Re: [PATCH] TPM: cleanups

[Kylene Jo Hall <kjhall@us.ibm.com>]

> > 
> > b) user_reader_timeout does down() from within a timer handler!  That's
> >    deadlocky and is illegal - timer handlers are run from interrupt
> >    context.
> > 
> >    This should have generated a storm of runtime warnings if tested with
> >    CONFIG_PREEMPT and CONFIG_DEBUG_SPINLOCK_SLEEP.  Developers really should
> >    enable all the kernel debug options during development - they find bugs.
> > 
> >    Suggest you convert this to using schedule_work() or
> >    schedule_delayed_work(). 
> > 
> I'll look into this.

Addressed this timer/interrupt/spinlock issue with schedule_work.

Signed-off-by: Kylene Hall <kjhall@us.ibm.com>
---
diff -urpN --exclude='*.o' --exclude='*.ko' --exclude='*.orig' --exclude='*mod*' --exclude='.*' --exclude='tpm_*' --exclude='*~' --exclude='*.rej' linux-2.6.14/drivers/char/tpm/tpm.c linux-2.6.14-rc4-tpm/drivers/char/tpm/tpm.c
--- linux-2.6.14/drivers/char/tpm/tpm.c	2005-11-11 14:09:47.000000000 -0600
+++ linux-2.6.14-rc4-tpm/drivers/char/tpm/tpm.c	2005-11-11 15:40:34.000000000 -0600
@@ -43,6 +43,13 @@ static void user_reader_timeout(unsigned
 {
 	struct tpm_chip *chip = (struct tpm_chip *) ptr;
 
+	schedule_work(&chip->work);
+}
+
+static void timeout_work(void * ptr)
+{
+	struct tpm_chip *chip = (struct tpm_chip*) ptr;
+
 	down(&chip->buffer_mutex);
 	atomic_set(&chip->data_pending, 0);
 	memset(chip->data_buffer, 0, TPM_BUFSIZE);
@@ -527,6 +535,8 @@ int tpm_register_hardware(struct device 
 	init_MUTEX(&chip->tpm_mutex);
 	INIT_LIST_HEAD(&chip->list);
 
+	INIT_WORK(&chip->work, timeout_work, chip);
+
 	init_timer(&chip->user_read_timer);
 	chip->user_read_timer.function = user_reader_timeout;
 	chip->user_read_timer.data = (unsigned long) chip;
diff -urpN --exclude='*.o' --exclude='*.ko' --exclude='*.orig' --exclude='*mod*' --exclude='.*' --exclude='tpm_*' --exclude='*~' --exclude='*.rej' linux-2.6.14/drivers/char/tpm/tpm.h linux-2.6.14-rc4-tpm/drivers/char/tpm/tpm.h
--- linux-2.6.14/drivers/char/tpm/tpm.h	2005-11-11 16:44:23.000000000 -0600
+++ linux-2.6.14-rc4-tpm/drivers/char/tpm/tpm.h	2005-11-11 15:39:03.000000000 -0600
@@ -77,6 +77,7 @@ struct tpm_chip {
 	struct semaphore buffer_mutex;
 
 	struct timer_list user_read_timer;	/* user needs to claim result */
+	struct work_struct work;
 	struct semaphore tpm_mutex;	/* tpm is processing */
 
 	struct tpm_vendor_specific *vendor;