From: Paul Zimmerman Date: Sat, 12 Feb 2011 22:07:20 +0000 (-0800) Subject: xhci: Fix errors in the running total calculations in the TRB math X-Git-Tag: v2.6.34.10~115 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=31331bfac21cfeef1064dc94bf955f76e91a93c4;p=thirdparty%2Fkernel%2Fstable.git xhci: Fix errors in the running total calculations in the TRB math commit 5807795bd4dececdf553719cc02869e633395787 upstream. Calculations like running_total = TRB_MAX_BUFF_SIZE - (sg_dma_address(sg) & (TRB_MAX_BUFF_SIZE - 1)); if (running_total != 0) num_trbs++; are incorrect, because running_total can never be zero, so the if() expression will never be true. I think the intention was that running_total be in the range of 0 to TRB_MAX_BUFF_SIZE-1, not 1 to TRB_MAX_BUFF_SIZE. So adding a running_total &= TRB_MAX_BUFF_SIZE - 1; fixes the problem. This patch should be queued for stable kernels back to 2.6.31. [PG: 34 doesn't have count_isoc_trbs_needed() hence this has only two of the three upstream running_total changes.] Signed-off-by: Paul Zimmerman Signed-off-by: Sarah Sharp Signed-off-by: Paul Gortmaker --- diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 8bf5563181017..e4afa994257f5 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1711,6 +1711,7 @@ static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb) /* Scatter gather list entries may cross 64KB boundaries */ running_total = TRB_MAX_BUFF_SIZE - (sg_dma_address(sg) & (TRB_MAX_BUFF_SIZE - 1)); + running_total &= TRB_MAX_BUFF_SIZE - 1; if (running_total != 0) num_trbs++; @@ -1978,6 +1979,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags, /* How much data is (potentially) left before the 64KB boundary? */ running_total = TRB_MAX_BUFF_SIZE - (urb->transfer_dma & (TRB_MAX_BUFF_SIZE - 1)); + running_total &= TRB_MAX_BUFF_SIZE - 1; /* If there's some data on this 64KB chunk, or we have to send a * zero-length transfer, we need at least one TRB