firewire: core: fix retries calculation in iso manage_channel()

If there is a permanent error condition when communicating with the IRM,
after the sixth error, the retry variable will be decremented to -1.
If, in this case, the bits in channels_mask are not yet exhausted, the
next channel is retried 2^32 times.

To fix this, check that retry is never decremented beyond zero.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 99c20f1b613..34a513725c9 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -250,8 +250,10 @@ static int manage_channel(struct fw_card *card, int irm_id, int generation,
 
                         /* 1394-1995 IRM, fall through to retry. */
                 default:
-                        if (retry--)
+                        if (retry) {
+                                retry--;
                                 i--;
+                        }
                 }
         }