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| author | Paul Zimmerman <Paul.Zimmerman@synopsys.com> | 2011-02-12 14:07:20 -0800 |
|---|---|---|
| committer | Sarah Sharp <sarah.a.sharp@linux.intel.com> | 2011-02-20 07:01:27 -0800 |
| commit | 5807795bd4dececdf553719cc02869e633395787 (patch) | |
| tree | d200e995de9dffbc6e6e44a8da4fcdc5f37a94aa /drivers/usb | |
| parent | a2490187011cc2263117626615a581927d19f1d3 (diff) | |
| download | lwn-5807795bd4dececdf553719cc02869e633395787.tar.gz lwn-5807795bd4dececdf553719cc02869e633395787.zip | |
xhci: Fix errors in the running total calculations in the TRB math
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.
Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@kernel.org
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 1071411d6dfc..dbbeec96ce1d 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -2369,6 +2369,7 @@ 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++; @@ -2661,6 +2662,7 @@ 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 @@ -2884,6 +2886,7 @@ static int count_isoc_trbs_needed(struct xhci_hcd *xhci, td_len = urb->iso_frame_desc[i].length; running_total = TRB_MAX_BUFF_SIZE - (addr & (TRB_MAX_BUFF_SIZE - 1)); + running_total &= TRB_MAX_BUFF_SIZE - 1; if (running_total != 0) num_trbs++; |