[PATCH 3.13 062/140] xhci: Avoid infinite loop when sg urb requires too many trbs

[Greg Kroah-Hartman]

3.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>

commit d6c9ea9069af684358efedcaf2f2f687f51c58ee upstream.

Currently prepare_ring() returns -ENOMEM if the urb won't fit into a
single ring segment.  usb_sg_wait() treats this error as a temporary
condition and will keep retrying until something else goes wrong.

The number of retries should be limited in usb_sg_wait(), but also
prepare_ring() should not return an error code that suggests it might
be worth retrying.  Change it to -EINVAL.

Reported-by: jidanni@xxxxxxxxxxx
References: http://bugs.debian.org/733907
Fixes: 35773dac5f86 ('usb: xhci: Link TRB must not occur within a USB payload burst')
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci-ring.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3008,7 +3008,7 @@ static int prepare_ring(struct xhci_hcd
 			if (num_trbs >= TRBS_PER_SEGMENT) {
 				xhci_err(xhci, "Too many fragments %d, max %d\n",
 						num_trbs, TRBS_PER_SEGMENT - 1);
-				return -ENOMEM;
+				return -EINVAL;
 			}
 
 			nop_cmd = cpu_to_le32(TRB_TYPE(TRB_TR_NOOP) |


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