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    Subject[patch 25/45] SCSI: sg: fix races during device removal
    -stable review patch.  If anyone has any objections, please let us know.
    ---------------------

    From: Tony Battersby <tonyb@cybernetics.com>

    upstream commit: c6517b7942fad663cc1cf3235cbe4207cf769332

    sg has the following problems related to device removal:

    * opening a sg fd races with removing a device
    * closing a sg fd races with removing a device
    * /proc/scsi/sg/* access races with removing a device
    * command completion races with removing a device
    * command completion races with closing a sg fd
    * can rmmod sg with active commands

    These problems can cause kernel oopses, memory-use-after-free, or
    double-free errors. This patch fixes these problems by using krefs
    to manage the lifetime of sg_device and sg_fd.

    Each command submitted to the midlevel holds a reference to sg_fd
    until the completion callback. This ensures that sg_fd doesn't go
    away if the fd is closed with commands still outstanding.

    sg_fd gets the reference of sg_device (with scsi_device) and also
    makes sure that the sg module doesn't go away.

    /proc/scsi/sg/* functions don't play nicely with krefs because they
    give information about sg_fds which have been closed but not yet
    freed due to still having outstanding commands and sg_devices which
    have been removed but not yet freed due to still being referenced
    by one or more sg_fds. To deal with this safely without removing
    functionality, /proc functions now access sg_device and sg_fd while
    holding a lock instead of using kref_get()/kref_put().

    Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
    Acked-by: Douglas Gilbert <dgilbert@interlog.com>
    Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
    Signed-off-by: Chris Wright <chrisw@sous-sol.org>
    ---
    drivers/scsi/sg.c | 418 +++++++++++++++++++++++++-----------------------------
    1 file changed, 201 insertions(+), 217 deletions(-)

    --- a/drivers/scsi/sg.c
    +++ b/drivers/scsi/sg.c
    @@ -101,6 +101,7 @@ static int scatter_elem_sz_prev = SG_SCA
    #define SG_SECTOR_MSK (SG_SECTOR_SZ - 1)

    static int sg_add(struct device *, struct class_interface *);
    +static void sg_device_destroy(struct kref *kref);
    static void sg_remove(struct device *, struct class_interface *);

    static DEFINE_IDR(sg_index_idr);
    @@ -158,6 +159,8 @@ typedef struct sg_fd { /* holds the sta
    char next_cmd_len; /* 0 -> automatic (def), >0 -> use on next write() */
    char keep_orphan; /* 0 -> drop orphan (def), 1 -> keep for read() */
    char mmap_called; /* 0 -> mmap() never called on this fd */
    + struct kref f_ref;
    + struct execute_work ew;
    } Sg_fd;

    typedef struct sg_device { /* holds the state of each scsi generic device */
    @@ -171,6 +174,7 @@ typedef struct sg_device { /* holds the
    char sgdebug; /* 0->off, 1->sense, 9->dump dev, 10-> all devs */
    struct gendisk *disk;
    struct cdev * cdev; /* char_dev [sysfs: /sys/cdev/major/sg<n>] */
    + struct kref d_ref;
    } Sg_device;

    static int sg_fasync(int fd, struct file *filp, int mode);
    @@ -194,13 +198,14 @@ static void sg_build_reserve(Sg_fd * sfp
    static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size);
    static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp);
    static Sg_fd *sg_add_sfp(Sg_device * sdp, int dev);
    -static int sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp);
    -static void __sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp);
    +static void sg_remove_sfp(struct kref *);
    static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id);
    static Sg_request *sg_add_request(Sg_fd * sfp);
    static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
    static int sg_res_in_use(Sg_fd * sfp);
    +static Sg_device *sg_lookup_dev(int dev);
    static Sg_device *sg_get_dev(int dev);
    +static void sg_put_dev(Sg_device *sdp);
    #ifdef CONFIG_SCSI_PROC_FS
    static int sg_last_dev(void);
    #endif
    @@ -237,22 +242,17 @@ sg_open(struct inode *inode, struct file
    nonseekable_open(inode, filp);
    SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags));
    sdp = sg_get_dev(dev);
    - if ((!sdp) || (!sdp->device)) {
    - unlock_kernel();
    - return -ENXIO;
    - }
    - if (sdp->detached) {
    - unlock_kernel();
    - return -ENODEV;
    + if (IS_ERR(sdp)) {
    + retval = PTR_ERR(sdp);
    + sdp = NULL;
    + goto sg_put;
    }

    /* This driver's module count bumped by fops_get in <linux/fs.h> */
    /* Prevent the device driver from vanishing while we sleep */
    retval = scsi_device_get(sdp->device);
    - if (retval) {
    - unlock_kernel();
    - return retval;
    - }
    + if (retval)
    + goto sg_put;

    if (!((flags & O_NONBLOCK) ||
    scsi_block_when_processing_errors(sdp->device))) {
    @@ -303,16 +303,20 @@ sg_open(struct inode *inode, struct file
    if ((sfp = sg_add_sfp(sdp, dev)))
    filp->private_data = sfp;
    else {
    - if (flags & O_EXCL)
    + if (flags & O_EXCL) {
    sdp->exclude = 0; /* undo if error */
    + wake_up_interruptible(&sdp->o_excl_wait);
    + }
    retval = -ENOMEM;
    goto error_out;
    }
    - unlock_kernel();
    - return 0;
    -
    - error_out:
    - scsi_device_put(sdp->device);
    + retval = 0;
    +error_out:
    + if (retval)
    + scsi_device_put(sdp->device);
    +sg_put:
    + if (sdp)
    + sg_put_dev(sdp);
    unlock_kernel();
    return retval;
    }
    @@ -327,13 +331,13 @@ sg_release(struct inode *inode, struct f
    if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
    return -ENXIO;
    SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name));
    - if (0 == sg_remove_sfp(sdp, sfp)) { /* Returns 1 when sdp gone */
    - if (!sdp->detached) {
    - scsi_device_put(sdp->device);
    - }
    - sdp->exclude = 0;
    - wake_up_interruptible(&sdp->o_excl_wait);
    - }
    +
    + sfp->closed = 1;
    +
    + sdp->exclude = 0;
    + wake_up_interruptible(&sdp->o_excl_wait);
    +
    + kref_put(&sfp->f_ref, sg_remove_sfp);
    return 0;
    }

    @@ -755,6 +759,7 @@ sg_common_write(Sg_fd * sfp, Sg_request
    hp->duration = jiffies_to_msecs(jiffies);

    srp->rq->timeout = timeout;
    + kref_get(&sfp->f_ref); /* sg_rq_end_io() does kref_put(). */
    blk_execute_rq_nowait(sdp->device->request_queue, sdp->disk,
    srp->rq, 1, sg_rq_end_io);
    return 0;
    @@ -1247,24 +1252,23 @@ sg_mmap(struct file *filp, struct vm_are
    static void sg_rq_end_io(struct request *rq, int uptodate)
    {
    struct sg_request *srp = rq->end_io_data;
    - Sg_device *sdp = NULL;
    + Sg_device *sdp;
    Sg_fd *sfp;
    unsigned long iflags;
    unsigned int ms;
    char *sense;
    - int result, resid;
    + int result, resid, done = 1;

    - if (NULL == srp) {
    - printk(KERN_ERR "sg_cmd_done: NULL request\n");
    + if (WARN_ON(srp->done != 0))
    return;
    - }
    +
    sfp = srp->parentfp;
    - if (sfp)
    - sdp = sfp->parentdp;
    - if ((NULL == sdp) || sdp->detached) {
    - printk(KERN_INFO "sg_cmd_done: device detached\n");
    + if (WARN_ON(sfp == NULL))
    return;
    - }
    +
    + sdp = sfp->parentdp;
    + if (unlikely(sdp->detached))
    + printk(KERN_INFO "sg_rq_end_io: device detached\n");

    sense = rq->sense;
    result = rq->errors;
    @@ -1303,33 +1307,26 @@ static void sg_rq_end_io(struct request
    }
    /* Rely on write phase to clean out srp status values, so no "else" */

    - if (sfp->closed) { /* whoops this fd already released, cleanup */
    - SCSI_LOG_TIMEOUT(1, printk("sg_cmd_done: already closed, freeing ...\n"));
    - sg_finish_rem_req(srp);
    - srp = NULL;
    - if (NULL == sfp->headrp) {
    - SCSI_LOG_TIMEOUT(1, printk("sg_cmd_done: already closed, final cleanup\n"));
    - if (0 == sg_remove_sfp(sdp, sfp)) { /* device still present */
    - scsi_device_put(sdp->device);
    - }
    - sfp = NULL;
    - }
    - } else if (srp && srp->orphan) {
    + write_lock_irqsave(&sfp->rq_list_lock, iflags);
    + if (unlikely(srp->orphan)) {
    if (sfp->keep_orphan)
    srp->sg_io_owned = 0;
    - else {
    - sg_finish_rem_req(srp);
    - srp = NULL;
    - }
    + else
    + done = 0;
    }
    - if (sfp && srp) {
    - /* Now wake up any sg_read() that is waiting for this packet. */
    - kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
    - write_lock_irqsave(&sfp->rq_list_lock, iflags);
    - srp->done = 1;
    + srp->done = done;
    + write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
    +
    + if (likely(done)) {
    + /* Now wake up any sg_read() that is waiting for this
    + * packet.
    + */
    wake_up_interruptible(&sfp->read_wait);
    - write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
    - }
    + kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
    + } else
    + sg_finish_rem_req(srp); /* call with srp->done == 0 */
    +
    + kref_put(&sfp->f_ref, sg_remove_sfp);
    }

    static struct file_operations sg_fops = {
    @@ -1364,17 +1361,18 @@ static Sg_device *sg_alloc(struct gendis
    printk(KERN_WARNING "kmalloc Sg_device failure\n");
    return ERR_PTR(-ENOMEM);
    }
    - error = -ENOMEM;
    +
    if (!idr_pre_get(&sg_index_idr, GFP_KERNEL)) {
    printk(KERN_WARNING "idr expansion Sg_device failure\n");
    + error = -ENOMEM;
    goto out;
    }

    write_lock_irqsave(&sg_index_lock, iflags);
    - error = idr_get_new(&sg_index_idr, sdp, &k);
    - write_unlock_irqrestore(&sg_index_lock, iflags);

    + error = idr_get_new(&sg_index_idr, sdp, &k);
    if (error) {
    + write_unlock_irqrestore(&sg_index_lock, iflags);
    printk(KERN_WARNING "idr allocation Sg_device failure: %d\n",
    error);
    goto out;
    @@ -1391,6 +1389,9 @@ static Sg_device *sg_alloc(struct gendis
    init_waitqueue_head(&sdp->o_excl_wait);
    sdp->sg_tablesize = min(q->max_hw_segments, q->max_phys_segments);
    sdp->index = k;
    + kref_init(&sdp->d_ref);
    +
    + write_unlock_irqrestore(&sg_index_lock, iflags);

    error = 0;
    out:
    @@ -1401,6 +1402,8 @@ static Sg_device *sg_alloc(struct gendis
    return sdp;

    overflow:
    + idr_remove(&sg_index_idr, k);
    + write_unlock_irqrestore(&sg_index_lock, iflags);
    sdev_printk(KERN_WARNING, scsidp,
    "Unable to attach sg device type=%d, minor "
    "number exceeds %d\n", scsidp->type, SG_MAX_DEVS - 1);
    @@ -1488,49 +1491,46 @@ out:
    return error;
    }

    -static void
    -sg_remove(struct device *cl_dev, struct class_interface *cl_intf)
    +static void sg_device_destroy(struct kref *kref)
    +{
    + struct sg_device *sdp = container_of(kref, struct sg_device, d_ref);
    + unsigned long flags;
    +
    + /* CAUTION! Note that the device can still be found via idr_find()
    + * even though the refcount is 0. Therefore, do idr_remove() BEFORE
    + * any other cleanup.
    + */
    +
    + write_lock_irqsave(&sg_index_lock, flags);
    + idr_remove(&sg_index_idr, sdp->index);
    + write_unlock_irqrestore(&sg_index_lock, flags);
    +
    + SCSI_LOG_TIMEOUT(3,
    + printk("sg_device_destroy: %s\n",
    + sdp->disk->disk_name));
    +
    + put_disk(sdp->disk);
    + kfree(sdp);
    +}
    +
    +static void sg_remove(struct device *cl_dev, struct class_interface *cl_intf)
    {
    struct scsi_device *scsidp = to_scsi_device(cl_dev->parent);
    Sg_device *sdp = dev_get_drvdata(cl_dev);
    unsigned long iflags;
    Sg_fd *sfp;
    - Sg_fd *tsfp;
    - Sg_request *srp;
    - Sg_request *tsrp;
    - int delay;

    - if (!sdp)
    + if (!sdp || sdp->detached)
    return;

    - delay = 0;
    + SCSI_LOG_TIMEOUT(3, printk("sg_remove: %s\n", sdp->disk->disk_name));
    +
    + /* Need a write lock to set sdp->detached. */
    write_lock_irqsave(&sg_index_lock, iflags);
    - if (sdp->headfp) {
    - sdp->detached = 1;
    - for (sfp = sdp->headfp; sfp; sfp = tsfp) {
    - tsfp = sfp->nextfp;
    - for (srp = sfp->headrp; srp; srp = tsrp) {
    - tsrp = srp->nextrp;
    - if (sfp->closed || (0 == sg_srp_done(srp, sfp)))
    - sg_finish_rem_req(srp);
    - }
    - if (sfp->closed) {
    - scsi_device_put(sdp->device);
    - __sg_remove_sfp(sdp, sfp);
    - } else {
    - delay = 1;
    - wake_up_interruptible(&sfp->read_wait);
    - kill_fasync(&sfp->async_qp, SIGPOLL,
    - POLL_HUP);
    - }
    - }
    - SCSI_LOG_TIMEOUT(3, printk("sg_remove: dev=%d, dirty\n", sdp->index));
    - if (NULL == sdp->headfp) {
    - idr_remove(&sg_index_idr, sdp->index);
    - }
    - } else { /* nothing active, simple case */
    - SCSI_LOG_TIMEOUT(3, printk("sg_remove: dev=%d\n", sdp->index));
    - idr_remove(&sg_index_idr, sdp->index);
    + sdp->detached = 1;
    + for (sfp = sdp->headfp; sfp; sfp = sfp->nextfp) {
    + wake_up_interruptible(&sfp->read_wait);
    + kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
    }
    write_unlock_irqrestore(&sg_index_lock, iflags);

    @@ -1538,13 +1538,8 @@ sg_remove(struct device *cl_dev, struct
    device_destroy(sg_sysfs_class, MKDEV(SCSI_GENERIC_MAJOR, sdp->index));
    cdev_del(sdp->cdev);
    sdp->cdev = NULL;
    - put_disk(sdp->disk);
    - sdp->disk = NULL;
    - if (NULL == sdp->headfp)
    - kfree(sdp);

    - if (delay)
    - msleep(10); /* dirty detach so delay device destruction */
    + sg_put_dev(sdp);
    }

    module_param_named(scatter_elem_sz, scatter_elem_sz, int, S_IRUGO | S_IWUSR);
    @@ -1941,22 +1936,6 @@ sg_get_rq_mark(Sg_fd * sfp, int pack_id)
    return resp;
    }

    -#ifdef CONFIG_SCSI_PROC_FS
    -static Sg_request *
    -sg_get_nth_request(Sg_fd * sfp, int nth)
    -{
    - Sg_request *resp;
    - unsigned long iflags;
    - int k;
    -
    - read_lock_irqsave(&sfp->rq_list_lock, iflags);
    - for (k = 0, resp = sfp->headrp; resp && (k < nth);
    - ++k, resp = resp->nextrp) ;
    - read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
    - return resp;
    -}
    -#endif
    -
    /* always adds to end of list */
    static Sg_request *
    sg_add_request(Sg_fd * sfp)
    @@ -2032,22 +2011,6 @@ sg_remove_request(Sg_fd * sfp, Sg_reques
    return res;
    }

    -#ifdef CONFIG_SCSI_PROC_FS
    -static Sg_fd *
    -sg_get_nth_sfp(Sg_device * sdp, int nth)
    -{
    - Sg_fd *resp;
    - unsigned long iflags;
    - int k;
    -
    - read_lock_irqsave(&sg_index_lock, iflags);
    - for (k = 0, resp = sdp->headfp; resp && (k < nth);
    - ++k, resp = resp->nextfp) ;
    - read_unlock_irqrestore(&sg_index_lock, iflags);
    - return resp;
    -}
    -#endif
    -
    static Sg_fd *
    sg_add_sfp(Sg_device * sdp, int dev)
    {
    @@ -2062,6 +2025,7 @@ sg_add_sfp(Sg_device * sdp, int dev)
    init_waitqueue_head(&sfp->read_wait);
    rwlock_init(&sfp->rq_list_lock);

    + kref_init(&sfp->f_ref);
    sfp->timeout = SG_DEFAULT_TIMEOUT;
    sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
    sfp->force_packid = SG_DEF_FORCE_PACK_ID;
    @@ -2089,15 +2053,54 @@ sg_add_sfp(Sg_device * sdp, int dev)
    sg_build_reserve(sfp, bufflen);
    SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: bufflen=%d, k_use_sg=%d\n",
    sfp->reserve.bufflen, sfp->reserve.k_use_sg));
    +
    + kref_get(&sdp->d_ref);
    + __module_get(THIS_MODULE);
    return sfp;
    }

    -static void
    -__sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp)
    +static void sg_remove_sfp_usercontext(struct work_struct *work)
    +{
    + struct sg_fd *sfp = container_of(work, struct sg_fd, ew.work);
    + struct sg_device *sdp = sfp->parentdp;
    +
    + /* Cleanup any responses which were never read(). */
    + while (sfp->headrp)
    + sg_finish_rem_req(sfp->headrp);
    +
    + if (sfp->reserve.bufflen > 0) {
    + SCSI_LOG_TIMEOUT(6,
    + printk("sg_remove_sfp: bufflen=%d, k_use_sg=%d\n",
    + (int) sfp->reserve.bufflen,
    + (int) sfp->reserve.k_use_sg));
    + sg_remove_scat(&sfp->reserve);
    + }
    +
    + SCSI_LOG_TIMEOUT(6,
    + printk("sg_remove_sfp: %s, sfp=0x%p\n",
    + sdp->disk->disk_name,
    + sfp));
    + kfree(sfp);
    +
    + scsi_device_put(sdp->device);
    + sg_put_dev(sdp);
    + module_put(THIS_MODULE);
    +}
    +
    +static void sg_remove_sfp(struct kref *kref)
    {
    + struct sg_fd *sfp = container_of(kref, struct sg_fd, f_ref);
    + struct sg_device *sdp = sfp->parentdp;
    Sg_fd *fp;
    Sg_fd *prev_fp;
    + unsigned long iflags;
    +
    + /* CAUTION! Note that sfp can still be found by walking sdp->headfp
    + * even though the refcount is now 0. Therefore, unlink sfp from
    + * sdp->headfp BEFORE doing any other cleanup.
    + */

    + write_lock_irqsave(&sg_index_lock, iflags);
    prev_fp = sdp->headfp;
    if (sfp == prev_fp)
    sdp->headfp = prev_fp->nextfp;
    @@ -2110,54 +2113,10 @@ __sg_remove_sfp(Sg_device * sdp, Sg_fd *
    prev_fp = fp;
    }
    }
    - if (sfp->reserve.bufflen > 0) {
    - SCSI_LOG_TIMEOUT(6,
    - printk("__sg_remove_sfp: bufflen=%d, k_use_sg=%d\n",
    - (int) sfp->reserve.bufflen, (int) sfp->reserve.k_use_sg));
    - sg_remove_scat(&sfp->reserve);
    - }
    - sfp->parentdp = NULL;
    - SCSI_LOG_TIMEOUT(6, printk("__sg_remove_sfp: sfp=0x%p\n", sfp));
    - kfree(sfp);
    -}
    -
    -/* Returns 0 in normal case, 1 when detached and sdp object removed */
    -static int
    -sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp)
    -{
    - Sg_request *srp;
    - Sg_request *tsrp;
    - int dirty = 0;
    - int res = 0;
    -
    - for (srp = sfp->headrp; srp; srp = tsrp) {
    - tsrp = srp->nextrp;
    - if (sg_srp_done(srp, sfp))
    - sg_finish_rem_req(srp);
    - else
    - ++dirty;
    - }
    - if (0 == dirty) {
    - unsigned long iflags;
    + write_unlock_irqrestore(&sg_index_lock, iflags);
    + wake_up_interruptible(&sdp->o_excl_wait);

    - write_lock_irqsave(&sg_index_lock, iflags);
    - __sg_remove_sfp(sdp, sfp);
    - if (sdp->detached && (NULL == sdp->headfp)) {
    - idr_remove(&sg_index_idr, sdp->index);
    - kfree(sdp);
    - res = 1;
    - }
    - write_unlock_irqrestore(&sg_index_lock, iflags);
    - } else {
    - /* MOD_INC's to inhibit unloading sg and associated adapter driver */
    - /* only bump the access_count if we actually succeeded in
    - * throwing another counter on the host module */
    - scsi_device_get(sdp->device); /* XXX: retval ignored? */
    - sfp->closed = 1; /* flag dirty state on this fd */
    - SCSI_LOG_TIMEOUT(1, printk("sg_remove_sfp: worrisome, %d writes pending\n",
    - dirty));
    - }
    - return res;
    + execute_in_process_context(sg_remove_sfp_usercontext, &sfp->ew);
    }

    static int
    @@ -2199,19 +2158,38 @@ sg_last_dev(void)
    }
    #endif

    -static Sg_device *
    -sg_get_dev(int dev)
    +/* must be called with sg_index_lock held */
    +static Sg_device *sg_lookup_dev(int dev)
    {
    - Sg_device *sdp;
    - unsigned long iflags;
    + return idr_find(&sg_index_idr, dev);
    +}

    - read_lock_irqsave(&sg_index_lock, iflags);
    - sdp = idr_find(&sg_index_idr, dev);
    - read_unlock_irqrestore(&sg_index_lock, iflags);
    +static Sg_device *sg_get_dev(int dev)
    +{
    + struct sg_device *sdp;
    + unsigned long flags;
    +
    + read_lock_irqsave(&sg_index_lock, flags);
    + sdp = sg_lookup_dev(dev);
    + if (!sdp)
    + sdp = ERR_PTR(-ENXIO);
    + else if (sdp->detached) {
    + /* If sdp->detached, then the refcount may already be 0, in
    + * which case it would be a bug to do kref_get().
    + */
    + sdp = ERR_PTR(-ENODEV);
    + } else
    + kref_get(&sdp->d_ref);
    + read_unlock_irqrestore(&sg_index_lock, flags);

    return sdp;
    }

    +static void sg_put_dev(struct sg_device *sdp)
    +{
    + kref_put(&sdp->d_ref, sg_device_destroy);
    +}
    +
    #ifdef CONFIG_SCSI_PROC_FS

    static struct proc_dir_entry *sg_proc_sgp = NULL;
    @@ -2468,8 +2446,10 @@ static int sg_proc_seq_show_dev(struct s
    struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
    Sg_device *sdp;
    struct scsi_device *scsidp;
    + unsigned long iflags;

    - sdp = it ? sg_get_dev(it->index) : NULL;
    + read_lock_irqsave(&sg_index_lock, iflags);
    + sdp = it ? sg_lookup_dev(it->index) : NULL;
    if (sdp && (scsidp = sdp->device) && (!sdp->detached))
    seq_printf(s, "%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\n",
    scsidp->host->host_no, scsidp->channel,
    @@ -2480,6 +2460,7 @@ static int sg_proc_seq_show_dev(struct s
    (int) scsi_device_online(scsidp));
    else
    seq_printf(s, "-1\t-1\t-1\t-1\t-1\t-1\t-1\t-1\t-1\n");
    + read_unlock_irqrestore(&sg_index_lock, iflags);
    return 0;
    }

    @@ -2493,16 +2474,20 @@ static int sg_proc_seq_show_devstrs(stru
    struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
    Sg_device *sdp;
    struct scsi_device *scsidp;
    + unsigned long iflags;

    - sdp = it ? sg_get_dev(it->index) : NULL;
    + read_lock_irqsave(&sg_index_lock, iflags);
    + sdp = it ? sg_lookup_dev(it->index) : NULL;
    if (sdp && (scsidp = sdp->device) && (!sdp->detached))
    seq_printf(s, "%8.8s\t%16.16s\t%4.4s\n",
    scsidp->vendor, scsidp->model, scsidp->rev);
    else
    seq_printf(s, "<no active device>\n");
    + read_unlock_irqrestore(&sg_index_lock, iflags);
    return 0;
    }

    +/* must be called while holding sg_index_lock */
    static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
    {
    int k, m, new_interface, blen, usg;
    @@ -2512,7 +2497,8 @@ static void sg_proc_debug_helper(struct
    const char * cp;
    unsigned int ms;

    - for (k = 0; (fp = sg_get_nth_sfp(sdp, k)); ++k) {
    + for (k = 0, fp = sdp->headfp; fp != NULL; ++k, fp = fp->nextfp) {
    + read_lock(&fp->rq_list_lock); /* irqs already disabled */
    seq_printf(s, " FD(%d): timeout=%dms bufflen=%d "
    "(res)sgat=%d low_dma=%d\n", k + 1,
    jiffies_to_msecs(fp->timeout),
    @@ -2522,7 +2508,9 @@ static void sg_proc_debug_helper(struct
    seq_printf(s, " cmd_q=%d f_packid=%d k_orphan=%d closed=%d\n",
    (int) fp->cmd_q, (int) fp->force_packid,
    (int) fp->keep_orphan, (int) fp->closed);
    - for (m = 0; (srp = sg_get_nth_request(fp, m)); ++m) {
    + for (m = 0, srp = fp->headrp;
    + srp != NULL;
    + ++m, srp = srp->nextrp) {
    hp = &srp->header;
    new_interface = (hp->interface_id == '\0') ? 0 : 1;
    if (srp->res_used) {
    @@ -2559,6 +2547,7 @@ static void sg_proc_debug_helper(struct
    }
    if (0 == m)
    seq_printf(s, " No requests active\n");
    + read_unlock(&fp->rq_list_lock);
    }
    }

    @@ -2571,39 +2560,34 @@ static int sg_proc_seq_show_debug(struct
    {
    struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
    Sg_device *sdp;
    + unsigned long iflags;

    if (it && (0 == it->index)) {
    seq_printf(s, "max_active_device=%d(origin 1)\n",
    (int)it->max);
    seq_printf(s, " def_reserved_size=%d\n", sg_big_buff);
    }
    - sdp = it ? sg_get_dev(it->index) : NULL;
    - if (sdp) {
    - struct scsi_device *scsidp = sdp->device;

    - if (NULL == scsidp) {
    - seq_printf(s, "device %d detached ??\n",
    - (int)it->index);
    - return 0;
    - }
    + read_lock_irqsave(&sg_index_lock, iflags);
    + sdp = it ? sg_lookup_dev(it->index) : NULL;
    + if (sdp && sdp->headfp) {
    + struct scsi_device *scsidp = sdp->device;

    - if (sg_get_nth_sfp(sdp, 0)) {
    - seq_printf(s, " >>> device=%s ",
    - sdp->disk->disk_name);
    - if (sdp->detached)
    - seq_printf(s, "detached pending close ");
    - else
    - seq_printf
    - (s, "scsi%d chan=%d id=%d lun=%d em=%d",
    - scsidp->host->host_no,
    - scsidp->channel, scsidp->id,
    - scsidp->lun,
    - scsidp->host->hostt->emulated);
    - seq_printf(s, " sg_tablesize=%d excl=%d\n",
    - sdp->sg_tablesize, sdp->exclude);
    - }
    + seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);
    + if (sdp->detached)
    + seq_printf(s, "detached pending close ");
    + else
    + seq_printf
    + (s, "scsi%d chan=%d id=%d lun=%d em=%d",
    + scsidp->host->host_no,
    + scsidp->channel, scsidp->id,
    + scsidp->lun,
    + scsidp->host->hostt->emulated);
    + seq_printf(s, " sg_tablesize=%d excl=%d\n",
    + sdp->sg_tablesize, sdp->exclude);
    sg_proc_debug_helper(s, sdp);
    }
    + read_unlock_irqrestore(&sg_index_lock, iflags);
    return 0;
    }



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