[PATCH] tpm: locking fix

Use schedule_work() to avoid down()-in-timer-handler problem.

Signed-off-by: Kylene Hall <kjhall@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 10 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 1a53da99b58..0b283d24673 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -43,6 +43,13 @@ static void user_reader_timeout(unsigned long ptr)
 {
         struct tpm_chip *chip = (struct tpm_chip *) ptr;
 
+        schedule_work(&chip->work);
+}
+
+static void timeout_work(void * ptr)
+{
+        struct tpm_chip *chip = ptr;
+
         down(&chip->buffer_mutex);
         atomic_set(&chip->data_pending, 0);
         memset(chip->data_buffer, 0, TPM_BUFSIZE);
@@ -527,6 +534,8 @@ int tpm_register_hardware(struct device *dev, struct tpm_vendor_specific *entry)
         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 --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index ad51c653803..159882ca69d 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -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;