[PATCH 3.12 062/133] xhci: Avoid infinite loop when sg urb requires too many trbs

From: Greg Kroah-Hartman
Date: Tue Feb 04 2014 - 17:10:50 EST


3.12-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
@@ -2964,7 +2964,7 @@ 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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