kernel-ark/drivers/usb/storage/scsiglue.c
Matthew Dharm 226173edae [PATCH] USB: storage: Fix messed-up locking
This is patch as550 from Alan Stern.

Apparently someone changed the SCSI core so that it no longer holds the
host lock when doing a device or bus reset.  usb-storage was updated at
the time, but the change was done carelessly.  Some of the code depends
on that lock being held.

This patch reintroduces the host lock where needed and tries to clarify
the comments explaining why the lock is necessary.  It also moves the
code that clears the TIMED_OUT and ABORTING bitflags so that it executes
as soon as the timed-out command has completed (and while the host lock
is held).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-09-12 12:23:50 -07:00

488 lines
15 KiB
C

/* Driver for USB Mass Storage compliant devices
* SCSI layer glue code
*
* $Id: scsiglue.c,v 1.26 2002/04/22 03:39:43 mdharm Exp $
*
* Current development and maintenance by:
* (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
*
* Developed with the assistance of:
* (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
* (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
*
* Initial work by:
* (c) 1999 Michael Gee (michael@linuxspecific.com)
*
* This driver is based on the 'USB Mass Storage Class' document. This
* describes in detail the protocol used to communicate with such
* devices. Clearly, the designers had SCSI and ATAPI commands in
* mind when they created this document. The commands are all very
* similar to commands in the SCSI-II and ATAPI specifications.
*
* It is important to note that in a number of cases this class
* exhibits class-specific exemptions from the USB specification.
* Notably the usage of NAK, STALL and ACK differs from the norm, in
* that they are used to communicate wait, failed and OK on commands.
*
* Also, for certain devices, the interrupt endpoint is used to convey
* status of a command.
*
* Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
* information about this driver.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_devinfo.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include "usb.h"
#include "scsiglue.h"
#include "debug.h"
#include "transport.h"
#include "protocol.h"
/***********************************************************************
* Host functions
***********************************************************************/
static const char* host_info(struct Scsi_Host *host)
{
return "SCSI emulation for USB Mass Storage devices";
}
static int slave_alloc (struct scsi_device *sdev)
{
/*
* Set the INQUIRY transfer length to 36. We don't use any of
* the extra data and many devices choke if asked for more or
* less than 36 bytes.
*/
sdev->inquiry_len = 36;
return 0;
}
static int slave_configure(struct scsi_device *sdev)
{
struct us_data *us = host_to_us(sdev->host);
/* Scatter-gather buffers (all but the last) must have a length
* divisible by the bulk maxpacket size. Otherwise a data packet
* would end up being short, causing a premature end to the data
* transfer. Since high-speed bulk pipes have a maxpacket size
* of 512, we'll use that as the scsi device queue's DMA alignment
* mask. Guaranteeing proper alignment of the first buffer will
* have the desired effect because, except at the beginning and
* the end, scatter-gather buffers follow page boundaries. */
blk_queue_dma_alignment(sdev->request_queue, (512 - 1));
/* Set the SCSI level to at least 2. We'll leave it at 3 if that's
* what is originally reported. We need this to avoid confusing
* the SCSI layer with devices that report 0 or 1, but need 10-byte
* commands (ala ATAPI devices behind certain bridges, or devices
* which simply have broken INQUIRY data).
*
* NOTE: This means /dev/sg programs (ala cdrecord) will get the
* actual information. This seems to be the preference for
* programs like that.
*
* NOTE: This also means that /proc/scsi/scsi and sysfs may report
* the actual value or the modified one, depending on where the
* data comes from.
*/
if (sdev->scsi_level < SCSI_2)
sdev->scsi_level = SCSI_2;
/* According to the technical support people at Genesys Logic,
* devices using their chips have problems transferring more than
* 32 KB at a time. In practice people have found that 64 KB
* works okay and that's what Windows does. But we'll be
* conservative; people can always use the sysfs interface to
* increase max_sectors. */
if (le16_to_cpu(us->pusb_dev->descriptor.idVendor) == USB_VENDOR_ID_GENESYS &&
sdev->request_queue->max_sectors > 64)
blk_queue_max_sectors(sdev->request_queue, 64);
/* We can't put these settings in slave_alloc() because that gets
* called before the device type is known. Consequently these
* settings can't be overridden via the scsi devinfo mechanism. */
if (sdev->type == TYPE_DISK) {
/* Disk-type devices use MODE SENSE(6) if the protocol
* (SubClass) is Transparent SCSI, otherwise they use
* MODE SENSE(10). */
if (us->subclass != US_SC_SCSI)
sdev->use_10_for_ms = 1;
/* Many disks only accept MODE SENSE transfer lengths of
* 192 bytes (that's what Windows uses). */
sdev->use_192_bytes_for_3f = 1;
/* Some devices don't like MODE SENSE with page=0x3f,
* which is the command used for checking if a device
* is write-protected. Now that we tell the sd driver
* to do a 192-byte transfer with this command the
* majority of devices work fine, but a few still can't
* handle it. The sd driver will simply assume those
* devices are write-enabled. */
if (us->flags & US_FL_NO_WP_DETECT)
sdev->skip_ms_page_3f = 1;
/* A number of devices have problems with MODE SENSE for
* page x08, so we will skip it. */
sdev->skip_ms_page_8 = 1;
/* Some disks return the total number of blocks in response
* to READ CAPACITY rather than the highest block number.
* If this device makes that mistake, tell the sd driver. */
if (us->flags & US_FL_FIX_CAPACITY)
sdev->fix_capacity = 1;
/* Some devices report a SCSI revision level above 2 but are
* unable to handle the REPORT LUNS command (for which
* support is mandatory at level 3). Since we already have
* a Get-Max-LUN request, we won't lose much by setting the
* revision level down to 2. The only devices that would be
* affected are those with sparse LUNs. */
sdev->scsi_level = SCSI_2;
/* USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
* Hardware Error) when any low-level error occurs,
* recoverable or not. Setting this flag tells the SCSI
* midlayer to retry such commands, which frequently will
* succeed and fix the error. The worst this can lead to
* is an occasional series of retries that will all fail. */
sdev->retry_hwerror = 1;
} else {
/* Non-disk-type devices don't need to blacklist any pages
* or to force 192-byte transfer lengths for MODE SENSE.
* But they do need to use MODE SENSE(10). */
sdev->use_10_for_ms = 1;
}
/* Some devices choke when they receive a PREVENT-ALLOW MEDIUM
* REMOVAL command, so suppress those commands. */
if (us->flags & US_FL_NOT_LOCKABLE)
sdev->lockable = 0;
/* this is to satisfy the compiler, tho I don't think the
* return code is ever checked anywhere. */
return 0;
}
/* queue a command */
/* This is always called with scsi_lock(host) held */
static int queuecommand(struct scsi_cmnd *srb,
void (*done)(struct scsi_cmnd *))
{
struct us_data *us = host_to_us(srb->device->host);
US_DEBUGP("%s called\n", __FUNCTION__);
/* check for state-transition errors */
if (us->srb != NULL) {
printk(KERN_ERR USB_STORAGE "Error in %s: us->srb = %p\n",
__FUNCTION__, us->srb);
return SCSI_MLQUEUE_HOST_BUSY;
}
/* fail the command if we are disconnecting */
if (test_bit(US_FLIDX_DISCONNECTING, &us->flags)) {
US_DEBUGP("Fail command during disconnect\n");
srb->result = DID_NO_CONNECT << 16;
done(srb);
return 0;
}
/* enqueue the command and wake up the control thread */
srb->scsi_done = done;
us->srb = srb;
up(&(us->sema));
return 0;
}
/***********************************************************************
* Error handling functions
***********************************************************************/
/* Command timeout and abort */
static int command_abort(struct scsi_cmnd *srb)
{
struct us_data *us = host_to_us(srb->device->host);
US_DEBUGP("%s called\n", __FUNCTION__);
/* us->srb together with the TIMED_OUT, RESETTING, and ABORTING
* bits are protected by the host lock. */
scsi_lock(us_to_host(us));
/* Is this command still active? */
if (us->srb != srb) {
scsi_unlock(us_to_host(us));
US_DEBUGP ("-- nothing to abort\n");
return FAILED;
}
/* Set the TIMED_OUT bit. Also set the ABORTING bit, but only if
* a device reset isn't already in progress (to avoid interfering
* with the reset). Note that we must retain the host lock while
* calling usb_stor_stop_transport(); otherwise it might interfere
* with an auto-reset that begins as soon as we release the lock. */
set_bit(US_FLIDX_TIMED_OUT, &us->flags);
if (!test_bit(US_FLIDX_RESETTING, &us->flags)) {
set_bit(US_FLIDX_ABORTING, &us->flags);
usb_stor_stop_transport(us);
}
scsi_unlock(us_to_host(us));
/* Wait for the aborted command to finish */
wait_for_completion(&us->notify);
return SUCCESS;
}
/* This invokes the transport reset mechanism to reset the state of the
* device */
static int device_reset(struct scsi_cmnd *srb)
{
struct us_data *us = host_to_us(srb->device->host);
int result;
US_DEBUGP("%s called\n", __FUNCTION__);
/* lock the device pointers and do the reset */
down(&(us->dev_semaphore));
result = us->transport_reset(us);
up(&(us->dev_semaphore));
return result < 0 ? FAILED : SUCCESS;
}
/* Simulate a SCSI bus reset by resetting the device's USB port. */
static int bus_reset(struct scsi_cmnd *srb)
{
struct us_data *us = host_to_us(srb->device->host);
int result;
US_DEBUGP("%s called\n", __FUNCTION__);
down(&(us->dev_semaphore));
result = usb_stor_port_reset(us);
up(&(us->dev_semaphore));
return result < 0 ? FAILED : SUCCESS;
}
/* Report a driver-initiated device reset to the SCSI layer.
* Calling this for a SCSI-initiated reset is unnecessary but harmless.
* The caller must own the SCSI host lock. */
void usb_stor_report_device_reset(struct us_data *us)
{
int i;
struct Scsi_Host *host = us_to_host(us);
scsi_report_device_reset(host, 0, 0);
if (us->flags & US_FL_SCM_MULT_TARG) {
for (i = 1; i < host->max_id; ++i)
scsi_report_device_reset(host, 0, i);
}
}
/* Report a driver-initiated bus reset to the SCSI layer.
* Calling this for a SCSI-initiated reset is unnecessary but harmless.
* The caller must own the SCSI host lock. */
void usb_stor_report_bus_reset(struct us_data *us)
{
scsi_report_bus_reset(us_to_host(us), 0);
}
/***********************************************************************
* /proc/scsi/ functions
***********************************************************************/
/* we use this macro to help us write into the buffer */
#undef SPRINTF
#define SPRINTF(args...) \
do { if (pos < buffer+length) pos += sprintf(pos, ## args); } while (0)
static int proc_info (struct Scsi_Host *host, char *buffer,
char **start, off_t offset, int length, int inout)
{
struct us_data *us = host_to_us(host);
char *pos = buffer;
const char *string;
/* if someone is sending us data, just throw it away */
if (inout)
return length;
/* print the controller name */
SPRINTF(" Host scsi%d: usb-storage\n", host->host_no);
/* print product, vendor, and serial number strings */
if (us->pusb_dev->manufacturer)
string = us->pusb_dev->manufacturer;
else if (us->unusual_dev->vendorName)
string = us->unusual_dev->vendorName;
else
string = "Unknown";
SPRINTF(" Vendor: %s\n", string);
if (us->pusb_dev->product)
string = us->pusb_dev->product;
else if (us->unusual_dev->productName)
string = us->unusual_dev->productName;
else
string = "Unknown";
SPRINTF(" Product: %s\n", string);
if (us->pusb_dev->serial)
string = us->pusb_dev->serial;
else
string = "None";
SPRINTF("Serial Number: %s\n", string);
/* show the protocol and transport */
SPRINTF(" Protocol: %s\n", us->protocol_name);
SPRINTF(" Transport: %s\n", us->transport_name);
/* show the device flags */
if (pos < buffer + length) {
pos += sprintf(pos, " Quirks:");
#define US_FLAG(name, value) \
if (us->flags & value) pos += sprintf(pos, " " #name);
US_DO_ALL_FLAGS
#undef US_FLAG
*(pos++) = '\n';
}
/*
* Calculate start of next buffer, and return value.
*/
*start = buffer + offset;
if ((pos - buffer) < offset)
return (0);
else if ((pos - buffer - offset) < length)
return (pos - buffer - offset);
else
return (length);
}
/***********************************************************************
* Sysfs interface
***********************************************************************/
/* Output routine for the sysfs max_sectors file */
static ssize_t show_max_sectors(struct device *dev, struct device_attribute *attr, char *buf)
{
struct scsi_device *sdev = to_scsi_device(dev);
return sprintf(buf, "%u\n", sdev->request_queue->max_sectors);
}
/* Input routine for the sysfs max_sectors file */
static ssize_t store_max_sectors(struct device *dev, struct device_attribute *attr, const char *buf,
size_t count)
{
struct scsi_device *sdev = to_scsi_device(dev);
unsigned short ms;
if (sscanf(buf, "%hu", &ms) > 0 && ms <= SCSI_DEFAULT_MAX_SECTORS) {
blk_queue_max_sectors(sdev->request_queue, ms);
return strlen(buf);
}
return -EINVAL;
}
static DEVICE_ATTR(max_sectors, S_IRUGO | S_IWUSR, show_max_sectors,
store_max_sectors);
static struct device_attribute *sysfs_device_attr_list[] = {
&dev_attr_max_sectors,
NULL,
};
/*
* this defines our host template, with which we'll allocate hosts
*/
struct scsi_host_template usb_stor_host_template = {
/* basic userland interface stuff */
.name = "usb-storage",
.proc_name = "usb-storage",
.proc_info = proc_info,
.info = host_info,
/* command interface -- queued only */
.queuecommand = queuecommand,
/* error and abort handlers */
.eh_abort_handler = command_abort,
.eh_device_reset_handler = device_reset,
.eh_bus_reset_handler = bus_reset,
/* queue commands only, only one command per LUN */
.can_queue = 1,
.cmd_per_lun = 1,
/* unknown initiator id */
.this_id = -1,
.slave_alloc = slave_alloc,
.slave_configure = slave_configure,
/* lots of sg segments can be handled */
.sg_tablesize = SG_ALL,
/* limit the total size of a transfer to 120 KB */
.max_sectors = 240,
/* merge commands... this seems to help performance, but
* periodically someone should test to see which setting is more
* optimal.
*/
.use_clustering = 1,
/* emulated HBA */
.emulated = 1,
/* we do our own delay after a device or bus reset */
.skip_settle_delay = 1,
/* sysfs device attributes */
.sdev_attrs = sysfs_device_attr_list,
/* module management */
.module = THIS_MODULE
};
/* To Report "Illegal Request: Invalid Field in CDB */
unsigned char usb_stor_sense_invalidCDB[18] = {
[0] = 0x70, /* current error */
[2] = ILLEGAL_REQUEST, /* Illegal Request = 0x05 */
[7] = 0x0a, /* additional length */
[12] = 0x24 /* Invalid Field in CDB */
};