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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>
This commit is contained in:
Parag Warudkar 2007-05-08 00:31:09 -07:00 committed by Linus Torvalds
parent 53ab97a1c1
commit 8e39c933b1
1 changed files with 8 additions and 4 deletions
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12
drivers/char/tpm/tpm.c
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@ -942,12 +942,12 @@ int tpm_release(struct inode *inode, struct file *file)
{
struct tpm_chip *chip = file->private_data;
flush_scheduled_work();
spin_lock(&driver_lock);
file->private_data = NULL;
chip->num_opens--;
del_singleshot_timer_sync(&chip->user_read_timer);
flush_scheduled_work();
atomic_set(&chip->data_pending, 0);
chip->num_opens--;
put_device(chip->dev);
kfree(chip->data_buffer);
spin_unlock(&driver_lock);
@ -1097,8 +1097,13 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
/* Driver specific per-device data */
chip = kzalloc(sizeof(*chip), GFP_KERNEL);
if (chip == NULL)
devname = kmalloc(DEVNAME_SIZE, GFP_KERNEL);
if (chip == NULL || devname == NULL) {
kfree(chip);
kfree(devname);
return NULL;
}
init_MUTEX(&chip->buffer_mutex);
init_MUTEX(&chip->tpm_mutex);
@ -1124,7 +1129,6 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
set_bit(chip->dev_num, dev_mask);
devname = kmalloc(DEVNAME_SIZE, GFP_KERNEL);
scnprintf(devname, DEVNAME_SIZE, "%s%d", "tpm", chip->dev_num);
chip->vendor.miscdev.name = devname;