Re: [PATCH v3 1/2] mpt2sas: Refcount sas_device objects and fix unsafe list usage

[Calvin Owens <calvinowens@fb.com>]

On Monday 08/10 at 18:45 +0530, Sreekanth Reddy wrote:
> On Sat, Aug 1, 2015 at 10:32 AM, Calvin Owens <calvinowens@fb.com> wrote:

Sreekanth,

Thanks for the review, responses below. I'll have a v4 out shortly.

Calvin

> > These objects can be referenced concurrently throughout the driver, we
> > need a way to make sure threads can't delete them out from under each
> > other. This patch adds the refcount, and refactors the code to use it.
> >
> > Additionally, we cannot iterate over the sas_device_list without
> > holding the lock, or we risk corrupting random memory if items are
> > added or deleted as we iterate. This patch refactors _scsih_probe_sas()
> > to use the sas_device_list in a safe way.
> >
> > Cc: Christoph Hellwig <hch@infradead.org>
> > Cc: Bart Van Assche <bart.vanassche@sandisk.com>
> > Cc: Joe Lawrence <joe.lawrence@stratus.com>
> > Signed-off-by: Calvin Owens <calvinowens@fb.com>
> > ---
> > Changes in v3:
> >         * Drop the sas_device_lock while enabling devices, and leave the
> >           sas_device object on the list, since it may need to be looked up
> >           there while it is being enabled.
> >         * Drop put() in _scsih_add_device(), because the ->hostdata now keeps a
> >           reference (this was an oversight in v2).
> >         * Be consistent about calling sas_device_put() while holding the
> >           sas_device_lock where feasible.
> >         * Take and assert_spin_locked() on the sas_device_lock from the newly
> >           added __get_sdev_from_target(), add wrapper similar to other lookups
> >           for callers which do not explicitly take the lock.
> >
> > Changes in v2:
> >         * Squished patches 1-3 into this one
> >         * s/BUG_ON(!spin_is_locked/assert_spin_locked/g
> >         * Store a pointer to the sas_device object in ->hostdata, to eliminate
> >           the need for several lookups on the lists.
> >
> >  drivers/scsi/mpt2sas/mpt2sas_base.h      |  22 +-
> >  drivers/scsi/mpt2sas/mpt2sas_scsih.c     | 467 +++++++++++++++++++++----------
> >  drivers/scsi/mpt2sas/mpt2sas_transport.c |  12 +-
> >  3 files changed, 348 insertions(+), 153 deletions(-)
> >
> > diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.h b/drivers/scsi/mpt2sas/mpt2sas_base.h
> > index caff8d1..78f41ac 100644
> > --- a/drivers/scsi/mpt2sas/mpt2sas_base.h
> > +++ b/drivers/scsi/mpt2sas/mpt2sas_base.h
> > @@ -238,6 +238,7 @@
> >   * @flags: MPT_TARGET_FLAGS_XXX flags
> >   * @deleted: target flaged for deletion
> >   * @tm_busy: target is busy with TM request.
> > + * @sdev: The sas_device associated with this target
> >   */
> >  struct MPT2SAS_TARGET {
> >         struct scsi_target *starget;
> > @@ -248,6 +249,7 @@ struct MPT2SAS_TARGET {
> >         u32     flags;
> >         u8      deleted;
> >         u8      tm_busy;
> > +       struct _sas_device *sdev;
> >  };
> >
> >
> > @@ -376,8 +378,24 @@ struct _sas_device {
> >         u8      phy;
> >         u8      responding;
> >         u8      pfa_led_on;
> > +       struct kref refcount;
> >  };
> >
> > +static inline void sas_device_get(struct _sas_device *s)
> > +{
> > +       kref_get(&s->refcount);
> > +}
> > +
> > +static inline void sas_device_free(struct kref *r)
> > +{
> > +       kfree(container_of(r, struct _sas_device, refcount));
> > +}
> > +
> > +static inline void sas_device_put(struct _sas_device *s)
> > +{
> > +       kref_put(&s->refcount, sas_device_free);
> > +}
> > +
> >  /**
> >   * struct _raid_device - raid volume link list
> >   * @list: sas device list
> > @@ -1095,7 +1113,9 @@ struct _sas_node *mpt2sas_scsih_expander_find_by_handle(struct MPT2SAS_ADAPTER *
> >      u16 handle);
> >  struct _sas_node *mpt2sas_scsih_expander_find_by_sas_address(struct MPT2SAS_ADAPTER
> >      *ioc, u64 sas_address);
> > -struct _sas_device *mpt2sas_scsih_sas_device_find_by_sas_address(
> > +struct _sas_device *mpt2sas_get_sdev_by_addr(
> > +    struct MPT2SAS_ADAPTER *ioc, u64 sas_address);
> > +struct _sas_device *__mpt2sas_get_sdev_by_addr(
> >      struct MPT2SAS_ADAPTER *ioc, u64 sas_address);
> >
> >  void mpt2sas_port_enable_complete(struct MPT2SAS_ADAPTER *ioc);
> > diff --git a/drivers/scsi/mpt2sas/mpt2sas_scsih.c b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
> > index 3f26147..a2af9a5 100644
> > --- a/drivers/scsi/mpt2sas/mpt2sas_scsih.c
> > +++ b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
> > @@ -526,8 +526,61 @@ _scsih_determine_boot_device(struct MPT2SAS_ADAPTER *ioc,
> >         }
> >  }
> >
> > +static struct _sas_device *
> > +__mpt2sas_get_sdev_from_target(struct MPT2SAS_ADAPTER *ioc,
> > +               struct MPT2SAS_TARGET *tgt_priv)
> > +{
> > +       struct _sas_device *ret;
> > +
> > +       assert_spin_locked(&ioc->sas_device_lock);
> > +
> > +       ret = tgt_priv->sdev;
> > +       if (ret)
> > +               sas_device_get(ret);
> > +
> > +       return ret;
> > +}
> > +
> > +static struct _sas_device *
> > +mpt2sas_get_sdev_from_target(struct MPT2SAS_ADAPTER *ioc,
> > +               struct MPT2SAS_TARGET *tgt_priv)
> > +{
> > +       struct _sas_device *ret;
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +       ret = __mpt2sas_get_sdev_from_target(ioc, tgt_priv);
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +
> > +       return ret;
> > +}
> > +
> > +
> > +struct _sas_device *
> > +__mpt2sas_get_sdev_by_addr(struct MPT2SAS_ADAPTER *ioc,
> > +    u64 sas_address)
> > +{
> > +       struct _sas_device *sas_device;
> > +
> > +       assert_spin_locked(&ioc->sas_device_lock);
> > +
> > +       list_for_each_entry(sas_device, &ioc->sas_device_list, list)
> > +               if (sas_device->sas_address == sas_address)
> > +                       goto found_device;
> > +
> > +       list_for_each_entry(sas_device, &ioc->sas_device_init_list, list)
> > +               if (sas_device->sas_address == sas_address)
> > +                       goto found_device;
> > +
> > +       return NULL;
> > +
> > +found_device:
> > +       sas_device_get(sas_device);
> > +       return sas_device;
> > +}
> > +
> >  /**
> > - * mpt2sas_scsih_sas_device_find_by_sas_address - sas device search
> > + * mpt2sas_get_sdev_by_addr - sas device search
> >   * @ioc: per adapter object
> >   * @sas_address: sas address
> >   * Context: Calling function should acquire ioc->sas_device_lock
> > @@ -536,24 +589,44 @@ _scsih_determine_boot_device(struct MPT2SAS_ADAPTER *ioc,
> >   * object.
> >   */
> >  struct _sas_device *
> > -mpt2sas_scsih_sas_device_find_by_sas_address(struct MPT2SAS_ADAPTER *ioc,
> > +mpt2sas_get_sdev_by_addr(struct MPT2SAS_ADAPTER *ioc,
> >      u64 sas_address)
> >  {
> >         struct _sas_device *sas_device;
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> > +                       sas_address);
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +
> > +       return sas_device;
> > +}
> > +
> > +static struct _sas_device *
> > +__mpt2sas_get_sdev_by_handle(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> > +{
> > +       struct _sas_device *sas_device;
> > +
> > +       assert_spin_locked(&ioc->sas_device_lock);
> >
> >         list_for_each_entry(sas_device, &ioc->sas_device_list, list)
> > -               if (sas_device->sas_address == sas_address)
> > -                       return sas_device;
> > +               if (sas_device->handle == handle)
> > +                       goto found_device;
> >
> >         list_for_each_entry(sas_device, &ioc->sas_device_init_list, list)
> > -               if (sas_device->sas_address == sas_address)
> > -                       return sas_device;
> > +               if (sas_device->handle == handle)
> > +                       goto found_device;
> >
> >         return NULL;
> > +
> > +found_device:
> > +       sas_device_get(sas_device);
> > +       return sas_device;
> >  }
> >
> >  /**
> > - * _scsih_sas_device_find_by_handle - sas device search
> > + * mpt2sas_get_sdev_by_handle - sas device search
> >   * @ioc: per adapter object
> >   * @handle: sas device handle (assigned by firmware)
> >   * Context: Calling function should acquire ioc->sas_device_lock
> > @@ -562,19 +635,16 @@ mpt2sas_scsih_sas_device_find_by_sas_address(struct MPT2SAS_ADAPTER *ioc,
> >   * object.
> >   */
> >  static struct _sas_device *
> > -_scsih_sas_device_find_by_handle(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> > +mpt2sas_get_sdev_by_handle(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >  {
> >         struct _sas_device *sas_device;
> > +       unsigned long flags;
> >
> > -       list_for_each_entry(sas_device, &ioc->sas_device_list, list)
> > -               if (sas_device->handle == handle)
> > -                       return sas_device;
> > -
> > -       list_for_each_entry(sas_device, &ioc->sas_device_init_list, list)
> > -               if (sas_device->handle == handle)
> > -                       return sas_device;
> > +       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +       sas_device = __mpt2sas_get_sdev_by_handle(ioc, handle);
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> > -       return NULL;
> > +       return sas_device;
> >  }
> >
> >  /**
> > @@ -583,7 +653,7 @@ _scsih_sas_device_find_by_handle(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >   * @sas_device: the sas_device object
> >   * Context: This function will acquire ioc->sas_device_lock.
> >   *
> > - * Removing object and freeing associated memory from the ioc->sas_device_list.
> > + * If sas_device is on the list, remove it and decrement its reference count.
> >   */
> >  static void
> >  _scsih_sas_device_remove(struct MPT2SAS_ADAPTER *ioc,
> > @@ -594,9 +664,15 @@ _scsih_sas_device_remove(struct MPT2SAS_ADAPTER *ioc,
> >         if (!sas_device)
> >                 return;
> >
> > +       /*
> > +        * The lock serializes access to the list, but we still need to verify
> > +        * that nobody removed the entry while we were waiting on the lock.
> > +        */
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       list_del(&sas_device->list);
> > -       kfree(sas_device);
> > +       if (!list_empty(&sas_device->list)) {
> > +               list_del_init(&sas_device->list);
> > +               sas_device_put(sas_device);
> > +       }
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >  }
> >
> > @@ -620,6 +696,7 @@ _scsih_sas_device_add(struct MPT2SAS_ADAPTER *ioc,
> >             sas_device->handle, (unsigned long long)sas_device->sas_address));
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +       sas_device_get(sas_device);
> 
> [Sreekanth] I think here we are unnecessarily taking extra reference count,
>  already devices reference count is initialized to one in
> _scsih_add_device() using kref_init() API.

The reference here is for the list itself. The corresponding put() is in
_scsih_sas_device_remove().

> >         list_add_tail(&sas_device->list, &ioc->sas_device_list);
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> > @@ -659,6 +736,7 @@ _scsih_sas_device_init_add(struct MPT2SAS_ADAPTER *ioc,
> >             sas_device->handle, (unsigned long long)sas_device->sas_address));
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +       sas_device_get(sas_device);
> 
> [Sreekanth] same as above comment.

Again, this is a reference for the list. The corresponding put() happens
in sas_device_make_active(), or in _scsih_sas_device_remove() if
mpt2sas_transport_port_add() fails in _scsih_probe_sas().

> >         list_add_tail(&sas_device->list, &ioc->sas_device_init_list);
> >         _scsih_determine_boot_device(ioc, sas_device, 0);
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > @@ -1208,12 +1286,14 @@ _scsih_change_queue_depth(struct scsi_device *sdev, int qdepth)
> >                 goto not_sata;
> >         if ((sas_target_priv_data->flags & MPT_TARGET_FLAGS_VOLUME))
> >                 goto not_sata;
> > +
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -          sas_device_priv_data->sas_target->sas_address);
> > -       if (sas_device && sas_device->device_info &
> > -           MPI2_SAS_DEVICE_INFO_SATA_DEVICE)
> > +       sas_device = __mpt2sas_get_sdev_from_target(ioc, sas_target_priv_data);
> > +       if (sas_device && sas_device->device_info
> > +                       & MPI2_SAS_DEVICE_INFO_SATA_DEVICE) {
> >                 max_depth = MPT2SAS_SATA_QUEUE_DEPTH;
> > +               sas_device_put(sas_device);
> 
> [Sreekanth] Here it looks it is reducing the reference count only for
> SATA drives,
> what if device is of SAS device.

Yeah, you're right. Will fix.

> > +       }
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> >   not_sata:
> > @@ -1271,18 +1351,20 @@ _scsih_target_alloc(struct scsi_target *starget)
> >         /* sas/sata devices */
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> >         rphy = dev_to_rphy(starget->dev.parent);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >            rphy->identify.sas_address);
> >
> >         if (sas_device) {
> >                 sas_target_priv_data->handle = sas_device->handle;
> >                 sas_target_priv_data->sas_address = sas_device->sas_address;
> > +               sas_target_priv_data->sdev = sas_device;
> >                 sas_device->starget = starget;
> >                 sas_device->id = starget->id;
> >                 sas_device->channel = starget->channel;
> >                 if (test_bit(sas_device->handle, ioc->pd_handles))
> >                         sas_target_priv_data->flags |=
> >                             MPT_TARGET_FLAGS_RAID_COMPONENT;
> > +
> 
> [Sreekanth] I think here, sas_device_put() call is missing.

The reference here is for the pointer to the sas_device in the
->hostdata.

However, the corresponding put() is missing in _scsih_target_destroy(),
so it's definitely confusing. I'll fix that.

> >         }
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> > @@ -1324,13 +1406,14 @@ _scsih_target_destroy(struct scsi_target *starget)
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> >         rphy = dev_to_rphy(starget->dev.parent);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -          rphy->identify.sas_address);
> > +       sas_device = __mpt2sas_get_sdev_from_target(ioc, sas_target_priv_data);
> >         if (sas_device && (sas_device->starget == starget) &&
> >             (sas_device->id == starget->id) &&
> >             (sas_device->channel == starget->channel))
> >                 sas_device->starget = NULL;
> >
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> >   out:
> > @@ -1386,7 +1469,7 @@ _scsih_slave_alloc(struct scsi_device *sdev)
> >
> >         if (!(sas_target_priv_data->flags & MPT_TARGET_FLAGS_VOLUME)) {
> >                 spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +               sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >                                 sas_target_priv_data->sas_address);
> >                 if (sas_device && (sas_device->starget == NULL)) {
> >                         sdev_printk(KERN_INFO, sdev,
> > @@ -1394,6 +1477,10 @@ _scsih_slave_alloc(struct scsi_device *sdev)
> >                              __func__, __LINE__);
> >                         sas_device->starget = starget;
> >                 }
> > +
> > +               if (sas_device)
> > +                       sas_device_put(sas_device);
> > +
> >                 spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         }
> >
> > @@ -1428,10 +1515,13 @@ _scsih_slave_destroy(struct scsi_device *sdev)
> >
> >         if (!(sas_target_priv_data->flags & MPT_TARGET_FLAGS_VOLUME)) {
> >                 spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -                  sas_target_priv_data->sas_address);
> > +               sas_device = __mpt2sas_get_sdev_from_target(ioc,
> > +                               sas_target_priv_data);
> >                 if (sas_device && !sas_target_priv_data->num_luns)
> >                         sas_device->starget = NULL;
> > +
> > +               if (sas_device)
> > +                       sas_device_put(sas_device);
> >                 spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         }
> >
> > @@ -2078,7 +2168,7 @@ _scsih_slave_configure(struct scsi_device *sdev)
> >         }
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >            sas_device_priv_data->sas_target->sas_address);
> >         if (!sas_device) {
> >                 spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > @@ -2112,17 +2202,18 @@ _scsih_slave_configure(struct scsi_device *sdev)
> >             (unsigned long long) sas_device->enclosure_logical_id,
> >             sas_device->slot);
> >
> > +       sas_device_put(sas_device);
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         if (!ssp_target)
> >                 _scsih_display_sata_capabilities(ioc, handle, sdev);
> >
> > -
> >         _scsih_change_queue_depth(sdev, qdepth);
> >
> >         if (ssp_target) {
> >                 sas_read_port_mode_page(sdev);
> >                 _scsih_enable_tlr(ioc, sdev);
> >         }
> > +
> >         return 0;
> >  }
> >
> > @@ -2509,8 +2600,7 @@ _scsih_tm_display_info(struct MPT2SAS_ADAPTER *ioc, struct scsi_cmnd *scmd)
> >                     device_str, (unsigned long long)priv_target->sas_address);
> >         } else {
> >                 spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -                   priv_target->sas_address);
> > +               sas_device = __mpt2sas_get_sdev_from_target(ioc, priv_target);
> >                 if (sas_device) {
> >                         if (priv_target->flags &
> >                             MPT_TARGET_FLAGS_RAID_COMPONENT) {
> > @@ -2529,6 +2619,8 @@ _scsih_tm_display_info(struct MPT2SAS_ADAPTER *ioc, struct scsi_cmnd *scmd)
> >                             "enclosure_logical_id(0x%016llx), slot(%d)\n",
> >                            (unsigned long long)sas_device->enclosure_logical_id,
> >                             sas_device->slot);
> > +
> > +                       sas_device_put(sas_device);
> >                 }
> >                 spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         }
> > @@ -2604,12 +2696,12 @@ _scsih_dev_reset(struct scsi_cmnd *scmd)
> >  {
> >         struct MPT2SAS_ADAPTER *ioc = shost_priv(scmd->device->host);
> >         struct MPT2SAS_DEVICE *sas_device_priv_data;
> > -       struct _sas_device *sas_device;
> > -       unsigned long flags;
> > +       struct _sas_device *sas_device = NULL;
> >         u16     handle;
> >         int r;
> >
> >         struct scsi_target *starget = scmd->device->sdev_target;
> > +       struct MPT2SAS_TARGET *target_priv_data = starget->hostdata;
> >
> >         starget_printk(KERN_INFO, starget, "attempting device reset! "
> >             "scmd(%p)\n", scmd);
> > @@ -2629,12 +2721,10 @@ _scsih_dev_reset(struct scsi_cmnd *scmd)
> >         handle = 0;
> >         if (sas_device_priv_data->sas_target->flags &
> >             MPT_TARGET_FLAGS_RAID_COMPONENT) {
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = _scsih_sas_device_find_by_handle(ioc,
> > -                  sas_device_priv_data->sas_target->handle);
> > +               sas_device = mpt2sas_get_sdev_from_target(ioc,
> > +                               target_priv_data);
> >                 if (sas_device)
> >                         handle = sas_device->volume_handle;
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         } else
> >                 handle = sas_device_priv_data->sas_target->handle;
> >
> > @@ -2651,6 +2741,10 @@ _scsih_dev_reset(struct scsi_cmnd *scmd)
> >   out:
> >         sdev_printk(KERN_INFO, scmd->device, "device reset: %s scmd(%p)\n",
> >             ((r == SUCCESS) ? "SUCCESS" : "FAILED"), scmd);
> > +
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> > +
> >         return r;
> >  }
> >
> > @@ -2665,11 +2759,11 @@ _scsih_target_reset(struct scsi_cmnd *scmd)
> >  {
> >         struct MPT2SAS_ADAPTER *ioc = shost_priv(scmd->device->host);
> >         struct MPT2SAS_DEVICE *sas_device_priv_data;
> > -       struct _sas_device *sas_device;
> > -       unsigned long flags;
> > +       struct _sas_device *sas_device = NULL;
> >         u16     handle;
> >         int r;
> >         struct scsi_target *starget = scmd->device->sdev_target;
> > +       struct MPT2SAS_TARGET *target_priv_data = starget->hostdata;
> >
> >         starget_printk(KERN_INFO, starget, "attempting target reset! "
> >             "scmd(%p)\n", scmd);
> > @@ -2689,12 +2783,10 @@ _scsih_target_reset(struct scsi_cmnd *scmd)
> >         handle = 0;
> >         if (sas_device_priv_data->sas_target->flags &
> >             MPT_TARGET_FLAGS_RAID_COMPONENT) {
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = _scsih_sas_device_find_by_handle(ioc,
> > -                  sas_device_priv_data->sas_target->handle);
> > +               sas_device = mpt2sas_get_sdev_from_target(ioc,
> > +                               target_priv_data);
> >                 if (sas_device)
> >                         handle = sas_device->volume_handle;
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         } else
> >                 handle = sas_device_priv_data->sas_target->handle;
> >
> > @@ -2711,6 +2803,10 @@ _scsih_target_reset(struct scsi_cmnd *scmd)
> >   out:
> >         starget_printk(KERN_INFO, starget, "target reset: %s scmd(%p)\n",
> >             ((r == SUCCESS) ? "SUCCESS" : "FAILED"), scmd);
> > +
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> > +
> >         return r;
> >  }
> >
> > @@ -3002,15 +3098,15 @@ _scsih_block_io_to_children_attached_to_ex(struct MPT2SAS_ADAPTER *ioc,
> >
> >         list_for_each_entry(mpt2sas_port,
> >            &sas_expander->sas_port_list, port_list) {
> > -               if (mpt2sas_port->remote_identify.device_type ==
> > -                   SAS_END_DEVICE) {
> > +               if (mpt2sas_port->remote_identify.device_type == SAS_END_DEVICE) {
> >                         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -                       sas_device =
> > -                           mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -                          mpt2sas_port->remote_identify.sas_address);
> > -                       if (sas_device)
> > +                       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> > +                                       mpt2sas_port->remote_identify.sas_address);
> > +                       if (sas_device) {
> >                                 set_bit(sas_device->handle,
> > -                                   ioc->blocking_handles);
> > +                                               ioc->blocking_handles);
> > +                               sas_device_put(sas_device);
> > +                       }
> >                         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >                 }
> >         }
> > @@ -3080,7 +3176,7 @@ _scsih_tm_tr_send(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >  {
> >         Mpi2SCSITaskManagementRequest_t *mpi_request;
> >         u16 smid;
> > -       struct _sas_device *sas_device;
> > +       struct _sas_device *sas_device = NULL;
> >         struct MPT2SAS_TARGET *sas_target_priv_data = NULL;
> >         u64 sas_address = 0;
> >         unsigned long flags;
> > @@ -3110,7 +3206,7 @@ _scsih_tm_tr_send(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >                 return;
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > +       sas_device = __mpt2sas_get_sdev_by_handle(ioc, handle);
> >         if (sas_device && sas_device->starget &&
> >              sas_device->starget->hostdata) {
> >                 sas_target_priv_data = sas_device->starget->hostdata;
> > @@ -3131,14 +3227,14 @@ _scsih_tm_tr_send(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >         if (!smid) {
> >                 delayed_tr = kzalloc(sizeof(*delayed_tr), GFP_ATOMIC);
> >                 if (!delayed_tr)
> > -                       return;
> > +                       goto out;
> >                 INIT_LIST_HEAD(&delayed_tr->list);
> >                 delayed_tr->handle = handle;
> >                 list_add_tail(&delayed_tr->list, &ioc->delayed_tr_list);
> >                 dewtprintk(ioc, printk(MPT2SAS_INFO_FMT
> >                     "DELAYED:tr:handle(0x%04x), (open)\n",
> >                     ioc->name, handle));
> > -               return;
> > +               goto out;
> >         }
> >
> >         dewtprintk(ioc, printk(MPT2SAS_INFO_FMT "tr_send:handle(0x%04x), "
> > @@ -3150,6 +3246,9 @@ _scsih_tm_tr_send(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >         mpi_request->DevHandle = cpu_to_le16(handle);
> >         mpi_request->TaskType = MPI2_SCSITASKMGMT_TASKTYPE_TARGET_RESET;
> >         mpt2sas_base_put_smid_hi_priority(ioc, smid);
> > +out:
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> >  }
> >
> >
> > @@ -4068,7 +4167,6 @@ _scsih_scsi_ioc_info(struct MPT2SAS_ADAPTER *ioc, struct scsi_cmnd *scmd,
> >         char *desc_scsi_state = ioc->tmp_string;
> >         u32 log_info = le32_to_cpu(mpi_reply->IOCLogInfo);
> >         struct _sas_device *sas_device = NULL;
> > -       unsigned long flags;
> >         struct scsi_target *starget = scmd->device->sdev_target;
> >         struct MPT2SAS_TARGET *priv_target = starget->hostdata;
> >         char *device_str = NULL;
> > @@ -4200,9 +4298,7 @@ _scsih_scsi_ioc_info(struct MPT2SAS_ADAPTER *ioc, struct scsi_cmnd *scmd,
> >                 printk(MPT2SAS_WARN_FMT "\t%s wwid(0x%016llx)\n", ioc->name,
> >                     device_str, (unsigned long long)priv_target->sas_address);
> >         } else {
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -                   priv_target->sas_address);
> > +               sas_device = mpt2sas_get_sdev_from_target(ioc, priv_target);
> >                 if (sas_device) {
> >                         printk(MPT2SAS_WARN_FMT "\tsas_address(0x%016llx), "
> >                             "phy(%d)\n", ioc->name, sas_device->sas_address,
> > @@ -4211,8 +4307,9 @@ _scsih_scsi_ioc_info(struct MPT2SAS_ADAPTER *ioc, struct scsi_cmnd *scmd,
> >                             "\tenclosure_logical_id(0x%016llx), slot(%d)\n",
> >                             ioc->name, sas_device->enclosure_logical_id,
> >                             sas_device->slot);
> > +
> > +                       sas_device_put(sas_device);
> >                 }
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         }
> >
> >         printk(MPT2SAS_WARN_FMT "\thandle(0x%04x), ioc_status(%s)(0x%04x), "
> > @@ -4259,7 +4356,7 @@ _scsih_turn_on_pfa_led(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >         Mpi2SepRequest_t mpi_request;
> >         struct _sas_device *sas_device;
> >
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > +       sas_device = mpt2sas_get_sdev_by_handle(ioc, handle);
> >         if (!sas_device)
> >                 return;
> >
> > @@ -4274,7 +4371,7 @@ _scsih_turn_on_pfa_led(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >             &mpi_request)) != 0) {
> >                 printk(MPT2SAS_ERR_FMT "failure at %s:%d/%s()!\n", ioc->name,
> >                 __FILE__, __LINE__, __func__);
> > -               return;
> > +               goto out;
> >         }
> >         sas_device->pfa_led_on = 1;
> >
> > @@ -4284,8 +4381,10 @@ _scsih_turn_on_pfa_led(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >                  "enclosure_processor: ioc_status (0x%04x), loginfo(0x%08x)\n",
> >                  ioc->name, le16_to_cpu(mpi_reply.IOCStatus),
> >                  le32_to_cpu(mpi_reply.IOCLogInfo)));
> > -               return;
> > +               goto out;
> >         }
> > +out:
> > +       sas_device_put(sas_device);
> >  }
> >
> >  /**
> > @@ -4370,19 +4469,17 @@ _scsih_smart_predicted_fault(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >
> >         /* only handle non-raid devices */
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > +       sas_device = __mpt2sas_get_sdev_by_handle(ioc, handle);
> >         if (!sas_device) {
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > +               goto out_unlock;
> >         }
> >         starget = sas_device->starget;
> >         sas_target_priv_data = starget->hostdata;
> >
> >         if ((sas_target_priv_data->flags & MPT_TARGET_FLAGS_RAID_COMPONENT) ||
> > -          ((sas_target_priv_data->flags & MPT_TARGET_FLAGS_VOLUME))) {
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > -       }
> > +          ((sas_target_priv_data->flags & MPT_TARGET_FLAGS_VOLUME)))
> > +               goto out_unlock;
> > +
> >         starget_printk(KERN_WARNING, starget, "predicted fault\n");
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> > @@ -4396,7 +4493,7 @@ _scsih_smart_predicted_fault(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >         if (!event_reply) {
> >                 printk(MPT2SAS_ERR_FMT "failure at %s:%d/%s()!\n",
> >                     ioc->name, __FILE__, __LINE__, __func__);
> > -               return;
> > +               goto out;
> >         }
> >
> >         event_reply->Function = MPI2_FUNCTION_EVENT_NOTIFICATION;
> > @@ -4413,6 +4510,14 @@ _scsih_smart_predicted_fault(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >         event_data->SASAddress = cpu_to_le64(sas_target_priv_data->sas_address);
> >         mpt2sas_ctl_add_to_event_log(ioc, event_reply);
> >         kfree(event_reply);
> > +out:
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> > +       return;
> > +
> > +out_unlock:
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +       goto out;
> >  }
> >
> >  /**
> > @@ -5148,14 +5253,13 @@ _scsih_check_device(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> >         sas_address = le64_to_cpu(sas_device_pg0.SASAddress);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >             sas_address);
> >
> >         if (!sas_device) {
> >                 printk(MPT2SAS_ERR_FMT "device is not present "
> >                     "handle(0x%04x), no sas_device!!!\n", ioc->name, handle);
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > +               goto out_unlock;
> >         }
> >
> >         if (unlikely(sas_device->handle != handle)) {
> > @@ -5172,19 +5276,22 @@ _scsih_check_device(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >             MPI2_SAS_DEVICE0_FLAGS_DEVICE_PRESENT)) {
> >                 printk(MPT2SAS_ERR_FMT "device is not present "
> >                     "handle(0x%04x), flags!!!\n", ioc->name, handle);
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > +               goto out_unlock;
> >         }
> >
> >         /* check if there were any issues with discovery */
> >         if (_scsih_check_access_status(ioc, sas_address, handle,
> > -           sas_device_pg0.AccessStatus)) {
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > -       }
> > +           sas_device_pg0.AccessStatus))
> > +               goto out_unlock;
> > +
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         _scsih_ublock_io_device(ioc, sas_address);
> > +       return;
> 
> [Sreekanth] I think here driver exits from this function without
> reducing the reference count.

Yes, it does. Will fix.

> >
> > +out_unlock:
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> >  }
> >
> >  /**
> > @@ -5208,7 +5315,6 @@ _scsih_add_device(struct MPT2SAS_ADAPTER *ioc, u16 handle, u8 phy_num, u8 is_pd)
> >         u32 ioc_status;
> >         __le64 sas_address;
> >         u32 device_info;
> > -       unsigned long flags;
> >
> >         if ((mpt2sas_config_get_sas_device_pg0(ioc, &mpi_reply, &sas_device_pg0,
> >             MPI2_SAS_DEVICE_PGAD_FORM_HANDLE, handle))) {
> > @@ -5250,14 +5356,13 @@ _scsih_add_device(struct MPT2SAS_ADAPTER *ioc, u16 handle, u8 phy_num, u8 is_pd)
> >                 return -1;
> >         }
> >
> > -
> > -       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = mpt2sas_get_sdev_by_addr(ioc,
> >             sas_address);
> > -       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >
> > -       if (sas_device)
> > +       if (sas_device) {
> > +               sas_device_put(sas_device);
> >                 return 0;
> > +       }
> >
> >         sas_device = kzalloc(sizeof(struct _sas_device),
> >             GFP_KERNEL);
> > @@ -5267,6 +5372,7 @@ _scsih_add_device(struct MPT2SAS_ADAPTER *ioc, u16 handle, u8 phy_num, u8 is_pd)
> >                 return -1;
> >         }
> >
> > +       kref_init(&sas_device->refcount);
> >         sas_device->handle = handle;
> >         if (_scsih_get_sas_address(ioc, le16_to_cpu
> >                 (sas_device_pg0.ParentDevHandle),
> > @@ -5344,7 +5450,6 @@ _scsih_remove_device(struct MPT2SAS_ADAPTER *ioc,
> >             "handle(0x%04x), sas_addr(0x%016llx)\n", ioc->name, __func__,
> >             sas_device->handle, (unsigned long long)
> >             sas_device->sas_address));
> > -       kfree(sas_device);
> >  }
> >  /**
> >   * _scsih_device_remove_by_handle - removing device object by handle
> > @@ -5363,12 +5468,17 @@ _scsih_device_remove_by_handle(struct MPT2SAS_ADAPTER *ioc, u16 handle)
> >                 return;
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > -       if (sas_device)
> > -               list_del(&sas_device->list);
> > +       sas_device = __mpt2sas_get_sdev_by_handle(ioc, handle);
> > +       if (sas_device) {
> > +               list_del_init(&sas_device->list);
> > +               sas_device_put(sas_device);
> > +       }
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -       if (sas_device)
> > +
> > +       if (sas_device) {
> >                 _scsih_remove_device(ioc, sas_device);
> > +               sas_device_put(sas_device);
> > +       }
> >  }
> >
> >  /**
> > @@ -5389,13 +5499,17 @@ mpt2sas_device_remove_by_sas_address(struct MPT2SAS_ADAPTER *ioc,
> >                 return;
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > -           sas_address);
> > -       if (sas_device)
> > -               list_del(&sas_device->list);
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc, sas_address);
> > +       if (sas_device) {
> > +               list_del_init(&sas_device->list);
> > +               sas_device_put(sas_device);
> > +       }
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -       if (sas_device)
> > +
> > +       if (sas_device) {
> >                 _scsih_remove_device(ioc, sas_device);
> > +               sas_device_put(sas_device);
> > +       }
> >  }
> >  #ifdef CONFIG_SCSI_MPT2SAS_LOGGING
> >  /**
> > @@ -5716,26 +5830,28 @@ _scsih_sas_device_status_change_event(struct MPT2SAS_ADAPTER *ioc,
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> >         sas_address = le64_to_cpu(event_data->SASAddress);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >             sas_address);
> >
> > -       if (!sas_device || !sas_device->starget) {
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > -       }
> > +       if (!sas_device || !sas_device->starget)
> > +               goto out;
> >
> >         target_priv_data = sas_device->starget->hostdata;
> > -       if (!target_priv_data) {
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               return;
> > -       }
> > +       if (!target_priv_data)
> > +               goto out;
> >
> >         if (event_data->ReasonCode ==
> >             MPI2_EVENT_SAS_DEV_STAT_RC_INTERNAL_DEVICE_RESET)
> >                 target_priv_data->tm_busy = 1;
> >         else
> >                 target_priv_data->tm_busy = 0;
> > +
> > +out:
> > +       if (sas_device)
> > +               sas_device_put(sas_device);
> > +
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +
> >  }
> >
> >  #ifdef CONFIG_SCSI_MPT2SAS_LOGGING
> > @@ -6123,7 +6239,7 @@ _scsih_sas_pd_expose(struct MPT2SAS_ADAPTER *ioc,
> >         u16 handle = le16_to_cpu(element->PhysDiskDevHandle);
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > +       sas_device = __mpt2sas_get_sdev_by_handle(ioc, handle);
> >         if (sas_device) {
> >                 sas_device->volume_handle = 0;
> >                 sas_device->volume_wwid = 0;
> > @@ -6142,6 +6258,8 @@ _scsih_sas_pd_expose(struct MPT2SAS_ADAPTER *ioc,
> >         /* exposing raid component */
> >         if (starget)
> >                 starget_for_each_device(starget, NULL, _scsih_reprobe_lun);
> > +
> > +       sas_device_put(sas_device);
> >  }
> >
> >  /**
> > @@ -6170,7 +6288,7 @@ _scsih_sas_pd_hide(struct MPT2SAS_ADAPTER *ioc,
> >                     &volume_wwid);
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > +       sas_device = __mpt2sas_get_sdev_by_handle(ioc, handle);
> >         if (sas_device) {
> >                 set_bit(handle, ioc->pd_handles);
> >                 if (sas_device->starget && sas_device->starget->hostdata) {
> > @@ -6189,6 +6307,8 @@ _scsih_sas_pd_hide(struct MPT2SAS_ADAPTER *ioc,
> >         /* hiding raid component */
> >         if (starget)
> >                 starget_for_each_device(starget, (void *)1, _scsih_reprobe_lun);
> > +
> > +       sas_device_put(sas_device);
> >  }
> >
> >  /**
> > @@ -6221,7 +6341,6 @@ _scsih_sas_pd_add(struct MPT2SAS_ADAPTER *ioc,
> >      Mpi2EventIrConfigElement_t *element)
> >  {
> >         struct _sas_device *sas_device;
> > -       unsigned long flags;
> >         u16 handle = le16_to_cpu(element->PhysDiskDevHandle);
> >         Mpi2ConfigReply_t mpi_reply;
> >         Mpi2SasDevicePage0_t sas_device_pg0;
> > @@ -6231,11 +6350,11 @@ _scsih_sas_pd_add(struct MPT2SAS_ADAPTER *ioc,
> >
> >         set_bit(handle, ioc->pd_handles);
> >
> > -       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > -       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -       if (sas_device)
> > +       sas_device = mpt2sas_get_sdev_by_handle(ioc, handle);
> > +       if (sas_device) {
> > +               sas_device_put(sas_device);
> >                 return;
> > +       }
> >
> >         if ((mpt2sas_config_get_sas_device_pg0(ioc, &mpi_reply, &sas_device_pg0,
> >             MPI2_SAS_DEVICE_PGAD_FORM_HANDLE, handle))) {
> > @@ -6509,7 +6628,6 @@ _scsih_sas_ir_physical_disk_event(struct MPT2SAS_ADAPTER *ioc,
> >         u16 handle, parent_handle;
> >         u32 state;
> >         struct _sas_device *sas_device;
> > -       unsigned long flags;
> >         Mpi2ConfigReply_t mpi_reply;
> >         Mpi2SasDevicePage0_t sas_device_pg0;
> >         u32 ioc_status;
> > @@ -6542,12 +6660,11 @@ _scsih_sas_ir_physical_disk_event(struct MPT2SAS_ADAPTER *ioc,
> >                 if (!ioc->is_warpdrive)
> >                         set_bit(handle, ioc->pd_handles);
> >
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -
> > -               if (sas_device)
> > +               sas_device = mpt2sas_get_sdev_by_handle(ioc, handle);
> > +               if (sas_device) {
> > +                       sas_device_put(sas_device);
> >                         return;
> > +               }
> >
> >                 if ((mpt2sas_config_get_sas_device_pg0(ioc, &mpi_reply,
> >                     &sas_device_pg0, MPI2_SAS_DEVICE_PGAD_FORM_HANDLE,
> > @@ -7015,6 +7132,7 @@ _scsih_remove_unresponding_sas_devices(struct MPT2SAS_ADAPTER *ioc)
> >         struct _raid_device *raid_device, *raid_device_next;
> >         struct list_head tmp_list;
> >         unsigned long flags;
> > +       LIST_HEAD(head);
> >
> >         printk(MPT2SAS_INFO_FMT "removing unresponding devices: start\n",
> >             ioc->name);
> > @@ -7022,14 +7140,29 @@ _scsih_remove_unresponding_sas_devices(struct MPT2SAS_ADAPTER *ioc)
> >         /* removing unresponding end devices */
> >         printk(MPT2SAS_INFO_FMT "removing unresponding devices: end-devices\n",
> >             ioc->name);
> > +
> > +       /*
> > +        * Iterate, pulling off devices marked as non-responding. We become the
> > +        * owner for the reference the list had on any object we prune.
> > +        */
> > +       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> >         list_for_each_entry_safe(sas_device, sas_device_next,
> > -           &ioc->sas_device_list, list) {
> > +                       &ioc->sas_device_list, list) {
> >                 if (!sas_device->responding)
> > -                       mpt2sas_device_remove_by_sas_address(ioc,
> > -                               sas_device->sas_address);
> > +                       list_move_tail(&sas_device->list, &head);
> >                 else
> >                         sas_device->responding = 0;
> >         }
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +
> > +       /*
> > +        * Now, uninitialize and remove the unresponding devices we pruned.
> > +        */
> > +       list_for_each_entry_safe(sas_device, sas_device_next, &head, list) {
> > +               _scsih_remove_device(ioc, sas_device);
> > +               list_del_init(&sas_device->list);
> > +               sas_device_put(sas_device);
> > +       }
> >
> >         /* removing unresponding volumes */
> >         if (ioc->ir_firmware) {
> > @@ -7179,11 +7312,11 @@ _scsih_scan_for_devices_after_reset(struct MPT2SAS_ADAPTER *ioc)
> >                 }
> >                 phys_disk_num = pd_pg0.PhysDiskNum;
> >                 handle = le16_to_cpu(pd_pg0.DevHandle);
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = _scsih_sas_device_find_by_handle(ioc, handle);
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               if (sas_device)
> > +               sas_device = mpt2sas_get_sdev_by_handle(ioc, handle);
> > +               if (sas_device) {
> > +                       sas_device_put(sas_device);
> >                         continue;
> > +               }
> >                 if (mpt2sas_config_get_sas_device_pg0(ioc, &mpi_reply,
> >                     &sas_device_pg0, MPI2_SAS_DEVICE_PGAD_FORM_HANDLE,
> >                     handle) != 0)
> > @@ -7302,12 +7435,12 @@ _scsih_scan_for_devices_after_reset(struct MPT2SAS_ADAPTER *ioc)
> >                 if (!(_scsih_is_end_device(
> >                     le32_to_cpu(sas_device_pg0.DeviceInfo))))
> >                         continue;
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +               sas_device = mpt2sas_get_sdev_by_addr(ioc,
> >                     le64_to_cpu(sas_device_pg0.SASAddress));
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > -               if (sas_device)
> > +               if (sas_device) {
> > +                       sas_device_put(sas_device);
> >                         continue;
> > +               }
> >                 parent_handle = le16_to_cpu(sas_device_pg0.ParentDevHandle);
> >                 if (!_scsih_get_sas_address(ioc, parent_handle, &sas_address)) {
> >                         printk(MPT2SAS_INFO_FMT "\tBEFORE adding end device: "
> > @@ -7966,6 +8099,48 @@ _scsih_probe_raid(struct MPT2SAS_ADAPTER *ioc)
> >         }
> >  }
> >
> > +static struct _sas_device *get_next_sas_device(struct MPT2SAS_ADAPTER *ioc)
> > +{
> > +       struct _sas_device *sas_device = NULL;
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +       if (!list_empty(&ioc->sas_device_init_list)) {
> > +               sas_device = list_first_entry(&ioc->sas_device_init_list,
> > +                               struct _sas_device, list);
> > +               sas_device_get(sas_device);
> > +       }
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +
> > +       return sas_device;
> > +}
> > +
> > +static void sas_device_make_active(struct MPT2SAS_ADAPTER *ioc,
> > +               struct _sas_device *sas_device)
> > +{
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > +
> > +       /*
> > +        * Since we dropped the lock during the call to port_add(), we need to
> > +        * be careful here that somebody else didn't move or delete this item
> > +        * while we were busy with other things.
> > +        *
> > +        * If it was on the list, we need a put() for the reference the list
> > +        * had. Either way, we need a get() for the destination list.
> > +        */
> > +       if (!list_empty(&sas_device->list)) {
> > +               list_del_init(&sas_device->list);
> > +               sas_device_put(sas_device);
> > +       }
> > +
> > +       sas_device_get(sas_device);
> > +       list_add_tail(&sas_device->list, &ioc->sas_device_list);
> > +
> > +       spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +}
> > +
> >  /**
> >   * _scsih_probe_sas - reporting sas devices to sas transport
> >   * @ioc: per adapter object
> > @@ -7975,34 +8150,30 @@ _scsih_probe_raid(struct MPT2SAS_ADAPTER *ioc)
> >  static void
> >  _scsih_probe_sas(struct MPT2SAS_ADAPTER *ioc)
> >  {
> > -       struct _sas_device *sas_device, *next;
> > -       unsigned long flags;
> > -
> > -       /* SAS Device List */
> > -       list_for_each_entry_safe(sas_device, next, &ioc->sas_device_init_list,
> > -           list) {
> > +       struct _sas_device *sas_device;
> >
> > -               if (ioc->hide_drives)
> > -                       continue;
> > +       if (ioc->hide_drives)
> > +               return;
> >
> > +       while ((sas_device = get_next_sas_device(ioc))) {
> >                 if (!mpt2sas_transport_port_add(ioc, sas_device->handle,
> > -                   sas_device->sas_address_parent)) {
> > -                       list_del(&sas_device->list);
> > -                       kfree(sas_device);
> > +                               sas_device->sas_address_parent)) {
> > +                       _scsih_sas_device_remove(ioc, sas_device);
> > +                       sas_device_put(sas_device);
> >                         continue;
> >                 } else if (!sas_device->starget) {
> >                         if (!ioc->is_driver_loading) {
> >                                 mpt2sas_transport_port_remove(ioc,
> > -                                       sas_device->sas_address,
> > -                                       sas_device->sas_address_parent);
> > -                               list_del(&sas_device->list);
> > -                               kfree(sas_device);
> > +                                               sas_device->sas_address,
> > +                                               sas_device->sas_address_parent);
> > +                               _scsih_sas_device_remove(ioc, sas_device);
> > +                               sas_device_put(sas_device);
> >                                 continue;
> >                         }
> >                 }
> > -               spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -               list_move_tail(&sas_device->list, &ioc->sas_device_list);
> > -               spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> > +
> > +               sas_device_make_active(ioc, sas_device);
> > +               sas_device_put(sas_device);
> >         }
> >  }
> >
> > diff --git a/drivers/scsi/mpt2sas/mpt2sas_transport.c b/drivers/scsi/mpt2sas/mpt2sas_transport.c
> > index ff2500a..af86800 100644
> > --- a/drivers/scsi/mpt2sas/mpt2sas_transport.c
> > +++ b/drivers/scsi/mpt2sas/mpt2sas_transport.c
> > @@ -1323,15 +1323,17 @@ _transport_get_enclosure_identifier(struct sas_rphy *rphy, u64 *identifier)
> >         int rc;
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >             rphy->identify.sas_address);
> >         if (sas_device) {
> >                 *identifier = sas_device->enclosure_logical_id;
> >                 rc = 0;
> > +               sas_device_put(sas_device);
> >         } else {
> >                 *identifier = 0;
> >                 rc = -ENXIO;
> >         }
> > +
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         return rc;
> >  }
> > @@ -1351,12 +1353,14 @@ _transport_get_bay_identifier(struct sas_rphy *rphy)
> >         int rc;
> >
> >         spin_lock_irqsave(&ioc->sas_device_lock, flags);
> > -       sas_device = mpt2sas_scsih_sas_device_find_by_sas_address(ioc,
> > +       sas_device = __mpt2sas_get_sdev_by_addr(ioc,
> >             rphy->identify.sas_address);
> > -       if (sas_device)
> > +       if (sas_device) {
> >                 rc = sas_device->slot;
> > -       else
> > +               sas_device_put(sas_device);
> > +       } else {
> >                 rc = -ENXIO;
> > +       }
> >         spin_unlock_irqrestore(&ioc->sas_device_lock, flags);
> >         return rc;
> >  }
> > --
> > 1.8.5.6
> >
> 
> 
> 
> -- 
> 
> Regards,
> Sreekanth