Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751874AbZDUXnw (ORCPT ); Tue, 21 Apr 2009 19:43:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751162AbZDUXnk (ORCPT ); Tue, 21 Apr 2009 19:43:40 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:47754 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750987AbZDUXni (ORCPT ); Tue, 21 Apr 2009 19:43:38 -0400 Subject: Re: [PATCH v2] fix sign extension with 1.5TB usb-storage LBD=y From: Dave Hansen To: Matthew Wilcox Cc: linux-kernel , mdharm-usb@one-eyed-alien.net, linux-usb , usb-storage@lists.one-eyed-alien.net, James Bottomley , linux-scsi , viro In-Reply-To: <20090421230309.GC1926@parisc-linux.org> References: <1240347174.10627.20.camel@nimitz> <20090421211858.GA1926@parisc-linux.org> <1240351210.10627.30.camel@nimitz> <20090421230309.GC1926@parisc-linux.org> Content-Type: text/plain Date: Tue, 21 Apr 2009 16:43:27 -0700 Message-Id: <1240357408.10627.39.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2265 Lines: 64 Here's a patch implementing Al's suggestion. Not quite as trivial as Matthew's, but even nicer aesthetically. (Description stolen from Matthew's patch). I have verified that this fixes my issue. v3 fixed extra whitespace. -- Shifting an unsigned char implicitly casts it to a signed int. This caused 'lba' to sign-extend and Linux would then try READ CAPACITY 16 which was not supported by at least one drive. Using the get_unaligned_be*() helpers keeps us from having to worry about how the extension might occur. Signed-off-by: Dave Hansen Reviewed-by: Matthew Wilcox diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 3fcb64b..c50142b 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -50,6 +50,7 @@ #include #include #include +#include #include #include @@ -1344,12 +1345,8 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp, return -EINVAL; } - sector_size = (buffer[8] << 24) | (buffer[9] << 16) | - (buffer[10] << 8) | buffer[11]; - lba = (((u64)buffer[0] << 56) | ((u64)buffer[1] << 48) | - ((u64)buffer[2] << 40) | ((u64)buffer[3] << 32) | - ((u64)buffer[4] << 24) | ((u64)buffer[5] << 16) | - ((u64)buffer[6] << 8) | (u64)buffer[7]); + sector_size = get_unaligned_be32(&buffer[8]); + lba = get_unaligned_be64(&buffer[0]); sd_read_protection_type(sdkp, buffer); @@ -1400,10 +1397,8 @@ static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp, return -EINVAL; } - sector_size = (buffer[4] << 24) | (buffer[5] << 16) | - (buffer[6] << 8) | buffer[7]; - lba = (buffer[0] << 24) | (buffer[1] << 16) | - (buffer[2] << 8) | buffer[3]; + sector_size = get_unaligned_be32(&buffer[4]); + lba = get_unaligned_be32(&buffer[0]); if ((sizeof(sdkp->capacity) == 4) && (lba == 0xffffffff)) { sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a " -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/