[PULL] Updates to tpm_write() error checking

[PULL] Updates to tpm_write() error checking

[Kent Yoder]

Hi James,

The following changes since commit bf5308344527d015ac9a6d2bda4ad4d40fd7d943:

  Merge tag 'v3.6-rc7' into next (2012-09-28 13:37:32 +1000)

are available in the git repository at:


  git://github.com/shpedoikal/linux.git tpmdd-next-v3.6

for you to fetch changes up to abce9ac292e13da367bbd22c1f7669f988d931ac:

  tpm: Propagate error from tpm_transmit to fix a timeout hang (2012-10-10 11:34:31 -0500)

----------------------------------------------------------------
Peter Huewe (1):
      tpm: Propagate error from tpm_transmit to fix a timeout hang

 drivers/char/tpm/tpm.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 6724615..4caef33 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1182,17 +1182,20 @@ ssize_t tpm_write(struct file *file, const char __user *buf,
 		  size_t size, loff_t *off)
 {
 	struct tpm_chip *chip = file->private_data;
-	size_t in_size = size, out_size;
+	size_t in_size = size;
+	ssize_t out_size;
 
 	/* cannot perform a write until the read has cleared
-	   either via tpm_read or a user_read_timer timeout */
-	while (atomic_read(&chip->data_pending) != 0)
-		msleep(TPM_TIMEOUT);
-
-	mutex_lock(&chip->buffer_mutex);
+	   either via tpm_read or a user_read_timer timeout.
+	   This also prevents splitted buffered writes from blocking here.
+	*/
+	if (atomic_read(&chip->data_pending) != 0)
+		return -EBUSY;
 
 	if (in_size > TPM_BUFSIZE)
-		in_size = TPM_BUFSIZE;
+		return -E2BIG;
+
+	mutex_lock(&chip->buffer_mutex);
 
 	if (copy_from_user
 	    (chip->data_buffer, (void __user *) buf, in_size)) {
@@ -1202,6 +1205,10 @@ ssize_t tpm_write(struct file *file, const char __user *buf,
 
 	/* atomic tpm command send and result receive */
 	out_size = tpm_transmit(chip, chip->data_buffer, TPM_BUFSIZE);
+	if (out_size < 0) {
+		mutex_unlock(&chip->buffer_mutex);
+		return out_size;
+	}
 
 	atomic_set(&chip->data_pending, out_size);
 	mutex_unlock(&chip->buffer_mutex);