From a9edfc60227a1dc5c741666ff252a6055b73b184 Mon Sep 17 00:00:00 2001 From: Karsten Wiese Date: Fri, 6 Oct 2006 16:08:27 +0200 Subject: [ALSA] Handle file operations during snd_card disconnects using static file->f_op Alsa used to kmalloc one file->f_op per file per disconnecting snd_card. This led to oopses sometimes when file->f_op was freed before __fput() finished. Patch adds a virtual device for disconnect: VDD. VDD consists of: LIST_HEAD(shutdown_files) protected by DEFINE_SPINLOCK(shutdown_mutex) static struct file_operations snd_shutdown_f_ops and functions assigned to it Additions to struct snd_monitor_file to specify if instance is hidden by VDD or not. A VDD's instance is created in snd_card_disconnect() under the card->files_lock. cleaned up in snd_card_file_remove() under the card->files_lock. Signed-off-by: Karsten Wiese Signed-off-by: Takashi Iwai Signed-off-by: Jaroslav Kysela --- sound/core/init.c | 92 +++++++++++++++++++++++++++++++------------------------ 1 file changed, 52 insertions(+), 40 deletions(-) (limited to 'sound') diff --git a/sound/core/init.c b/sound/core/init.c index d7607a25acdf..3058d626a90a 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -33,10 +33,10 @@ #include #include -struct snd_shutdown_f_ops { - struct file_operations f_ops; - struct snd_shutdown_f_ops *next; -}; +static DEFINE_SPINLOCK(shutdown_lock); +static LIST_HEAD(shutdown_files); + +static struct file_operations snd_shutdown_f_ops; static unsigned int snd_cards_lock; /* locked for registering/using */ struct snd_card *snd_cards[SNDRV_CARDS]; @@ -198,6 +198,25 @@ static ssize_t snd_disconnect_write(struct file *file, const char __user *buf, return -ENODEV; } +static int snd_disconnect_release(struct inode *inode, struct file *file) +{ + struct snd_monitor_file *df = NULL, *_df; + + spin_lock(&shutdown_lock); + list_for_each_entry(_df, &shutdown_files, shutdown_list) { + if (_df->file == file) { + df = _df; + break; + } + } + spin_unlock(&shutdown_lock); + + if (likely(df)) + return df->disconnected_f_op->release(inode, file); + + panic("%s(%p, %p) failed!", __FUNCTION__, inode, file); +} + static unsigned int snd_disconnect_poll(struct file * file, poll_table * wait) { return POLLERR | POLLNVAL; @@ -219,6 +238,22 @@ static int snd_disconnect_fasync(int fd, struct file *file, int on) return -ENODEV; } +static struct file_operations snd_shutdown_f_ops = +{ + .owner = THIS_MODULE, + .llseek = snd_disconnect_llseek, + .read = snd_disconnect_read, + .write = snd_disconnect_write, + .release = snd_disconnect_release, + .poll = snd_disconnect_poll, + .unlocked_ioctl = snd_disconnect_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = snd_disconnect_ioctl, +#endif + .mmap = snd_disconnect_mmap, + .fasync = snd_disconnect_fasync +}; + /** * snd_card_disconnect - disconnect all APIs from the file-operations (user space) * @card: soundcard structure @@ -234,9 +269,6 @@ int snd_card_disconnect(struct snd_card *card) { struct snd_monitor_file *mfile; struct file *file; - struct snd_shutdown_f_ops *s_f_ops; - struct file_operations *f_ops; - const struct file_operations *old_f_ops; int err; spin_lock(&card->files_lock); @@ -261,34 +293,14 @@ int snd_card_disconnect(struct snd_card *card) /* it's critical part, use endless loop */ /* we have no room to fail */ - s_f_ops = kmalloc(sizeof(struct snd_shutdown_f_ops), GFP_ATOMIC); - if (s_f_ops == NULL) - panic("Atomic allocation failed for snd_shutdown_f_ops!"); - - f_ops = &s_f_ops->f_ops; - - memset(f_ops, 0, sizeof(*f_ops)); - f_ops->owner = file->f_op->owner; - f_ops->release = file->f_op->release; - f_ops->llseek = snd_disconnect_llseek; - f_ops->read = snd_disconnect_read; - f_ops->write = snd_disconnect_write; - f_ops->poll = snd_disconnect_poll; - f_ops->unlocked_ioctl = snd_disconnect_ioctl; -#ifdef CONFIG_COMPAT - f_ops->compat_ioctl = snd_disconnect_ioctl; -#endif - f_ops->mmap = snd_disconnect_mmap; - f_ops->fasync = snd_disconnect_fasync; + mfile->disconnected_f_op = mfile->file->f_op; - s_f_ops->next = card->s_f_ops; - card->s_f_ops = s_f_ops; - - f_ops = fops_get(f_ops); + spin_lock(&shutdown_lock); + list_add(&mfile->shutdown_list, &shutdown_files); + spin_unlock(&shutdown_lock); - old_f_ops = file->f_op; - file->f_op = f_ops; /* must be atomic */ - fops_put(old_f_ops); + fops_get(&snd_shutdown_f_ops); + mfile->file->f_op = &snd_shutdown_f_ops; mfile = mfile->next; } @@ -326,8 +338,6 @@ EXPORT_SYMBOL(snd_card_disconnect); */ static int snd_card_do_free(struct snd_card *card) { - struct snd_shutdown_f_ops *s_f_ops; - #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE) if (snd_mixer_oss_notify_callback) snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE); @@ -351,11 +361,6 @@ static int snd_card_do_free(struct snd_card *card) snd_printk(KERN_WARNING "unable to free card info\n"); /* Not fatal error */ } - while (card->s_f_ops) { - s_f_ops = card->s_f_ops; - card->s_f_ops = s_f_ops->next; - kfree(s_f_ops); - } kfree(card); return 0; } @@ -670,6 +675,7 @@ int snd_card_file_add(struct snd_card *card, struct file *file) if (mfile == NULL) return -ENOMEM; mfile->file = file; + mfile->disconnected_f_op = NULL; mfile->next = NULL; spin_lock(&card->files_lock); if (card->shutdown) { @@ -716,6 +722,12 @@ int snd_card_file_remove(struct snd_card *card, struct file *file) pfile = mfile; mfile = mfile->next; } + if (mfile && mfile->disconnected_f_op) { + fops_put(mfile->disconnected_f_op); + spin_lock(&shutdown_lock); + list_del(&mfile->shutdown_list); + spin_unlock(&shutdown_lock); + } if (card->files == NULL) last_close = 1; spin_unlock(&card->files_lock); -- cgit v1.2.2