#include <linux/init.h>
#include <linux/file.h>
#include <linux/blkdev.h>
-#include <linux/poll.h>
#include <linux/cdev.h>
#include <linux/jiffies.h>
#include <linux/percpu.h>
-#include <linux/uio.h>
#include <linux/idr.h>
#include <linux/bsg.h>
#include <linux/slab.h>
struct bsg_device {
struct request_queue *queue;
spinlock_t lock;
- struct list_head busy_list;
- struct list_head done_list;
struct hlist_node dev_list;
atomic_t ref_count;
- int queued_cmds;
- int done_cmds;
- wait_queue_head_t wq_done;
- wait_queue_head_t wq_free;
char name[20];
int max_queue;
- unsigned long flags;
-};
-
-enum {
- BSG_F_BLOCK = 1,
};
#define BSG_DEFAULT_CMDS 64
static struct class *bsg_class;
static int bsg_major;
-static struct kmem_cache *bsg_cmd_cachep;
-
-/*
- * our internal command type
- */
-struct bsg_command {
- struct bsg_device *bd;
- struct list_head list;
- struct request *rq;
- struct bio *bio;
- struct bio *bidi_bio;
- int err;
- struct sg_io_v4 hdr;
-};
-
-static void bsg_free_command(struct bsg_command *bc)
-{
- struct bsg_device *bd = bc->bd;
- unsigned long flags;
-
- kmem_cache_free(bsg_cmd_cachep, bc);
-
- spin_lock_irqsave(&bd->lock, flags);
- bd->queued_cmds--;
- spin_unlock_irqrestore(&bd->lock, flags);
-
- wake_up(&bd->wq_free);
-}
-
-static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
-{
- struct bsg_command *bc = ERR_PTR(-EINVAL);
-
- spin_lock_irq(&bd->lock);
-
- if (bd->queued_cmds >= bd->max_queue)
- goto out;
-
- bd->queued_cmds++;
- spin_unlock_irq(&bd->lock);
-
- bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
- if (unlikely(!bc)) {
- spin_lock_irq(&bd->lock);
- bd->queued_cmds--;
- bc = ERR_PTR(-ENOMEM);
- goto out;
- }
-
- bc->bd = bd;
- INIT_LIST_HEAD(&bc->list);
- bsg_dbg(bd, "returning free cmd %p\n", bc);
- return bc;
-out:
- spin_unlock_irq(&bd->lock);
- return bc;
-}
-
static inline struct hlist_head *bsg_dev_idx_hash(int index)
{
return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
return ERR_PTR(ret);
}
-/*
- * async completion call-back from the block layer, when scsi/ide/whatever
- * calls end_that_request_last() on a request
- */
-static void bsg_rq_end_io(struct request *rq, blk_status_t status)
-{
- struct bsg_command *bc = rq->end_io_data;
- struct bsg_device *bd = bc->bd;
- unsigned long flags;
-
- bsg_dbg(bd, "finished rq %p bc %p, bio %p\n",
- rq, bc, bc->bio);
-
- bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
-
- spin_lock_irqsave(&bd->lock, flags);
- list_move_tail(&bc->list, &bd->done_list);
- bd->done_cmds++;
- spin_unlock_irqrestore(&bd->lock, flags);
-
- wake_up(&bd->wq_done);
-}
-
-/*
- * do final setup of a 'bc' and submit the matching 'rq' to the block
- * layer for io
- */
-static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
- struct bsg_command *bc, struct request *rq)
-{
- int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
-
- /*
- * add bc command to busy queue and submit rq for io
- */
- bc->rq = rq;
- bc->bio = rq->bio;
- if (rq->next_rq)
- bc->bidi_bio = rq->next_rq->bio;
- bc->hdr.duration = jiffies;
- spin_lock_irq(&bd->lock);
- list_add_tail(&bc->list, &bd->busy_list);
- spin_unlock_irq(&bd->lock);
-
- bsg_dbg(bd, "queueing rq %p, bc %p\n", rq, bc);
-
- rq->end_io_data = bc;
- blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
-}
-
-static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
-{
- struct bsg_command *bc = NULL;
-
- spin_lock_irq(&bd->lock);
- if (bd->done_cmds) {
- bc = list_first_entry(&bd->done_list, struct bsg_command, list);
- list_del(&bc->list);
- bd->done_cmds--;
- }
- spin_unlock_irq(&bd->lock);
-
- return bc;
-}
-
-/*
- * Get a finished command from the done list
- */
-static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
-{
- struct bsg_command *bc;
- int ret;
-
- do {
- bc = bsg_next_done_cmd(bd);
- if (bc)
- break;
-
- if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
- bc = ERR_PTR(-EAGAIN);
- break;
- }
-
- ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
- if (ret) {
- bc = ERR_PTR(-ERESTARTSYS);
- break;
- }
- } while (1);
-
- bsg_dbg(bd, "returning done %p\n", bc);
-
- return bc;
-}
-
static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
struct bio *bio, struct bio *bidi_bio)
{
return ret;
}
-static bool bsg_complete(struct bsg_device *bd)
-{
- bool ret = false;
- bool spin;
-
- do {
- spin_lock_irq(&bd->lock);
-
- BUG_ON(bd->done_cmds > bd->queued_cmds);
-
- /*
- * All commands consumed.
- */
- if (bd->done_cmds == bd->queued_cmds)
- ret = true;
-
- spin = !test_bit(BSG_F_BLOCK, &bd->flags);
-
- spin_unlock_irq(&bd->lock);
- } while (!ret && spin);
-
- return ret;
-}
-
-static int bsg_complete_all_commands(struct bsg_device *bd)
-{
- struct bsg_command *bc;
- int ret, tret;
-
- bsg_dbg(bd, "entered\n");
-
- /*
- * wait for all commands to complete
- */
- io_wait_event(bd->wq_done, bsg_complete(bd));
-
- /*
- * discard done commands
- */
- ret = 0;
- do {
- spin_lock_irq(&bd->lock);
- if (!bd->queued_cmds) {
- spin_unlock_irq(&bd->lock);
- break;
- }
- spin_unlock_irq(&bd->lock);
-
- bc = bsg_get_done_cmd(bd);
- if (IS_ERR(bc))
- break;
-
- tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
- bc->bidi_bio);
- if (!ret)
- ret = tret;
-
- bsg_free_command(bc);
- } while (1);
-
- return ret;
-}
-
-static int
-__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
- const struct iovec *iov, ssize_t *bytes_read)
-{
- struct bsg_command *bc;
- int nr_commands, ret;
-
- if (count % sizeof(struct sg_io_v4))
- return -EINVAL;
-
- ret = 0;
- nr_commands = count / sizeof(struct sg_io_v4);
- while (nr_commands) {
- bc = bsg_get_done_cmd(bd);
- if (IS_ERR(bc)) {
- ret = PTR_ERR(bc);
- break;
- }
-
- /*
- * this is the only case where we need to copy data back
- * after completing the request. so do that here,
- * bsg_complete_work() cannot do that for us
- */
- ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
- bc->bidi_bio);
-
- if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
- ret = -EFAULT;
-
- bsg_free_command(bc);
-
- if (ret)
- break;
-
- buf += sizeof(struct sg_io_v4);
- *bytes_read += sizeof(struct sg_io_v4);
- nr_commands--;
- }
-
- return ret;
-}
-
-static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
-{
- if (file->f_flags & O_NONBLOCK)
- clear_bit(BSG_F_BLOCK, &bd->flags);
- else
- set_bit(BSG_F_BLOCK, &bd->flags);
-}
-
-/*
- * Check if the error is a "real" error that we should return.
- */
-static inline int err_block_err(int ret)
-{
- if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
- return 1;
-
- return 0;
-}
-
-static ssize_t
-bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
-{
- struct bsg_device *bd = file->private_data;
- int ret;
- ssize_t bytes_read;
-
- bsg_dbg(bd, "read %zd bytes\n", count);
-
- bsg_set_block(bd, file);
-
- bytes_read = 0;
- ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
- *ppos = bytes_read;
-
- if (!bytes_read || err_block_err(ret))
- bytes_read = ret;
-
- return bytes_read;
-}
-
-static int __bsg_write(struct bsg_device *bd, const char __user *buf,
- size_t count, ssize_t *bytes_written, fmode_t mode)
-{
- struct bsg_command *bc;
- struct request *rq;
- int ret, nr_commands;
-
- if (count % sizeof(struct sg_io_v4))
- return -EINVAL;
-
- nr_commands = count / sizeof(struct sg_io_v4);
- rq = NULL;
- bc = NULL;
- ret = 0;
- while (nr_commands) {
- struct request_queue *q = bd->queue;
-
- bc = bsg_alloc_command(bd);
- if (IS_ERR(bc)) {
- ret = PTR_ERR(bc);
- bc = NULL;
- break;
- }
-
- if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
- ret = -EFAULT;
- break;
- }
-
- /*
- * get a request, fill in the blanks, and add to request queue
- */
- rq = bsg_map_hdr(bd->queue, &bc->hdr, mode);
- if (IS_ERR(rq)) {
- ret = PTR_ERR(rq);
- rq = NULL;
- break;
- }
-
- bsg_add_command(bd, q, bc, rq);
- bc = NULL;
- rq = NULL;
- nr_commands--;
- buf += sizeof(struct sg_io_v4);
- *bytes_written += sizeof(struct sg_io_v4);
- }
-
- if (bc)
- bsg_free_command(bc);
-
- return ret;
-}
-
-static ssize_t
-bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
-{
- struct bsg_device *bd = file->private_data;
- ssize_t bytes_written;
- int ret;
-
- bsg_dbg(bd, "write %zd bytes\n", count);
-
- if (unlikely(uaccess_kernel()))
- return -EINVAL;
-
- bsg_set_block(bd, file);
-
- bytes_written = 0;
- ret = __bsg_write(bd, buf, count, &bytes_written, file->f_mode);
-
- *ppos = bytes_written;
-
- /*
- * return bytes written on non-fatal errors
- */
- if (!bytes_written || err_block_err(ret))
- bytes_written = ret;
-
- bsg_dbg(bd, "returning %zd\n", bytes_written);
- return bytes_written;
-}
-
static struct bsg_device *bsg_alloc_device(void)
{
struct bsg_device *bd;
return NULL;
spin_lock_init(&bd->lock);
-
bd->max_queue = BSG_DEFAULT_CMDS;
-
- INIT_LIST_HEAD(&bd->busy_list);
- INIT_LIST_HEAD(&bd->done_list);
INIT_HLIST_NODE(&bd->dev_list);
-
- init_waitqueue_head(&bd->wq_free);
- init_waitqueue_head(&bd->wq_done);
return bd;
}
static int bsg_put_device(struct bsg_device *bd)
{
- int ret = 0, do_free;
struct request_queue *q = bd->queue;
mutex_lock(&bsg_mutex);
- do_free = atomic_dec_and_test(&bd->ref_count);
- if (!do_free) {
+ if (!atomic_dec_and_test(&bd->ref_count)) {
mutex_unlock(&bsg_mutex);
- goto out;
+ return 0;
}
hlist_del(&bd->dev_list);
/*
* close can always block
*/
- set_bit(BSG_F_BLOCK, &bd->flags);
-
- /*
- * correct error detection baddies here again. it's the responsibility
- * of the app to properly reap commands before close() if it wants
- * fool-proof error detection
- */
- ret = bsg_complete_all_commands(bd);
-
kfree(bd);
-out:
- if (do_free)
- blk_put_queue(q);
- return ret;
+ blk_put_queue(q);
+ return 0;
}
static struct bsg_device *bsg_add_device(struct inode *inode,
bd->queue = rq;
- bsg_set_block(bd, file);
-
atomic_set(&bd->ref_count, 1);
hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
return bsg_put_device(bd);
}
-static __poll_t bsg_poll(struct file *file, poll_table *wait)
-{
- struct bsg_device *bd = file->private_data;
- __poll_t mask = 0;
-
- poll_wait(file, &bd->wq_done, wait);
- poll_wait(file, &bd->wq_free, wait);
-
- spin_lock_irq(&bd->lock);
- if (!list_empty(&bd->done_list))
- mask |= EPOLLIN | EPOLLRDNORM;
- if (bd->queued_cmds < bd->max_queue)
- mask |= EPOLLOUT;
- spin_unlock_irq(&bd->lock);
-
- return mask;
-}
-
static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct bsg_device *bd = file->private_data;
}
static const struct file_operations bsg_fops = {
- .read = bsg_read,
- .write = bsg_write,
- .poll = bsg_poll,
.open = bsg_open,
.release = bsg_release,
.unlocked_ioctl = bsg_ioctl,
int ret, i;
dev_t devid;
- bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
- sizeof(struct bsg_command), 0, 0, NULL);
- if (!bsg_cmd_cachep) {
- printk(KERN_ERR "bsg: failed creating slab cache\n");
- return -ENOMEM;
- }
-
for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
INIT_HLIST_HEAD(&bsg_device_list[i]);
bsg_class = class_create(THIS_MODULE, "bsg");
- if (IS_ERR(bsg_class)) {
- ret = PTR_ERR(bsg_class);
- goto destroy_kmemcache;
- }
+ if (IS_ERR(bsg_class))
+ return PTR_ERR(bsg_class);
bsg_class->devnode = bsg_devnode;
ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
destroy_bsg_class:
class_destroy(bsg_class);
-destroy_kmemcache:
- kmem_cache_destroy(bsg_cmd_cachep);
return ret;
}
projects / openwrt / staging / blogic.git / commitdiff