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Commit 25d27ede authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Takashi Iwai
Browse files

control: use reference-counted pid 



Instead of storing the PID number, take a reference to the task's pid
structure.  This protects against duplicates due to PID overflows, and
using pid_vnr() ensures that the PID returned by snd_ctl_elem_info() is
correct as seen from the current namespace.

Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 31cef707

include/sound/control.h

+3 −1
Original line number Diff line number Diff line
@@ -86,10 +86,12 @@ struct snd_kctl_event { 


#define snd_kctl_event(n) list_entry(n, struct snd_kctl_event, list)



struct pid;



struct snd_ctl_file {

	struct list_head list;		/* list of all control files */

	struct snd_card *card;

	pid_t pid;

	struct pid *pid;

	int prefer_pcm_subdevice;

	int prefer_rawmidi_subdevice;

	wait_queue_head_t change_sleep;

sound/core/control.c

+3 −2
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ static int snd_ctl_open(struct inode *inode, struct file *file) 
	ctl->card = card;

	ctl->prefer_pcm_subdevice = -1;

	ctl->prefer_rawmidi_subdevice = -1;

	ctl->pid = current->pid;

	ctl->pid = get_pid(task_pid(current));

	file->private_data = ctl;

	write_lock_irqsave(&card->ctl_files_rwlock, flags);

	list_add_tail(&ctl->list, &card->ctl_files);
@@ -125,6 +125,7 @@ static int snd_ctl_release(struct inode *inode, struct file *file) 
				control->vd[idx].owner = NULL;

	up_write(&card->controls_rwsem);

	snd_ctl_empty_read_queue(ctl);

	put_pid(ctl->pid);

	kfree(ctl);

	module_put(card->module);

	snd_card_file_remove(card, file);
@@ -672,7 +673,7 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl, 
			info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;

			if (vd->owner == ctl)

				info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;

			info->owner = vd->owner->pid;

			info->owner = pid_vnr(vd->owner->pid);

		} else {

			info->owner = -1;

		}

sound/core/pcm.c

+1 −1
Original line number Diff line number Diff line
@@ -809,7 +809,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, 
	card = pcm->card;

	read_lock(&card->ctl_files_rwlock);

	list_for_each_entry(kctl, &card->ctl_files, list) {

		if (kctl->pid == current->pid) {

		if (kctl->pid == task_pid(current)) {

			prefer_subdevice = kctl->prefer_pcm_subdevice;

			if (prefer_subdevice != -1)

				break;

sound/core/rawmidi.c

+1 −1
Original line number Diff line number Diff line
@@ -415,7 +415,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file) 
		subdevice = -1;

		read_lock(&card->ctl_files_rwlock);

		list_for_each_entry(kctl, &card->ctl_files, list) {

			if (kctl->pid == current->pid) {

			if (kctl->pid == task_pid(current)) {

				subdevice = kctl->prefer_rawmidi_subdevice;

				if (subdevice != -1)

					break;