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[SCSI] st: get rid of scsi_tapes array
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st currently allocates an array to store pointers to all of the
scsi_tape objects. It's used to discover available indexes to use as the
base for the minor number selection and later to look up scsi_tape
devices for character devices.

We switch to using an IDR for minor selection and a pointer from
st_modedef back to scsi_tape for the lookups.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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Jeff Mahoney authored and James Bottomley committed Sep 14, 2012
1 parent e3f2a9c commit 6c648d9
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Showing 2 changed files with 70 additions and 110 deletions.
178 changes: 68 additions & 110 deletions drivers/scsi/st.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,7 @@ static const char *verstr = "20101219";
#include <linux/blkdev.h>
#include <linux/moduleparam.h>
#include <linux/cdev.h>
#include <linux/idr.h>
#include <linux/delay.h>
#include <linux/mutex.h>

Expand Down Expand Up @@ -81,9 +82,6 @@ static int try_direct_io = TRY_DIRECT_IO;
static int try_rdio = 1;
static int try_wdio = 1;

static int st_dev_max;
static int st_nr_dev;

static struct class st_sysfs_class;
static struct device_attribute st_dev_attrs[];

Expand Down Expand Up @@ -174,13 +172,9 @@ static int debugging = DEBUG;
24 bits) */
#define SET_DENS_AND_BLK 0x10001

static DEFINE_RWLOCK(st_dev_arr_lock);

static int st_fixed_buffer_size = ST_FIXED_BUFFER_SIZE;
static int st_max_sg_segs = ST_MAX_SG;

static struct scsi_tape **scsi_tapes = NULL;

static int modes_defined;

static int enlarge_buffer(struct st_buffer *, int, int);
Expand Down Expand Up @@ -222,6 +216,10 @@ static void scsi_tape_release(struct kref *);
#define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)

static DEFINE_MUTEX(st_ref_mutex);
static DEFINE_SPINLOCK(st_index_lock);
static DEFINE_SPINLOCK(st_use_lock);
static DEFINE_IDR(st_index_idr);



#include "osst_detect.h"
Expand All @@ -239,10 +237,9 @@ static struct scsi_tape *scsi_tape_get(int dev)
struct scsi_tape *STp = NULL;

mutex_lock(&st_ref_mutex);
write_lock(&st_dev_arr_lock);
spin_lock(&st_index_lock);

if (dev < st_dev_max && scsi_tapes != NULL)
STp = scsi_tapes[dev];
STp = idr_find(&st_index_idr, dev);
if (!STp) goto out;

kref_get(&STp->kref);
Expand All @@ -259,7 +256,7 @@ static struct scsi_tape *scsi_tape_get(int dev)
kref_put(&STp->kref, scsi_tape_release);
STp = NULL;
out:
write_unlock(&st_dev_arr_lock);
spin_unlock(&st_index_lock);
mutex_unlock(&st_ref_mutex);
return STp;
}
Expand Down Expand Up @@ -1202,20 +1199,20 @@ static int st_open(struct inode *inode, struct file *filp)
return -ENXIO;
}

write_lock(&st_dev_arr_lock);
filp->private_data = STp;
name = tape_name(STp);

spin_lock(&st_use_lock);
if (STp->in_use) {
write_unlock(&st_dev_arr_lock);
spin_unlock(&st_use_lock);
scsi_tape_put(STp);
mutex_unlock(&st_mutex);
DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
return (-EBUSY);
}

STp->in_use = 1;
write_unlock(&st_dev_arr_lock);
spin_unlock(&st_use_lock);
STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;

if (scsi_autopm_get_device(STp->device) < 0) {
Expand Down Expand Up @@ -1404,9 +1401,9 @@ static int st_release(struct inode *inode, struct file *filp)
do_door_lock(STp, 0);

normalize_buffer(STp->buffer);
write_lock(&st_dev_arr_lock);
spin_lock(&st_use_lock);
STp->in_use = 0;
write_unlock(&st_dev_arr_lock);
spin_unlock(&st_use_lock);
scsi_autopm_put_device(STp->device);
scsi_tape_put(STp);

Expand Down Expand Up @@ -4029,58 +4026,16 @@ static int st_probe(struct device *dev)
goto out_buffer_free;
}

write_lock(&st_dev_arr_lock);
if (st_nr_dev >= st_dev_max) {
struct scsi_tape **tmp_da;
int tmp_dev_max;

tmp_dev_max = max(st_nr_dev * 2, 8);
if (tmp_dev_max > ST_MAX_TAPES)
tmp_dev_max = ST_MAX_TAPES;
if (tmp_dev_max <= st_nr_dev) {
write_unlock(&st_dev_arr_lock);
printk(KERN_ERR "st: Too many tape devices (max. %d).\n",
ST_MAX_TAPES);
goto out_put_disk;
}

tmp_da = kzalloc(tmp_dev_max * sizeof(struct scsi_tape *), GFP_ATOMIC);
if (tmp_da == NULL) {
write_unlock(&st_dev_arr_lock);
printk(KERN_ERR "st: Can't extend device array.\n");
goto out_put_disk;
}

if (scsi_tapes != NULL) {
memcpy(tmp_da, scsi_tapes,
st_dev_max * sizeof(struct scsi_tape *));
kfree(scsi_tapes);
}
scsi_tapes = tmp_da;

st_dev_max = tmp_dev_max;
}

for (i = 0; i < st_dev_max; i++)
if (scsi_tapes[i] == NULL)
break;
if (i >= st_dev_max)
panic("scsi_devices corrupt (st)");

tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
if (tpnt == NULL) {
write_unlock(&st_dev_arr_lock);
printk(KERN_ERR "st: Can't allocate device descriptor.\n");
goto out_put_disk;
}
kref_init(&tpnt->kref);
tpnt->disk = disk;
sprintf(disk->disk_name, "st%d", i);
disk->private_data = &tpnt->driver;
disk->queue = SDp->request_queue;
tpnt->driver = &st_template;
scsi_tapes[i] = tpnt;
dev_num = i;

tpnt->device = SDp;
if (SDp->scsi_level <= 2)
Expand Down Expand Up @@ -4126,6 +4081,7 @@ static int st_probe(struct device *dev)
STm->default_compression = ST_DONT_TOUCH;
STm->default_blksize = (-1); /* No forced size */
STm->default_density = (-1); /* No forced density */
STm->tape = tpnt;
}

for (i = 0; i < ST_NBR_PARTITIONS; i++) {
Expand All @@ -4145,8 +4101,29 @@ static int st_probe(struct device *dev)
tpnt->blksize_changed = 0;
mutex_init(&tpnt->lock);

st_nr_dev++;
write_unlock(&st_dev_arr_lock);
if (!idr_pre_get(&st_index_idr, GFP_KERNEL)) {
pr_warn("st: idr expansion failed\n");
error = -ENOMEM;
goto out_put_disk;
}

spin_lock(&st_index_lock);
error = idr_get_new(&st_index_idr, tpnt, &dev_num);
spin_unlock(&st_index_lock);
if (error) {
pr_warn("st: idr allocation failed: %d\n", error);
goto out_put_disk;
}

if (dev_num > ST_MAX_TAPES) {
pr_err("st: Too many tape devices (max. %d).\n", ST_MAX_TAPES);
goto out_put_index;
}

tpnt->index = dev_num;
sprintf(disk->disk_name, "st%d", dev_num);

dev_set_drvdata(dev, tpnt);

for (mode = 0; mode < ST_NBR_MODES; ++mode) {
STm = &(tpnt->modes[mode]);
Expand Down Expand Up @@ -4189,10 +4166,10 @@ static int st_probe(struct device *dev)
return 0;

out_free_tape:
sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
"tape");
for (mode=0; mode < ST_NBR_MODES; mode++) {
STm = &(tpnt->modes[mode]);
sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
"tape");
for (j=0; j < 2; j++) {
if (STm->cdevs[j]) {
device_destroy(&st_sysfs_class,
Expand All @@ -4202,10 +4179,10 @@ static int st_probe(struct device *dev)
}
}
}
write_lock(&st_dev_arr_lock);
scsi_tapes[dev_num] = NULL;
st_nr_dev--;
write_unlock(&st_dev_arr_lock);
out_put_index:
spin_lock(&st_index_lock);
idr_remove(&st_index_idr, dev_num);
spin_unlock(&st_index_lock);
out_put_disk:
put_disk(disk);
kfree(tpnt);
Expand All @@ -4218,38 +4195,32 @@ static int st_probe(struct device *dev)

static int st_remove(struct device *dev)
{
struct scsi_device *SDp = to_scsi_device(dev);
struct scsi_tape *tpnt;
int i, j, mode;

scsi_autopm_get_device(SDp);
write_lock(&st_dev_arr_lock);
for (i = 0; i < st_dev_max; i++) {
tpnt = scsi_tapes[i];
if (tpnt != NULL && tpnt->device == SDp) {
scsi_tapes[i] = NULL;
st_nr_dev--;
write_unlock(&st_dev_arr_lock);
sysfs_remove_link(&tpnt->device->sdev_gendev.kobj,
"tape");
for (mode = 0; mode < ST_NBR_MODES; ++mode) {
for (j=0; j < 2; j++) {
device_destroy(&st_sysfs_class,
MKDEV(SCSI_TAPE_MAJOR,
TAPE_MINOR(i, mode, j)));
cdev_del(tpnt->modes[mode].cdevs[j]);
tpnt->modes[mode].cdevs[j] = NULL;
}
}

mutex_lock(&st_ref_mutex);
kref_put(&tpnt->kref, scsi_tape_release);
mutex_unlock(&st_ref_mutex);
return 0;
struct scsi_tape *tpnt = dev_get_drvdata(dev);
int rew, mode;
dev_t cdev_devno;
struct cdev *cdev;
int index = tpnt->index;

scsi_autopm_get_device(to_scsi_device(dev));
sysfs_remove_link(&tpnt->device->sdev_gendev.kobj, "tape");
for (mode = 0; mode < ST_NBR_MODES; ++mode) {
for (rew = 0; rew < 2; rew++) {
cdev = tpnt->modes[mode].cdevs[rew];
if (!cdev)
continue;
cdev_devno = cdev->dev;
device_destroy(&st_sysfs_class, cdev_devno);
cdev_del(tpnt->modes[mode].cdevs[rew]);
tpnt->modes[mode].cdevs[rew] = NULL;
}
}

write_unlock(&st_dev_arr_lock);
mutex_lock(&st_ref_mutex);
kref_put(&tpnt->kref, scsi_tape_release);
mutex_unlock(&st_ref_mutex);
spin_lock(&st_index_lock);
idr_remove(&st_index_idr, index);
spin_unlock(&st_index_lock);
return 0;
}

Expand Down Expand Up @@ -4336,7 +4307,6 @@ static void __exit exit_st(void)
unregister_chrdev_region(MKDEV(SCSI_TAPE_MAJOR, 0),
ST_MAX_TAPE_ENTRIES);
class_unregister(&st_sysfs_class);
kfree(scsi_tapes);
printk(KERN_INFO "st: Unloaded.\n");
}

Expand Down Expand Up @@ -4459,22 +4429,10 @@ static ssize_t
options_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct st_modedef *STm = dev_get_drvdata(dev);
struct scsi_tape *STp;
int i, j, options;
struct scsi_tape *STp = STm->tape;
int options;
ssize_t l = 0;

for (i=0; i < st_dev_max; i++) {
for (j=0; j < ST_NBR_MODES; j++)
if (&scsi_tapes[i]->modes[j] == STm)
break;
if (j < ST_NBR_MODES)
break;
}
if (i == st_dev_max)
return 0; /* should never happen */

STp = scsi_tapes[i];

options = STm->do_buffer_writes ? MT_ST_BUFFER_WRITES : 0;
options |= STm->do_async_writes ? MT_ST_ASYNC_WRITES : 0;
options |= STm->do_read_ahead ? MT_ST_READ_AHEAD : 0;
Expand Down
2 changes: 2 additions & 0 deletions drivers/scsi/st.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ struct st_modedef {
unsigned char default_compression; /* 0 = don't touch, etc */
short default_density; /* Forced density, -1 = no value */
int default_blksize; /* Forced blocksize, -1 = no value */
struct scsi_tape *tape;
struct cdev *cdevs[2]; /* Auto-rewind and non-rewind devices */
};

Expand Down Expand Up @@ -99,6 +100,7 @@ struct scsi_tape {
struct mutex lock; /* For serialization */
struct completion wait; /* For SCSI commands */
struct st_buffer *buffer;
int index;

/* Drive characteristics */
unsigned char omit_blklims;
Expand Down

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