From: Alan Stern <stern@rowland.harvard.edu>
Date: Wed, 12 Nov 2008 22:02:57 +0000 (-0500)
Subject: USB: EHCI: fix divide-by-zero bug
X-Git-Tag: v2.6.28-rc5~16^2~2
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=372dd6e8ed924e876f3beb598721e813ad7fa323;p=linux-2.6-omap-h63xx.git

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>
---

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 4a0c5a78b2e..a081ee65bde 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);