From 372dd6e8ed924e876f3beb598721e813ad7fa323 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Wed, 12 Nov 2008 17:02:57 -0500
Subject: [PATCH] USB: EHCI: fix divide-by-zero bug
This patch (as1164) fixes a bug in the EHCI scheduler. The interval
value it uses is already in linear format, not logarithmically coded.
The existing code can sometimes crash the system by trying to divide
by zero.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: David Brownell <david-b@pacbell.net>
Cc: Stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/usb/host/ehci-sched.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 4a0c5a78b2ed..a081ee65bde6 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -918,7 +918,7 @@ iso_stream_init (
*/
stream->usecs = HS_USECS_ISO (maxp);
bandwidth = stream->usecs * 8;
- bandwidth /= 1 << (interval - 1);
+ bandwidth /= interval;
} else {
u32 addr;
@@ -951,7 +951,7 @@ iso_stream_init (
} else
stream->raw_mask = smask_out [hs_transfers - 1];
bandwidth = stream->usecs + stream->c_usecs;
- bandwidth /= 1 << (interval + 2);
+ bandwidth /= interval << 3;
/* stream->splits gets created from raw_mask later */
stream->address = cpu_to_hc32(ehci, addr);
--
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