[alsa-devel] [PATCH v2 1/3] ALSA: seq: Provide card number / PID via sequencer client info

[Takashi Iwai]

On Wed, 02 Mar 2016 19:26:28 +0100,
Martin Koegler wrote:
> 
> From: Martin Koegler <martin.koegler at chello.at>
> 
> rawmidi devices expose the card number via IOCTLs, which allows to
> find the corresponding device in sysfs.
> 
> The sequencer provides no identifing data. Chromium works around this
> issue by scanning rawmidi as well as sequencer devices and matching
> them by using assumtions, how the kernel register sequencer devices.
> 
> This changes adds support for exposing the card number for kernel clients
> as well as the PID for user client.
> 
> The minor of the API version is changed to distinguish between the zero
> initialised reserved field and card number 0.
> 
> Signed-off-by: Martin Koegler <martin.koegler at chello.at>

This ABI change itself looks simple enough, so I have no big problem
to merge if you can convince other people with it :)

Clemens?


Takashi


> ---
>  include/uapi/sound/asequencer.h |  6 ++++--
>  sound/core/seq/seq_clientmgr.c  | 14 ++++++++++++++
>  sound/core/seq/seq_clientmgr.h  |  2 ++
>  3 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/sound/asequencer.h b/include/uapi/sound/asequencer.h
> index 5a5fa49..8c7da5a 100644
> --- a/include/uapi/sound/asequencer.h
> +++ b/include/uapi/sound/asequencer.h
> @@ -25,7 +25,7 @@
>  #include <sound/asound.h>
>  
>  /** version of the sequencer */
> -#define SNDRV_SEQ_VERSION SNDRV_PROTOCOL_VERSION (1, 0, 1)
> +#define SNDRV_SEQ_VERSION SNDRV_PROTOCOL_VERSION (1, 0, 2)
>  
>  /**
>   * definition of sequencer event types
> @@ -357,7 +357,9 @@ struct snd_seq_client_info {
>  	unsigned char event_filter[32];	/* event filter bitmap */
>  	int num_ports;			/* RO: number of ports */
>  	int event_lost;			/* number of lost events */
> -	char reserved[64];		/* for future use */
> +	int card;			/* RO: card number[kernel] */
> +	int pid;			/* RO: pid[user] */
> +	char reserved[56];		/* for future use */
>  };
>  
>  
> diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
> index 58e79e0..d6d9419 100644
> --- a/sound/core/seq/seq_clientmgr.c
> +++ b/sound/core/seq/seq_clientmgr.c
> @@ -364,6 +364,7 @@ static int snd_seq_open(struct inode *inode, struct file *file)
>  	/* fill client data */
>  	user->file = file;
>  	sprintf(client->name, "Client-%d", c);
> +	client->data.user.owner = get_pid(task_pid(current));
>  
>  	/* make others aware this new client */
>  	snd_seq_system_client_ev_client_start(c);
> @@ -380,6 +381,7 @@ static int snd_seq_release(struct inode *inode, struct file *file)
>  		seq_free_client(client);
>  		if (client->data.user.fifo)
>  			snd_seq_fifo_delete(&client->data.user.fifo);
> +		put_pid(client->data.user.owner);
>  		kfree(client);
>  	}
>  
> @@ -1197,6 +1199,17 @@ static void get_client_info(struct snd_seq_client *cptr,
>  	info->event_lost = cptr->event_lost;
>  	memcpy(info->event_filter, cptr->event_filter, 32);
>  	info->num_ports = cptr->num_ports;
> +
> +	if (cptr->type == USER_CLIENT)
> +		info->pid = pid_vnr(cptr->data.user.owner);
> +	else
> +		info->pid = -1;
> +
> +	if (cptr->type == KERNEL_CLIENT)
> +		info->card = cptr->data.kernel.card ? cptr->data.kernel.card->number : -1;
> +	else
> +		info->card = -1;
> +
>  	memset(info->reserved, 0, sizeof(info->reserved));
>  }
>  
> @@ -2271,6 +2284,7 @@ int snd_seq_create_kernel_client(struct snd_card *card, int client_index,
>  
>  	client->accept_input = 1;
>  	client->accept_output = 1;
> +	client->data.kernel.card = card;
>  		
>  	va_start(args, name_fmt);
>  	vsnprintf(client->name, sizeof(client->name), name_fmt, args);
> diff --git a/sound/core/seq/seq_clientmgr.h b/sound/core/seq/seq_clientmgr.h
> index 20f0a72..031462e 100644
> --- a/sound/core/seq/seq_clientmgr.h
> +++ b/sound/core/seq/seq_clientmgr.h
> @@ -33,6 +33,7 @@
>  struct snd_seq_user_client {
>  	struct file *file;	/* file struct of client */
>  	/* ... */
> +	struct pid* owner;
>  	
>  	/* fifo */
>  	struct snd_seq_fifo *fifo;	/* queue for incoming events */
> @@ -41,6 +42,7 @@ struct snd_seq_user_client {
>  
>  struct snd_seq_kernel_client {
>  	/* ... */
> +	struct snd_card* card;
>  };
>  
>  
> -- 
> 2.1.4
> 
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