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

[Clemens Ladisch]

Takashi Iwai wrote:
> Martin Koegler wrote:
>> 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 :)

Acked-by: Clemens Ladisch <clemens at ladisch.de>

>> ---
>>  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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>>
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