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linux/arch/ia64/hp/sim/simscsi.c
Jeff Garzik f281233d3e SCSI host lock push-down 
Move the mid-layer's ->queuecommand() invocation from being locked
with the host lock to being unlocked to facilitate speeding up the
critical path for drivers who don't need this lock taken anyway.

The patch below presents a simple SCSI host lock push-down as an
equivalent transformation.  No locking or other behavior should change
with this patch.  All existing bugs and locking orders are preserved.

Additionally, add one parameter to queuecommand,
	struct Scsi_Host *
and remove one parameter from queuecommand,
	void (*done)(struct scsi_cmnd *)

Scsi_Host* is a convenient pointer that most host drivers need anyway,
and 'done' is redundant to struct scsi_cmnd->scsi_done.

Minimal code disturbance was attempted with this change.  Most drivers
needed only two one-line modifications for their host lock push-down.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Acked-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-16 13:33:23 -08:00

381 lines
8.7 KiB
C
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/*
* Simulated SCSI driver.
*
* Copyright (C) 1999, 2001-2003 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
* Stephane Eranian <eranian@hpl.hp.com>
*
* 02/01/15 David Mosberger Updated for v2.5.1
* 99/12/18 David Mosberger Added support for READ10/WRITE10 needed by linux v2.3.33
*/
#include <linux/blkdev.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <asm/irq.h>
#include "hpsim_ssc.h"
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#define DEBUG_SIMSCSI 0
#define SIMSCSI_REQ_QUEUE_LEN 64
#define DEFAULT_SIMSCSI_ROOT "/var/ski-disks/sd"
/* Simulator system calls: */
#define SSC_OPEN 50
#define SSC_CLOSE 51
#define SSC_READ 52
#define SSC_WRITE 53
#define SSC_GET_COMPLETION 54
#define SSC_WAIT_COMPLETION 55
#define SSC_WRITE_ACCESS 2
#define SSC_READ_ACCESS 1
#if DEBUG_SIMSCSI
int simscsi_debug;
# define DBG simscsi_debug
#else
# define DBG 0
#endif
static struct Scsi_Host *host;
static void simscsi_interrupt (unsigned long val);
static DECLARE_TASKLET(simscsi_tasklet, simscsi_interrupt, 0);
struct disk_req {
unsigned long addr;
unsigned len;
};
struct disk_stat {
int fd;
unsigned count;
};
static int desc[16] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
};
static struct queue_entry {
struct scsi_cmnd *sc;
} queue[SIMSCSI_REQ_QUEUE_LEN];
static int rd, wr;
static atomic_t num_reqs = ATOMIC_INIT(0);
/* base name for default disks */
static char *simscsi_root = DEFAULT_SIMSCSI_ROOT;
#define MAX_ROOT_LEN 128
/*
* used to setup a new base for disk images
* to use /foo/bar/disk[a-z] as disk images
* you have to specify simscsi=/foo/bar/disk on the command line
*/
static int __init
simscsi_setup (char *s)
{
/* XXX Fix me we may need to strcpy() ? */
if (strlen(s) > MAX_ROOT_LEN) {
printk(KERN_ERR "simscsi_setup: prefix too long---using default %s\n",
simscsi_root);
}
simscsi_root = s;
return 1;
}
__setup("simscsi=", simscsi_setup);
static void
simscsi_interrupt (unsigned long val)
{
struct scsi_cmnd *sc;
while ((sc = queue[rd].sc) != NULL) {
atomic_dec(&num_reqs);
queue[rd].sc = NULL;
if (DBG)
printk("simscsi_interrupt: done with %ld\n", sc->serial_number);
(*sc->scsi_done)(sc);
rd = (rd + 1) % SIMSCSI_REQ_QUEUE_LEN;
}
}
static int
simscsi_biosparam (struct scsi_device *sdev, struct block_device *n,
sector_t capacity, int ip[])
{
ip[0] = 64; /* heads */
ip[1] = 32; /* sectors */
ip[2] = capacity >> 11; /* cylinders */
return 0;
}
static void
simscsi_sg_readwrite (struct scsi_cmnd *sc, int mode, unsigned long offset)
{
int i;
struct scatterlist *sl;
struct disk_stat stat;
struct disk_req req;
stat.fd = desc[sc->device->id];
scsi_for_each_sg(sc, sl, scsi_sg_count(sc), i) {
req.addr = __pa(sg_virt(sl));
req.len = sl->length;
if (DBG)
printk("simscsi_sg_%s @ %lx (off %lx) use_sg=%d len=%d\n",
mode == SSC_READ ? "read":"write", req.addr, offset,
scsi_sg_count(sc) - i, sl->length);
ia64_ssc(stat.fd, 1, __pa(&req), offset, mode);
ia64_ssc(__pa(&stat), 0, 0, 0, SSC_WAIT_COMPLETION);
/* should not happen in our case */
if (stat.count != req.len) {
sc->result = DID_ERROR << 16;
return;
}
offset += sl->length;
}
sc->result = GOOD;
}
/*
* function handling both READ_6/WRITE_6 (non-scatter/gather mode)
* commands.
* Added 02/26/99 S.Eranian
*/
static void
simscsi_readwrite6 (struct scsi_cmnd *sc, int mode)
{
unsigned long offset;
offset = (((sc->cmnd[1] & 0x1f) << 16) | (sc->cmnd[2] << 8) | sc->cmnd[3])*512;
simscsi_sg_readwrite(sc, mode, offset);
}
static size_t
simscsi_get_disk_size (int fd)
{
struct disk_stat stat;
size_t bit, sectors = 0;
struct disk_req req;
char buf[512];
/*
* This is a bit kludgey: the simulator doesn't provide a
* direct way of determining the disk size, so we do a binary
* search, assuming a maximum disk size of 128GB.
*/
for (bit = (128UL << 30)/512; bit != 0; bit >>= 1) {
req.addr = __pa(&buf);
req.len = sizeof(buf);
ia64_ssc(fd, 1, __pa(&req), ((sectors | bit) - 1)*512, SSC_READ);
stat.fd = fd;
ia64_ssc(__pa(&stat), 0, 0, 0, SSC_WAIT_COMPLETION);
if (stat.count == sizeof(buf))
sectors |= bit;
}
return sectors - 1; /* return last valid sector number */
}
static void
simscsi_readwrite10 (struct scsi_cmnd *sc, int mode)
{
unsigned long offset;
offset = (((unsigned long)sc->cmnd[2] << 24)
| ((unsigned long)sc->cmnd[3] << 16)
| ((unsigned long)sc->cmnd[4] << 8)
| ((unsigned long)sc->cmnd[5] << 0))*512UL;
simscsi_sg_readwrite(sc, mode, offset);
}
static int
simscsi_queuecommand_lck (struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
{
unsigned int target_id = sc->device->id;
char fname[MAX_ROOT_LEN+16];
size_t disk_size;
char *buf;
char localbuf[36];
#if DEBUG_SIMSCSI
register long sp asm ("sp");
if (DBG)
printk("simscsi_queuecommand: target=%d,cmnd=%u,sc=%lu,sp=%lx,done=%p\n",
target_id, sc->cmnd[0], sc->serial_number, sp, done);
#endif
sc->result = DID_BAD_TARGET << 16;
sc->scsi_done = done;
if (target_id <= 15 && sc->device->lun == 0) {
switch (sc->cmnd[0]) {
case INQUIRY:
if (scsi_bufflen(sc) < 35) {
break;
}
sprintf (fname, "%s%c", simscsi_root, 'a' + target_id);
desc[target_id] = ia64_ssc(__pa(fname), SSC_READ_ACCESS|SSC_WRITE_ACCESS,
0, 0, SSC_OPEN);
if (desc[target_id] < 0) {
/* disk doesn't exist... */
break;
}
buf = localbuf;
buf[0] = 0; /* magnetic disk */
buf[1] = 0; /* not a removable medium */
buf[2] = 2; /* SCSI-2 compliant device */
buf[3] = 2; /* SCSI-2 response data format */
buf[4] = 31; /* additional length (bytes) */
buf[5] = 0; /* reserved */
buf[6] = 0; /* reserved */
buf[7] = 0; /* various flags */
memcpy(buf + 8, "HP SIMULATED DISK 0.00", 28);
scsi_sg_copy_from_buffer(sc, buf, 36);
sc->result = GOOD;
break;
case TEST_UNIT_READY:
sc->result = GOOD;
break;
case READ_6:
if (desc[target_id] < 0 )
break;
simscsi_readwrite6(sc, SSC_READ);
break;
case READ_10:
if (desc[target_id] < 0 )
break;
simscsi_readwrite10(sc, SSC_READ);
break;
case WRITE_6:
if (desc[target_id] < 0)
break;
simscsi_readwrite6(sc, SSC_WRITE);
break;
case WRITE_10:
if (desc[target_id] < 0)
break;
simscsi_readwrite10(sc, SSC_WRITE);
break;
case READ_CAPACITY:
if (desc[target_id] < 0 || scsi_bufflen(sc) < 8) {
break;
}
buf = localbuf;
disk_size = simscsi_get_disk_size(desc[target_id]);
buf[0] = (disk_size >> 24) & 0xff;
buf[1] = (disk_size >> 16) & 0xff;
buf[2] = (disk_size >> 8) & 0xff;
buf[3] = (disk_size >> 0) & 0xff;
/* set block size of 512 bytes: */
buf[4] = 0;
buf[5] = 0;
buf[6] = 2;
buf[7] = 0;
scsi_sg_copy_from_buffer(sc, buf, 8);
sc->result = GOOD;
break;
case MODE_SENSE:
case MODE_SENSE_10:
/* sd.c uses this to determine whether disk does write-caching. */
scsi_sg_copy_from_buffer(sc, (char *)empty_zero_page,
PAGE_SIZE);
sc->result = GOOD;
break;
case START_STOP:
printk(KERN_ERR "START_STOP\n");
break;
default:
panic("simscsi: unknown SCSI command %u\n", sc->cmnd[0]);
}
}
if (sc->result == DID_BAD_TARGET) {
sc->result |= DRIVER_SENSE << 24;
sc->sense_buffer[0] = 0x70;
sc->sense_buffer[2] = 0x00;
}
if (atomic_read(&num_reqs) >= SIMSCSI_REQ_QUEUE_LEN) {
panic("Attempt to queue command while command is pending!!");
}
atomic_inc(&num_reqs);
queue[wr].sc = sc;
wr = (wr + 1) % SIMSCSI_REQ_QUEUE_LEN;
tasklet_schedule(&simscsi_tasklet);
return 0;
}
static DEF_SCSI_QCMD(simscsi_queuecommand)
static int
simscsi_host_reset (struct scsi_cmnd *sc)
{
printk(KERN_ERR "simscsi_host_reset: not implemented\n");
return 0;
}
static struct scsi_host_template driver_template = {
.name = "simulated SCSI host adapter",
.proc_name = "simscsi",
.queuecommand = simscsi_queuecommand,
.eh_host_reset_handler = simscsi_host_reset,
.bios_param = simscsi_biosparam,
.can_queue = SIMSCSI_REQ_QUEUE_LEN,
.this_id = -1,
.sg_tablesize = SG_ALL,
.max_sectors = 1024,
.cmd_per_lun = SIMSCSI_REQ_QUEUE_LEN,
.use_clustering = DISABLE_CLUSTERING,
};
static int __init
simscsi_init(void)
{
int error;
host = scsi_host_alloc(&driver_template, 0);
if (!host)
return -ENOMEM;
error = scsi_add_host(host, NULL);
if (error)
goto free_host;
scsi_scan_host(host);
return 0;
free_host:
scsi_host_put(host);
return error;
}
static void __exit
simscsi_exit(void)
{
scsi_remove_host(host);
scsi_host_put(host);
}
module_init(simscsi_init);
module_exit(simscsi_exit);
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