
> cur_mon = old_mon;
>
> - qemu_mutex_lock(&hmp.common.mon_lock);
> - if (qstring_get_length(hmp.common.outbuf) > 0) {
> - output = g_strdup(qstring_get_str(hmp.common.outbuf));
> - } else {
> - output = g_strdup("");
> + WITH_QEMU_LOCK_GUARD(&hmp.common.mon_lock) {
> + if (qstring_get_length(hmp.common.outbuf) > 0) {
> + output = g_strdup(qstring_get_str(hmp.common.outbuf));
> + } else {
> + output = g_strdup("");
> + }
> }
> - qemu_mutex_unlock(&hmp.common.mon_lock);
>
> out:
> monitor_data_destroy(&hmp.common);
> @@ -1248,7 +1248,7 @@ void qmp_getfd(const char *fdname, Error **errp)
> return;
> }
>
> - qemu_mutex_lock(&cur_mon->mon_lock);
> + QEMU_LOCK_GUARD(&cur_mon->mon_lock);
> QLIST_FOREACH(monfd, &cur_mon->fds, next) {
> if (strcmp(monfd->name, fdname) != 0) {
> continue;
> @@ -1256,7 +1256,6 @@ void qmp_getfd(const char *fdname, Error **errp)
>
> tmp_fd = monfd->fd;
> monfd->fd = fd;
> - qemu_mutex_unlock(&cur_mon->mon_lock);
> /* Make sure close() is outside critical section */
> close(tmp_fd);
The comment doesn't look true after this patch, since the lock is
released before returning. commit 9409fc05fe2 ("monitor: protect
mon->fds with mon_lock") introduced the lock & comment. Apparently,
you didn't convert qmp_closefd() to LOCK_GUARD, presumably because of
the comment. But you did it in qmp_getfd. What's the reason for that
though, avoiding syscalls while holding the lock or am I missing
something?
thanks
> return;
> @@ -1267,7 +1266,6 @@ void qmp_getfd(const char *fdname, Error **errp)
> monfd->fd = fd;
>
> QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next);
> - qemu_mutex_unlock(&cur_mon->mon_lock);
> }
>
> void qmp_closefd(const char *fdname, Error **errp)
> @@ -1299,7 +1297,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname,
> Error **errp)
> {
> mon_fd_t *monfd;
>
> - qemu_mutex_lock(&mon->mon_lock);
> + QEMU_LOCK_GUARD(&mon->mon_lock);
> QLIST_FOREACH(monfd, &mon->fds, next) {
> int fd;
>
> @@ -1313,12 +1311,10 @@ int monitor_get_fd(Monitor *mon, const char *fdname,
> Error **errp)
> QLIST_REMOVE(monfd, next);
> g_free(monfd->name);
> g_free(monfd);
> - qemu_mutex_unlock(&mon->mon_lock);
>
> return fd;
> }
>
> - qemu_mutex_unlock(&mon->mon_lock);
> error_setg(errp, "File descriptor named '%s' has not been found",
> fdname);
> return -1;
> }
> @@ -1350,11 +1346,10 @@ void monitor_fdsets_cleanup(void)
> MonFdset *mon_fdset;
> MonFdset *mon_fdset_next;
>
> - qemu_mutex_lock(&mon_fdsets_lock);
> + QEMU_LOCK_GUARD(&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,
> @@ -1389,7 +1384,7 @@ 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);
> + QEMU_LOCK_GUARD(&mon_fdsets_lock);
> QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> if (mon_fdset->id != fdset_id) {
> continue;
> @@ -1409,12 +1404,10 @@ 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);
> @@ -1430,7 +1423,7 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
> MonFdsetFd *mon_fdset_fd;
> FdsetInfoList *fdset_list = NULL;
>
> - qemu_mutex_lock(&mon_fdsets_lock);
> + QEMU_LOCK_GUARD(&mon_fdsets_lock);
> QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info));
> FdsetFdInfoList *fdsetfd_list = NULL;
> @@ -1460,7 +1453,6 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
> fdset_info->next = fdset_list;
> fdset_list = fdset_info;
> }
> - qemu_mutex_unlock(&mon_fdsets_lock);
>
> return fdset_list;
> }
> @@ -1554,7 +1546,7 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int
> flags)
> #else
> MonFdset *mon_fdset;
>
> - qemu_mutex_lock(&mon_fdsets_lock);
> + QEMU_LOCK_GUARD(&mon_fdsets_lock);
> QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> MonFdsetFd *mon_fdset_fd;
> MonFdsetFd *mon_fdset_fd_dup;
> @@ -1569,7 +1561,6 @@ int monitor_fdset_dup_fd_add(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) {
> - qemu_mutex_unlock(&mon_fdsets_lock);
> return -1;
> }
>
> @@ -1580,25 +1571,21 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int
> flags)
> }
>
> if (fd == -1) {
> - qemu_mutex_unlock(&mon_fdsets_lock);
> errno = EACCES;
> return -1;
> }
>
> dup_fd = qemu_dup_flags(fd, flags);
> if (dup_fd == -1) {
> - qemu_mutex_unlock(&mon_fdsets_lock);
> return -1;
> }
>
> 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 dup_fd;
> }
>
> - qemu_mutex_unlock(&mon_fdsets_lock);
> errno = ENOENT;
> return -1;
> #endif
> @@ -1609,7 +1596,7 @@ static int64_t 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);
> + QEMU_LOCK_GUARD(&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) {
> @@ -1619,17 +1606,14 @@ static int64_t monitor_fdset_dup_fd_find_remove(int
> dup_fd, bool remove)
> if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
> monitor_fdset_cleanup(mon_fdset);
> }
> - goto err;
> + return -1;
> } else {
> - qemu_mutex_unlock(&mon_fdsets_lock);
> return mon_fdset->id;
> }
> }
> }
> }
>
> -err:
> - qemu_mutex_unlock(&mon_fdsets_lock);
> return -1;
> }
>
> --
> 2.26.2
>
>
--
Marc-André Lureau
- Re: [PULL 23/26] monitor: Use LOCK_GUARD macros,
Marc-André Lureau <=