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tpm: fix sleep-in-spinlock
flush_scheduled_work() can sleep, and we're calling it under spinlock. AFAICS, moving flush_scheduled_work before spin_lock() should not cause any problems. Reason being - The only thing that can race against tpm_release is tpm_open (tpm_release is called when last reference to the file is closed and only thing that can happen after that is tpm_open??) and tpm_open acquires driver_lock and more over it bails out with EBUSY if chip->num_opens is greater than 0. I also moved chip->num_pending-- to after deleting timer and setting data pending as it looks more correct for the paranoid although it probably doesn't matter as it is guarded by driver_lock. None the less this change should not cause problems. While I was at it I noticed a missing NULL check in tpm_register_hardware which is fixed with this patch as well. Signed-off-by: Parag Warudkar <parag.warudkar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -942,12 +942,12 @@ int tpm_release(struct inode *inode, struct file *file)
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{
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struct tpm_chip *chip = file->private_data;
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flush_scheduled_work();
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spin_lock(&driver_lock);
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file->private_data = NULL;
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chip->num_opens--;
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del_singleshot_timer_sync(&chip->user_read_timer);
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flush_scheduled_work();
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atomic_set(&chip->data_pending, 0);
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chip->num_opens--;
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put_device(chip->dev);
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kfree(chip->data_buffer);
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spin_unlock(&driver_lock);
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@ -1097,8 +1097,13 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
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/* Driver specific per-device data */
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chip = kzalloc(sizeof(*chip), GFP_KERNEL);
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if (chip == NULL)
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devname = kmalloc(DEVNAME_SIZE, GFP_KERNEL);
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if (chip == NULL || devname == NULL) {
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kfree(chip);
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kfree(devname);
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return NULL;
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}
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init_MUTEX(&chip->buffer_mutex);
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init_MUTEX(&chip->tpm_mutex);
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@ -1124,7 +1129,6 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
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set_bit(chip->dev_num, dev_mask);
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devname = kmalloc(DEVNAME_SIZE, GFP_KERNEL);
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scnprintf(devname, DEVNAME_SIZE, "%s%d", "tpm", chip->dev_num);
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chip->vendor.miscdev.name = devname;
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