On Thu, Nov 18, 2021 at 11:58:25PM +0100, mwilck@xxxxxxxx wrote:
> From: Martin Wilck <mwilck@xxxxxxxx>
>
> The list of clients is never changed anywhere except in
> uxsock_listen(). No need to lock.
>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> ---
> multipathd/uxlsnr.c | 33 ++++++---------------------------
> 1 file changed, 6 insertions(+), 27 deletions(-)
>
> diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
> index 6213454..24db377 100644
> --- a/multipathd/uxlsnr.c
> +++ b/multipathd/uxlsnr.c
> @@ -89,7 +89,6 @@ enum {
> static __attribute__((unused)) char ___a[-(MIN_POLLS <= 0)];
>
> static LIST_HEAD(clients);
> -static pthread_mutex_t client_lock = PTHREAD_MUTEX_INITIALIZER;
> static struct pollfd *polls;
> static int notify_fd = -1;
> static int idle_fd = -1;
> @@ -136,15 +135,13 @@ static void new_client(int ux_sock)
> c->is_root = _socket_client_is_root(c->fd);
>
> /* put it in our linked list */
> - pthread_mutex_lock(&client_lock);
> list_add_tail(&c->node, &clients);
> - pthread_mutex_unlock(&client_lock);
> }
>
> /*
> * kill off a dead client
> */
> -static void _dead_client(struct client *c)
> +static void dead_client(struct client *c)
> {
> int fd = c->fd;
> list_del_init(&c->node);
> @@ -156,14 +153,6 @@ static void _dead_client(struct client *c)
> close(fd);
> }
>
> -static void dead_client(struct client *c)
> -{
> - pthread_cleanup_push(cleanup_mutex, &client_lock);
> - pthread_mutex_lock(&client_lock);
> - _dead_client(c);
> - pthread_cleanup_pop(1);
> -}
> -
> static void free_polls (void)
> {
> if (polls)
> @@ -180,11 +169,9 @@ void uxsock_cleanup(void *arg)
> close(notify_fd);
> free(watch_config_dir);
>
> - pthread_mutex_lock(&client_lock);
> list_for_each_entry_safe(client_loop, client_tmp, &clients, node) {
> - _dead_client(client_loop);
> + dead_client(client_loop);
> }
> - pthread_mutex_unlock(&client_lock);
>
> cli_exit();
> free_polls();
> @@ -308,8 +295,7 @@ static void handle_inotify(int fd, struct watch_descriptors *wds)
> static const struct timespec ts_zero = { .tv_sec = 0, };
> static const struct timespec ts_max = { .tv_sec = LONG_MAX, .tv_nsec = 999999999 };
>
> -/* call with clients lock held */
> -static struct timespec *__get_soonest_timeout(struct timespec *ts)
> +static struct timespec *get_soonest_timeout(struct timespec *ts)
> {
> struct timespec ts_min = ts_max, now;
> bool any = false;
> @@ -336,8 +322,7 @@ static struct timespec *__get_soonest_timeout(struct timespec *ts)
> return ts;
> }
>
> -/* call with clients lock held */
> -static bool __need_vecs_lock(void)
> +static bool need_vecs_lock(void)
> {
> struct client *c;
>
> @@ -614,7 +599,6 @@ void *uxsock_listen(long ux_sock, void *trigger_data)
> /* conf->sequence_nr will be 1 when uxsock_listen is first called */
> unsigned int sequence_nr = 0;
> struct watch_descriptors wds = { .conf_wd = -1, .dir_wd = -1 };
> - bool need_lock = false;
> struct vectors *vecs = trigger_data;
>
> condlog(3, "uxsock: startup listener");
> @@ -645,8 +629,6 @@ void *uxsock_listen(long ux_sock, void *trigger_data)
> struct timespec __timeout, *timeout;
>
> /* setup for a poll */
> - pthread_mutex_lock(&client_lock);
> - pthread_cleanup_push(cleanup_mutex, &client_lock);
> num_clients = 0;
> list_for_each_entry(c, &clients, node) {
> num_clients++;
> @@ -686,9 +668,8 @@ void *uxsock_listen(long ux_sock, void *trigger_data)
> else
> polls[POLLFD_NOTIFY].events = POLLIN;
>
> - need_lock = __need_vecs_lock();
> polls[POLLFD_IDLE].fd = idle_fd;
> - if (need_lock)
> + if (need_vecs_lock())
> polls[POLLFD_IDLE].events = POLLIN;
> else
> polls[POLLFD_IDLE].events = 0;
> @@ -713,9 +694,7 @@ void *uxsock_listen(long ux_sock, void *trigger_data)
> break;
> }
> n_pfds = i;
> - timeout = __get_soonest_timeout(&__timeout);
> -
> - pthread_cleanup_pop(1);
> + timeout = get_soonest_timeout(&__timeout);
>
> /* most of our life is spent in this call */
> poll_count = ppoll(polls, n_pfds, timeout, &mask);
> --
> 2.33.1
--
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