Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 *

 */

#include <linux/kernel.h>

#include <linux/blkdev.h>

#include <linux/blktrace_api.h>

#include <linux/percpu.h>

#include <linux/init.h>

#include <linux/mutex.h>

#include <linux/debugfs.h>

#include <linux/time.h>

#include <asm/uaccess.h>

static unsigned int blktrace_seq __read_mostly = 1;

/*

 * Send out a notify message.

 */

static void trace_note(struct blk_trace *bt, pid_t pid, int action,

                       const void *data, size_t len)

{

        struct blk_io_trace *t;

        t = relay_reserve(bt->rchan, sizeof(*t) + len);

        if (t) {

                const int cpu = smp_processor_id();

                t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

                t->time = ktime_to_ns(ktime_get());

                t->device = bt->dev;

                t->action = action;

                t->pid = pid;

                t->cpu = cpu;

                t->pdu_len = len;

                memcpy((void *) t + sizeof(*t), data, len);

        }

}

/*

 * Send out a notify for this process, if we haven't done so since a trace

 * started

 */

static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)

{

        tsk->btrace_seq = blktrace_seq;

        trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));

}

static void trace_note_time(struct blk_trace *bt)

{

        struct timespec now;

        unsigned long flags;

        u32 words[2];

        getnstimeofday(&now);

        words[0] = now.tv_sec;

        words[1] = now.tv_nsec;

        local_irq_save(flags);

        trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));

        local_irq_restore(flags);

}

static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,

                         pid_t pid)

{

        if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)

                return 1;

        if (sector < bt->start_lba || sector > bt->end_lba)

                return 1;

        if (bt->pid && pid != bt->pid)

                return 1;

        return 0;

}

/*

 * Data direction bit lookup

 */

static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) };

/*

 * Bio action bits of interest

 */

static u32 bio_act[9] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD), 0, 0, 0, BLK_TC_ACT(BLK_TC_META) };

/*

 * More could be added as needed, taking care to increment the decrementer

 * to get correct indexing

 */

#define trace_barrier_bit(rw)   \

        (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))

#define trace_sync_bit(rw)      \

        (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))

#define trace_ahead_bit(rw)     \

        (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))

#define trace_meta_bit(rw)      \

        (((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3))

/*

 * The worker for the various blk_add_trace*() types. Fills out a

 * blk_io_trace structure and places it in a per-cpu subbuffer.

 */

void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,

                     int rw, u32 what, int error, int pdu_len, void *pdu_data)

{

        struct task_struct *tsk = current;

        struct blk_io_trace *t;

        unsigned long flags;

        unsigned long *sequence;

        pid_t pid;

        int cpu;

        if (unlikely(bt->trace_state != Blktrace_running))

                return;

        what |= ddir_act[rw & WRITE];

        what |= bio_act[trace_barrier_bit(rw)];

        what |= bio_act[trace_sync_bit(rw)];

        what |= bio_act[trace_ahead_bit(rw)];

        what |= bio_act[trace_meta_bit(rw)];

        pid = tsk->pid;

        if (unlikely(act_log_check(bt, what, sector, pid)))

                return;

        /*

         * A word about the locking here - we disable interrupts to reserve

         * some space in the relay per-cpu buffer, to prevent an irq

         * from coming in and stepping on our toes. Once reserved, it's

         * enough to get preemption disabled to prevent read of this data

         * before we are through filling it. get_cpu()/put_cpu() does this

         * for us

         */

        local_irq_save(flags);

        if (unlikely(tsk->btrace_seq != blktrace_seq))

                trace_note_tsk(bt, tsk);

        t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);

        if (t) {

                cpu = smp_processor_id();

                sequence = per_cpu_ptr(bt->sequence, cpu);

                t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

                t->sequence = ++(*sequence);

                t->time = ktime_to_ns(ktime_get());

                t->sector = sector;

                t->bytes = bytes;

                t->action = what;

                t->pid = pid;

                t->device = bt->dev;

                t->cpu = cpu;

                t->error = error;

                t->pdu_len = pdu_len;

                if (pdu_len)

                        memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);

        }

        local_irq_restore(flags);

}

EXPORT_SYMBOL_GPL(__blk_add_trace);

static struct dentry *blk_tree_root;

static DEFINE_MUTEX(blk_tree_mutex);

static unsigned int root_users;

static inline void blk_remove_root(void)

{

        if (blk_tree_root) {

                debugfs_remove(blk_tree_root);

                blk_tree_root = NULL;

        }

}

static void blk_remove_tree(struct dentry *dir)

{

        mutex_lock(&blk_tree_mutex);

        debugfs_remove(dir);

        if (--root_users == 0)

                blk_remove_root();

        mutex_unlock(&blk_tree_mutex);

}

static struct dentry *blk_create_tree(const char *blk_name)

{

        struct dentry *dir = NULL;

        int created = 0;

        mutex_lock(&blk_tree_mutex);

        if (!blk_tree_root) {

                blk_tree_root = debugfs_create_dir("block", NULL);

                if (!blk_tree_root)

                        goto err;

                created = 1;

        }

        dir = debugfs_create_dir(blk_name, blk_tree_root);

        if (dir)

                root_users++;

        else {

                /* Delete root only if we created it */

                if (created)

                        blk_remove_root();

        }

err:

        mutex_unlock(&blk_tree_mutex);

        return dir;

}

static void blk_trace_cleanup(struct blk_trace *bt)

{

        relay_close(bt->rchan);

        debugfs_remove(bt->dropped_file);

        blk_remove_tree(bt->dir);

        free_percpu(bt->sequence);

        kfree(bt);

}

static int blk_trace_remove(struct request_queue *q)

{

        struct blk_trace *bt;

        bt = xchg(&q->blk_trace, NULL);

        if (!bt)

                return -EINVAL;

        if (bt->trace_state == Blktrace_setup ||

            bt->trace_state == Blktrace_stopped)

                blk_trace_cleanup(bt);

        return 0;

}

static int blk_dropped_open(struct inode *inode, struct file *filp)

{

        filp->private_data = inode->i_private;

        return 0;

}

static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,

                                size_t count, loff_t *ppos)

{

        struct blk_trace *bt = filp->private_data;

        char buf[16];

        snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));

        return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));

}

static const struct file_operations blk_dropped_fops = {

        .owner =        THIS_MODULE,

        .open =         blk_dropped_open,

        .read =         blk_dropped_read,

};

/*

 * Keep track of how many times we encountered a full subbuffer, to aid

 * the user space app in telling how many lost events there were.

 */

static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,

                                     void *prev_subbuf, size_t prev_padding)

{

        struct blk_trace *bt;

        if (!relay_buf_full(buf))

                return 1;

        bt = buf->chan->private_data;

        atomic_inc(&bt->dropped);

        return 0;

}

static int blk_remove_buf_file_callback(struct dentry *dentry)

{

        debugfs_remove(dentry);

        return 0;

}

static struct dentry *blk_create_buf_file_callback(const char *filename,

                                                   struct dentry *parent,

                                                   int mode,

                                                   struct rchan_buf *buf,

                                                   int *is_global)

{

        return debugfs_create_file(filename, mode, parent, buf,

                                        &relay_file_operations);

}

static struct rchan_callbacks blk_relay_callbacks = {

        .subbuf_start           = blk_subbuf_start_callback,

        .create_buf_file        = blk_create_buf_file_callback,

        .remove_buf_file        = blk_remove_buf_file_callback,

};

/*

 * Setup everything required to start tracing

 */

int do_blk_trace_setup(struct request_queue *q, struct block_device *bdev,

                        struct blk_user_trace_setup *buts)

{

        struct blk_trace *old_bt, *bt = NULL;

        struct dentry *dir = NULL;

        char b[BDEVNAME_SIZE];

        int ret, i;

        if (!buts->buf_size || !buts->buf_nr)

                return -EINVAL;

        strcpy(buts->name, bdevname(bdev, b));

        /*

         * some device names have larger paths - convert the slashes

         * to underscores for this to work as expected

         */

        for (i = 0; i < strlen(buts->name); i++)

                if (buts->name[i] == '/')

                        buts->name[i] = '_';

        ret = -ENOMEM;

        bt = kzalloc(sizeof(*bt), GFP_KERNEL);

        if (!bt)

                goto err;

        bt->sequence = alloc_percpu(unsigned long);

        if (!bt->sequence)

                goto err;

        ret = -ENOENT;

        dir = blk_create_tree(buts->name);

        if (!dir)

                goto err;

        bt->dir = dir;

        bt->dev = bdev->bd_dev;

        atomic_set(&bt->dropped, 0);

        ret = -EIO;

        bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);

        if (!bt->dropped_file)

                goto err;

        bt->rchan = relay_open("trace", dir, buts->buf_size,

                                buts->buf_nr, &blk_relay_callbacks, bt);

        if (!bt->rchan)

                goto err;

        bt->act_mask = buts->act_mask;

        if (!bt->act_mask)

                bt->act_mask = (u16) -1;

        bt->start_lba = buts->start_lba;

        bt->end_lba = buts->end_lba;

        if (!bt->end_lba)

                bt->end_lba = -1ULL;

        bt->pid = buts->pid;

        bt->trace_state = Blktrace_setup;

        ret = -EBUSY;

        old_bt = xchg(&q->blk_trace, bt);

        if (old_bt) {

                (void) xchg(&q->blk_trace, old_bt);

                goto err;

        }

        return 0;

err:

        if (dir)

                blk_remove_tree(dir);

        if (bt) {

                if (bt->dropped_file)

                        debugfs_remove(bt->dropped_file);

                free_percpu(bt->sequence);

                if (bt->rchan)

                        relay_close(bt->rchan);

                kfree(bt);

        }

        return ret;

}

static int blk_trace_setup(struct request_queue *q, struct block_device *bdev,

                           char __user *arg)

{

        struct blk_user_trace_setup buts;

        int ret;

        ret = copy_from_user(&buts, arg, sizeof(buts));

        if (ret)

                return -EFAULT;

        ret = do_blk_trace_setup(q, bdev, &buts);

        if (ret)

                return ret;

        if (copy_to_user(arg, &buts, sizeof(buts)))

                return -EFAULT;

        return 0;

}

static int blk_trace_startstop(struct request_queue *q, int start)

{

        struct blk_trace *bt;

        int ret;

        if ((bt = q->blk_trace) == NULL)

                return -EINVAL;

        /*

         * For starting a trace, we can transition from a setup or stopped

         * trace. For stopping a trace, the state must be running

         */

        ret = -EINVAL;

        if (start) {

                if (bt->trace_state == Blktrace_setup ||

                    bt->trace_state == Blktrace_stopped) {

                        blktrace_seq++;

                        smp_mb();

                        bt->trace_state = Blktrace_running;

                        trace_note_time(bt);

                        ret = 0;

                }

        } else {

                if (bt->trace_state == Blktrace_running) {

                        bt->trace_state = Blktrace_stopped;

                        relay_flush(bt->rchan);

                        ret = 0;

                }

        }

        return ret;

}

/**

 * blk_trace_ioctl: - handle the ioctls associated with tracing

 * @bdev:       the block device

 * @cmd:        the ioctl cmd

 * @arg:        the argument data, if any

 *

 **/

int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)

{

        struct request_queue *q;

        int ret, start = 0;

        q = bdev_get_queue(bdev);

        if (!q)

                return -ENXIO;

        mutex_lock(&bdev->bd_mutex);

        switch (cmd) {

        case BLKTRACESETUP:

                ret = blk_trace_setup(q, bdev, arg);

                break;

        case BLKTRACESTART:

                start = 1;

        case BLKTRACESTOP:

                ret = blk_trace_startstop(q, start);

                break;

        case BLKTRACETEARDOWN:

                ret = blk_trace_remove(q);

                break;

        default:

                ret = -ENOTTY;

                break;

        }

        mutex_unlock(&bdev->bd_mutex);

        return ret;

}

/**

 * blk_trace_shutdown: - stop and cleanup trace structures

 * @q:    the request queue associated with the device

 *

 **/

void blk_trace_shutdown(struct request_queue *q)

{

        if (q->blk_trace) {

                blk_trace_startstop(q, 0);

                blk_trace_remove(q);

        }

}