ALSA: seq: Register kernel port with full information

The current ALSA sequencer core tries to register the new kernel
sequencer port on the list at first, then fill up the port
information.  This means that user-space may sneak the wrong
information before the actual data is filled, which isn't ideal.
Although the user-space should try to query the port info after the
port registration notification is sent out, it'd be still better to
have a port available with the full info from the beginning.

This patch changes the sequencer port creation and registration
procedure; now split to two steps, for creation and insertion, and the
port is registered after the information is filled.

Link: https://sashiko.dev/#/patchset/20260518194023.1667857-1-maoyixie.tju%40gmail.com
Link: https://patch.msgid.link/20260519094254.465041-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index 5719637575a9113df0aca09544654c301a79115f..19d6fea012f6ae37d5bc4c0565bf49b989464542 100644 (file)
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -1287,7 +1287,7 @@ static int snd_seq_ioctl_create_port(struct snd_seq_client *client, void *arg)
                port_idx = -1;
        if (port_idx >= SNDRV_SEQ_ADDRESS_UNKNOWN)
                return -EINVAL;
-       err = snd_seq_create_port(client, port_idx, &port);
+       err = snd_seq_create_port(client, &port);
        if (err < 0)
                return err;
 
@@ -1309,6 +1309,11 @@ static int snd_seq_ioctl_create_port(struct snd_seq_client *client, void *arg)
        info->addr = port->addr;
 
        snd_seq_set_port_info(port, info);
+       err = snd_seq_insert_port(client, port_idx, port);
+       if (err < 0) {
+               kfree(port);
+               return err;
+       }
        if (info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT)
                client->ump_endpoint_port = port->addr.port;
        snd_seq_system_client_ev_port_start(port->addr.client, port->addr.port);

diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c
index 31ab4681c60124f4cfc11ad0d318489ad30e29a7..17daacd4476aaa7e5bf368a3e11d4246cf632c97 100644 (file)
--- a/sound/core/seq/seq_ports.c
+++ b/sound/core/seq/seq_ports.c
@@ -108,14 +108,13 @@ static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
 }
 
 
-/* create a port, port number or a negative error code is returned
+/* create a port, 0 on success or a negative error code is returned
  * the caller needs to unref the port via snd_seq_port_unlock() appropriately
  */
-int snd_seq_create_port(struct snd_seq_client *client, int port,
+int snd_seq_create_port(struct snd_seq_client *client,
                        struct snd_seq_client_port **port_ret)
 {
-       struct snd_seq_client_port *new_port, *p;
-       int num;
+       struct snd_seq_client_port *new_port;
        
        *port_ret = NULL;
 
@@ -141,15 +140,25 @@ int snd_seq_create_port(struct snd_seq_client *client, int port,
        port_subs_info_init(&new_port->c_dest);
        snd_use_lock_use(&new_port->use_lock);
 
+       *port_ret = new_port;
+
+       return 0;
+}
+
+/* insert the port; return the port address or a negative error code */
+int snd_seq_insert_port(struct snd_seq_client *client, int port,
+                       struct snd_seq_client_port *new_port)
+{
+       struct snd_seq_client_port *p;
+       int num;
+
        num = max(port, 0);
        guard(mutex)(&client->ports_mutex);
        guard(write_lock_irq)(&client->ports_lock);
        struct list_head *insert_before = &client->ports_list_head;
        list_for_each_entry(p, &client->ports_list_head, list) {
-               if (p->addr.port == port) {
-                       kfree(new_port);
+               if (p->addr.port == port)
                        return -EBUSY;
-               }
                if (p->addr.port > num) {
                        insert_before = &p->list;
                        break;
@@ -162,7 +171,6 @@ int snd_seq_create_port(struct snd_seq_client *client, int port,
        client->num_ports++;
        new_port->addr.port = num;      /* store the port number in the port */
        sprintf(new_port->name, "port-%d", num);
-       *port_ret = new_port;
 
        return num;
 }

diff --git a/sound/core/seq/seq_ports.h b/sound/core/seq/seq_ports.h
index 40ed6cf7cb90bb34b4bf4fbab560e01346f78d77..b689c0f4867c445e26f6f645a11b4d0fc0c941cd 100644 (file)
--- a/sound/core/seq/seq_ports.h
+++ b/sound/core/seq/seq_ports.h
@@ -98,10 +98,14 @@ struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *cl
 
 DEFINE_FREE(snd_seq_port, struct snd_seq_client_port *, if (!IS_ERR_OR_NULL(_T)) snd_seq_port_unlock(_T))
 
-/* create a port, port number or a negative error code is returned */
-int snd_seq_create_port(struct snd_seq_client *client, int port_index,
+/* create a port, 0 on success or a negative error code is returned */
+int snd_seq_create_port(struct snd_seq_client *client,
                        struct snd_seq_client_port **port_ret);
 
+/* insert the port; return the port address or a negative error code */
+int snd_seq_insert_port(struct snd_seq_client *client, int port,
+                       struct snd_seq_client_port *new_port);
+
 /* delete a port */
 int snd_seq_delete_port(struct snd_seq_client *client, int port);