target_submit_cmd_map_sgls() is being removed, so convert xen to the new
submission API. This has it use target_init_cmd(), target_submit_prep(), or
target_submit() because we need to have LIO core map sgls which is now done
in target_submit_prep(). target_init_cmd() will never fail for xen because
it does its own sync during session shutdown, so we can remove that code.

Note: xen never calls target_stop_session() so target_submit_cmd_map_sgls()
never failed (in the new API target_init_cmd() handles
target_stop_session() being called when cmds are being submitted). If it
were to have used target_stop_session() and got an error, we would have hit
a refcount bug like xen and usb, because it does:

    if (rc < 0) {
            transport_send_check_condition_and_sense(se_cmd,
                            TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
            transport_generic_free_cmd(se_cmd, 0);
    }

transport_send_check_condition_and_sense() calls queue_status which calls
scsiback_cmd_done->target_put_sess_cmd. We do an extra
transport_generic_free_cmd() call above which would have dropped the
refcount to -1 and the refcount code would spit out errors.

Link: https://lore.kernel.org/r/20210227170006.5077-13-michael.christie@oracle.comReviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd_map_sgls() is being removed, so convert vhost-scsi to the
new submission API. This has it use target_init_cmd(),
target_submit_prep(), target_submit() because we need to have LIO core map
sgls which is now done in target_submit_prep(), and in the next patches we
will do the target_submit step from the LIO workqueue.

Note: vhost-scsi never calls target_stop_session() so
target_submit_cmd_map_sgls() never failed (in the new API target_init_cmd()
handles target_stop_session() being called when cmds are being
submitted). If it were to have used target_stop_session() and got an error,
we would have hit a refcount bug like xen and usb, because it does:

if (rc < 0) {
	transport_send_check_condition_and_sense(se_cmd,
			TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
	transport_generic_free_cmd(se_cmd, 0);
}

transport_send_check_condition_and_sense() calls queue_status which does
transport_generic_free_cmd(), and then we do an extra
transport_generic_free_cmd() call above which would have dropped the
refcount to -1 and the refcount code would spit out errors.

Link: https://lore.kernel.org/r/20210227170006.5077-12-michael.christie@oracle.com
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd() is now only for simple drivers that do their own sync
during shutdown and do not use target_stop_session(). It will never return
a failure, so we can remove that code from the driver.

Note: Before these patches target_submit_cmd() would never return an error
for usb since it does not use target_stop_session(). If it did then we
would have hit a refcount error here:

    transport_send_check_condition_and_sense(se_cmd,
                             TCM_UNSUPPORTED_SCSI_OPCODE, 1);
    transport_generic_free_cmd(&cmd->se_cmd, 0);

transport_send_check_condition_and_sense() calls queue_status and the
driver can sometimes do transport_generic_free_cmd() from there via
uasp_status_data_cmpl(). In that case, the above
transport_generic_free_cmd() would then hit a refcount error.

So that other use of the above error path in the driver is also probably
wrong, but someone with the hardware needs to fix that.

Link: https://lore.kernel.org/r/20210227170006.5077-11-michael.christie@oracle.com
Cc: Felipe Balbi <balbi@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd() is now only for simple drivers that do their own sync
during shutdown and do not use target_stop_session(). It will never return
a failure, so we can remove that code from the driver.

Link: https://lore.kernel.org/r/20210227170006.5077-10-michael.christie@oracle.com
Cc: Chris Boot <bootc@bootc.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd_map_sgls() is being removed, so convert loop to
the new submission API.

Even though loop does its own shutdown sync, this has loop use
target_init_cmd()/target_submit_prep()/target_submit() since it needed to
map sgls and in the next patches it will use the API to use LIO's
workqueue.

Link: https://lore.kernel.org/r/20210227170006.5077-9-michael.christie@oracle.comTested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd() is now only for simple drivers that do their
own sync during shutdown and do not use target_stop_session().

tcm_qla2xxx uses target_stop_session() to sync session shutdown with LIO
core, so we use target_init_cmd()/target_submit_prep()/target_submit(),
because target_init_cmd() will detect the target_stop_session() call and
return an error.

Link: https://lore.kernel.org/r/20210227170006.5077-8-michael.christie@oracle.com
Cc: Nilesh Javali <njavali@marvell.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd() is now only for simple drivers that do their own sync
during shutdown and do not use target_stop_session(). It will never return
a failure, so we can remove that code from the driver.

Link: https://lore.kernel.org/r/20210227170006.5077-7-michael.christie@oracle.com
Cc: Michael Cyr <mikecyr@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

target_submit_cmd_map_sgls() is being removed, so convert srpt to the new
submission API.

srpt uses target_stop_session() to sync session shutdown with LIO core, so
we use target_init_cmd()/target_submit_prep()/target_submit(), because
target_init_cmd() will detect the target_stop_session() call and return an
error.

Link: https://lore.kernel.org/r/20210227170006.5077-6-michael.christie@oracle.com
Cc: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

This breaks up target_submit_cmd_map_sgls() into 3 helpers:

 - target_init_cmd(): Do the basic general setup and get a refcount to the
   session to make sure the caller can execute the cmd.

 - target_submit_prep(): Do the mapping, cdb processing and get a ref to
   the LUN.

 - target_submit(): Pass the cmd to LIO core for execution.

The above functions must be used by drivers that either:

 1. Rely on LIO for session shutdown synchronization by calling
    target_stop_session().

 2. Need to map sgls.

When the next patches are applied then simple drivers that do not need the
extra functionality above can use target_submit_cmd() and not worry about
failures being returned and how to handle them, since many drivers were
getting this wrong and would have hit refcount bugs.

Also, by breaking target_submit_cmd_map_sgls() up into these 3 helper
functions, we can allow the later patches to do the init/prep from
interrupt context and then do the submission from a workqueue.

Link: https://lore.kernel.org/r/20210227170006.5077-5-michael.christie@oracle.com
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Michael Cyr <mikecyr@linux.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Rename transport_init_se_cmd() to __target_init_cmd() to reflect that it is
more of an internal function that drivers should normally not use and
because we are going to add a new init function in the next patches.

Link: https://lore.kernel.org/r/20210227170006.5077-4-michael.christie@oracle.comReviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The kref_get_unless_zero() use in target_get_sess_cmd() was added in:

    commit 1b4c59b7 ("target: fix potential race window in
    target_sess_cmd_list_waiting()")'

but it does not seem to do anything.

The original patch might have thought we could have added the cmd to the
sess_wait_list and then target_wait_for_sess_cmds could do a put before
target_get_sess_cmd did its get. That wouldn't happen because we do the get
first then grab the sess lock and put it on the list.

It is also not needed now, because the sess_cmd_list does not exist anymore
and we instead wait on the session cmd_count.

The other problem with the commit is that several
target_submit_cmd_map_sgls()/target_submit_cmd() callers do not handle the
error case properly if it were to ever happen. These drivers think they
have their normal refcount on the cmd and in many cases do a
transport_generic_free_cmd() plus target_put_sess_cmd() so they would have
fired off the refcount WARN/BUGs.

This patch just changes the kref_get_unless_zero() to kref_get().

Link: https://lore.kernel.org/r/20210227170006.5077-3-michael.christie@oracle.comTested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Prepare to split target_submit_cmd_map_sgls() so the initialization and
submission part can be called at different times. If the init part fails we
can reference the t_task_cdb early in some of the logging and tracing
code. Move it to transport_init_se_cmd() so we don't hit NULL pointer
crashes.

Link: https://lore.kernel.org/r/20210227170006.5077-2-michael.christie@oracle.comTested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

SCSI currently uses an atomic variable to track queue depth for each
attached device. The queue depth depends on many factors such as transport
type and device implementation. In addition, the SCSI device queue depth is
not a static entity but changes over time as a result of congestion
management.

While blk-mq currently tracks queue depth for each hctx, it can't easily be
changed to accommodate the SCSI per-device requirement.

The current approach of using an atomic variable doesn't scale well when
there are lots of CPU cores and the disk is very fast. IOPS can be
substantially impacted by the atomic in the hot path.

Replace the atomic variable sdev->device_busy with an sbitmap for tracking
the SCSI device queue depth.

It has been observed that IOPS is improved ~30% by this patchset in the
following test:

1) test machine(32 logical CPU cores)
	Thread(s) per core:  2
	Core(s) per socket:  8
	Socket(s):           2
	NUMA node(s):        2
	Model name:          Intel(R) Xeon(R) Silver 4110 CPU @ 2.10GHz

2) setup scsi_debug:
modprobe scsi_debug virtual_gb=128 max_luns=1 submit_queues=32 delay=0 max_queue=256

3) fio script:
fio --rw=randread --size=128G --direct=1 --ioengine=libaio --iodepth=2048 \
	--numjobs=32 --bs=4k --group_reporting=1 --group_reporting=1 --runtime=60 \
	--loops=10000 --name=job1 --filename=/dev/sdN

[mkp: fix device_busy reference in mpt3sas]

Link: https://lore.kernel.org/r/20210122023317.687987-14-ming.lei@redhat.com
Link: https://lore.kernel.org/linux-block/20200119071432.18558-6-ming.lei@redhat.com/
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Limit SCSI device's queue depth to max(host->can_queue, 1024) in
scsi_change_queue_depth(). 1024 is big enough for saturating current fast
SCSI LUN(SSD or RAID volume on multiple SSDs). Also single hardware queue
depth is usually enough for saturating single LUN because per-core
performance is often considered in storage design.

This patch is needed for replacing sdev->device_busy with sbitmap which has
to be pre-allocated with reasonable max depth.

Link: https://lore.kernel.org/r/20210122023317.687987-13-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Add scsi_device_busy() helper to prepare drivers for tracking device queue
depth via sbitmap_queue.

Link: https://lore.kernel.org/r/20210122023317.687987-12-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Use local tracking of per-sdev outstanding command since sdev_busy in SCSI
mid layer is improved for performance reason using sbitmap (earlier it was
atomic variable).

Link: https://lore.kernel.org/r/20210122023317.687987-11-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The following three fields of scsi_host_template are referenced in the SCSI
I/O submission hot path. Put them together in one cacheline:

 - cmd_size

 - queuecommand

 - commit_rqs

Link: https://lore.kernel.org/r/20210122023317.687987-10-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

SCSI uses a global atomic variable to track queue depth for each
LUN/request queue.

This doesn't scale well when there are lots of CPU cores and the disk is
very fast. It has been observed that IOPS is affected a lot by tracking
queue depth via sdev->device_busy in the I/O path.

Return budget token from .get_budget callback. The budget token can be
passed to driver so that we can replace the atomic variable with
sbitmap_queue and alleviate the scaling problems that way.

Link: https://lore.kernel.org/r/20210122023317.687987-9-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Since SCSI is the only driver which requires dispatch budget move the token
from struct request to struct scsi_cmnd.

Link: https://lore.kernel.org/r/20210122023317.687987-8-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Move code for calculating default shift into a public helper which can be
used by SCSI.

Link: https://lore.kernel.org/r/20210122023317.687987-7-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

SCSI's .device_busy will be converted to sbitmap and sbitmap_weight is
needed. Export the helper.

The only existing user of sbitmap_weight() uses it to find out how many
bits are set and not cleared. Align sbitmap_weight() meaning with this
usage model.

Link: https://lore.kernel.org/r/20210122023317.687987-6-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Allocation hint should have belonged to sbitmap. Also, when sbitmap's depth
is high and there is no need to use mulitple wakeup queues, user can
benefit from percpu allocation hint too.

Move allocation hint into sbitmap, then SCSI device queue can benefit from
allocation hint when converting to plain sbitmap.

Convert vhost/scsi.c to use sbitmap allocation with percpu alloc hint. This
is more efficient than the previous approach.

Link: https://lore.kernel.org/r/20210122023317.687987-5-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: virtualization@lists.linux-foundation.org
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Add helpers for updating allocation hint so that we can avoid duplicate
code.

Prepare for moving allocation hint into sbitmap.

Link: https://lore.kernel.org/r/20210122023317.687987-4-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Currently the allocation round_robin info is maintained by sbitmap_queue.

However, bit allocation really belongs to sbitmap. Move it there.

Link: https://lore.kernel.org/r/20210122023317.687987-3-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: virtualization@lists.linux-foundation.org
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

No one uses this helper any more, so kill it.

Link: https://lore.kernel.org/r/20210122023317.687987-2-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

An enabled user-specified exception event that does not clear quickly will
repeatedly cause the handler to run. That could unduly disturb the driver
behaviour being tested or debugged. To prevent that add debugfs file
exception_event_rate_limit_ms. When a exception event happens, it is
disabled, and then after a period of time (default 20ms) the exception
event is enabled again.

Note that if the driver also has that exception event enabled, it will not
be disabled.

Link: https://lore.kernel.org/r/20210209062437.6954-5-adrian.hunter@intel.comAcked-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Allow users to enable specific exception events via debugfs.

The bits enabled by the driver ee_drv_ctrl are separated from the bits
enabled by the user ee_usr_ctrl. The control mask ee_mask_ctrl is the
logical-or of those two. A mutex is needed to ensure that the masks match
what was written to the device.

Link: https://lore.kernel.org/r/20210209062437.6954-4-adrian.hunter@intel.comAcked-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

For readability and completeness, add exception event definitions.

Link: https://lore.kernel.org/r/20210209062437.6954-3-adrian.hunter@intel.comReviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Currently, exception event status can be read from wExceptionEventStatus
attribute (sysfs file attributes/exception_event_status under the UFS host
controller device directory). Polling that attribute to track UFS exception
events is impractical, so add a tracepoint to track exception events for
testing and debugging purposes.

Note, by the time the exception event status is read, the exception event
may have cleared, so the value can be zero - see example below.

Note also, only enabled exception events can be reported. A subsequent
patch adds the ability for users to enable selected exception events via
debugfs.

Example with driver instrumented to enable all exception events:

  # echo 1 > /sys/kernel/debug/tracing/events/ufs/ufshcd_exception_event/enable

  ... do some I/O ...

  # cat /sys/kernel/debug/tracing/trace
  # tracer: nop
  #
  # entries-in-buffer/entries-written: 3/3   #P:5
  #
  #                                _-----=> irqs-off
  #                               / _----=> need-resched
  #                              | / _---=> hardirq/softirq
  #                              || / _--=> preempt-depth
  #                              ||| /     delay
  #           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION
  #              | |         |   ||||      |         |
       kworker/2:2-173     [002] ....   731.486419: ufshcd_exception_event: 0000:00:12.5: status 0x0
       kworker/2:2-173     [002] ....   732.608918: ufshcd_exception_event: 0000:00:12.5: status 0x4
       kworker/2:2-173     [002] ....   732.609312: ufshcd_exception_event: 0000:00:12.5: status 0x4

Link: https://lore.kernel.org/r/20210209062437.6954-2-adrian.hunter@intel.comReviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Pull misc fixes from Jens Axboe:
 "Two misc fixes that don't belong in other branches:

   - Fix a regression with ia64 signals, introduced by the
     TIF_NOTIFY_SIGNAL change in 5.11.

   - Fix the current swapfile regression from this merge window"

* tag 'misc-5.12-2021-03-02' of git://git.kernel.dk/linux-block:
  swap: fix swapfile read/write offset
  ia64: don't call handle_signal() unless there's actually a signal queued

We're not factoring in the start of the file for where to write and
read the swapfile, which leads to very unfortunate side effects of
writing where we should not be...

Fixes: 48d15436 ("mm: remove get_swap_bio")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Sergei and John both reported that ia64 failed to boot in 5.11, and it
was related to signals. Turns out the ia64 signal handling is a bit odd,
it doesn't check the return value of get_signal() for whether there's a
signal to deliver or not. With the introduction of TIF_NOTIFY_SIGNAL,
then task_work could trigger it.

Fix it by only calling handle_signal() if we actually have a real signal
to deliver. This brings it in line with all other archs, too.

Fixes: b269c229 ("ia64: add support for TIF_NOTIFY_SIGNAL")
Reported-by: Sergei Trofimovich <slyich@gmail.com>
Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Tested-by: Sergei Trofimovich <slyich@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Merge branch 'kmap-conversion-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull kmap conversion updates from David Sterba:
 "This contains changes regarding kmap API use and eg conversion from
  kmap_atomic to kmap_local_page.

  The API belongs to memory management but to save cross-tree
  dependency headaches we've agreed to take it through the btrfs tree
  because there are some trivial conversions possible, while the rest
  will need some time and getting the easy cases out of the way would be
  convenient.

  The changes can be grouped:

   - function exports, new helpers

   - new VM_BUG_ON for additional verification; it's been discussed if
     it should be VM_BUG_ON or BUG_ON, the former was chosen due to
     performance reasons

   - code replaced by relevant helpers"

[ This is an updated version of a request that originally came in during
  the merge window, but I asked for some updates:

    https://lore.kernel.org/lkml/cover.1614090658.git.dsterba@suse.com/

  which is why this got merge after the merge window closed.  - Linus ]

* 'kmap-conversion-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: use copy_highpage() instead of 2 kmaps()
  btrfs: use memcpy_[to|from]_page() and kmap_local_page()
  mm/highmem: Add VM_BUG_ON() to mem*_page() calls
  mm/highmem: Introduce memcpy_page(), memmove_page(), and memset_page()
  mm/highmem: Convert memcpy_[to|from]_page() to kmap_local_page()
  mm/highmem: Lift memcpy_[to|from]_page to core

Pull btrfs fixes from David Sterba:
 "This is the first batch of fixes that usually arrive during the merge
  window code freeze. Regressions and stable material.

  Regressions:

   - fix deadlock in log sync in zoned mode

   - fix bugs in subpage mode still wrongly assuming sectorsize == page
     size

  Fixes:

   - fix missing kunmap of the Q stripe in RAID6

   - block group fixes:
      - fix race between extent freeing/allocation when using bitmaps
      - avoid double put of block group when emptying cluster

   - swapfile fixes:
      - fix swapfile writes vs running scrub
      - fix swapfile activation vs snapshot creation

   - fix stale data exposure after cloning a hole with NO_HOLES enabled

   - remove tree-checker check that does not work in case information
     from other leaves is necessary"

* tag 'for-5.12-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: zoned: fix deadlock on log sync
  btrfs: avoid double put of block group when emptying cluster
  btrfs: fix stale data exposure after cloning a hole with NO_HOLES enabled
  btrfs: tree-checker: do not error out if extent ref hash doesn't match
  btrfs: fix race between swap file activation and snapshot creation
  btrfs: fix race between writes to swap files and scrub
  btrfs: avoid checking for RO block group twice during nocow writeback
  btrfs: fix race between extent freeing/allocation when using bitmaps
  btrfs: make check_compressed_csum() to be subpage compatible
  btrfs: make btrfs_submit_compressed_read() subpage compatible
  btrfs: fix raid6 qstripe kmap

Pull ide fix from Jens Axboe:
 "This is a leftover fix from 5.11, where I forgot to ship it your way"

* tag 'ide-5.11-2021-02-28' of git://git.kernel.dk/linux-block:
  ide/falconide: Fix module unload

Merge tag 'kbuild-fixes-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix UNUSED_KSYMS_WHITELIST for Clang LTO

 - Make -s builds really silent irrespective of V= option

 - Fix build error when SUBLEVEL or PATCHLEVEL is empty

* tag 'kbuild-fixes-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: Fix <linux/version.h> for empty SUBLEVEL or PATCHLEVEL again
  kbuild: make -s option take precedence over V=1
  ia64: remove redundant READELF from arch/ia64/Makefile
  kbuild: do not include include/config/auto.conf from adjust_autoksyms.sh
  kbuild: fix UNUSED_KSYMS_WHITELIST for Clang LTO
  kbuild: lto: add _mcount to list of used symbols

Pull arch/csky updates from Guo Ren:
 "Features:
   - add new memory layout 2.5G(user):1.5G(kernel)
   - add kmemleak support
   - reconstruct VDSO framework: add VDSO with GENERIC_GETTIMEOFDAY,
     GENERIC_TIME_VSYSCALL, HAVE_GENERIC_VDSO
   - add faulthandler_disabled() check
   - support (fix) swapon
   - add (fix) _PAGE_ACCESSED for default pgprot
   - abort uaccess retries upon fatal signal (from arm)

  Fixes and optimizations:
   - fix perf probe failure
   - fix show_regs doesn't contain regs->usp
   - remove custom asm/atomic.h implementation
   - fix barrier design
   - fix futex SMP implementation
   - fix asm/cmpxchg.h with correct ordering barrier
   - cleanup asm/spinlock.h
   - fix PTE global for 2.5:1.5 virtual memory
   - remove prologue of page fault handler in entry.S
   - fix TLB maintenance synchronization problem
   - add show_tlb for CPU_CK860 debug
   - fix FAULT_FLAG_XXX param for handle_mm_fault
   - fix update_mmu_cache called with user io mapping
   - fix do_page_fault parent irq status
   - fix a size determination in gpr_get()
   - pgtable.h: Coding convention
   - kprobe: Fix code in simulate without 'long'
   - fix pfn_valid error with wrong max_mapnr
   - use free_initmem_default() in free_initmem()
   - fix compile error"

* tag 'csky-for-linus-5.12-rc1' of git://github.com/c-sky/csky-linux: (30 commits)
  csky: Fixup compile error
  csky: use free_initmem_default() in free_initmem()
  csky: Fixup pfn_valid error with wrong max_mapnr
  csky: Add VDSO with GENERIC_GETTIMEOFDAY, GENERIC_TIME_VSYSCALL, HAVE_GENERIC_VDSO
  csky: kprobe: Fixup code in simulate without 'long'
  csky: Fixup swapon
  csky: pgtable.h: Coding convention
  csky: Fixup _PAGE_ACCESSED for default pgprot
  csky: remove unused including <linux/version.h>
  csky: Fix a size determination in gpr_get()
  csky: Reconstruct VDSO framework
  csky: mm: abort uaccess retries upon fatal signal
  csky: Sync riscv mm/fault.c for easy maintenance
  csky: Fixup do_page_fault parent irq status
  csky: Add faulthandler_disabled() check
  csky: Fixup update_mmu_cache called with user io mapping
  csky: Fixup FAULT_FLAG_XXX param for handle_mm_fault
  csky: Add show_tlb for CPU_CK860 debug
  csky: Fix TLB maintenance synchronization problem
  csky: Add kmemleak support
  ...

Pull more RISC-V updates from Palmer Dabbelt:
 "A pair of patches that slipped through the cracks:

   - enable CPU hotplug in the defconfigs

   - some cleanups to setup_bootmem

  There's also a single fix for some randconfig build failures:

   - make NUMA depend on SMP"

* tag 'riscv-for-linus-5.12-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Cleanup setup_bootmem()
  RISC-V: Enable CPU Hotplug in defconfigs
  RISC-V: Make NUMA depend on SMP

Pull more SCSI updates from James Bottomley:
 "This is a few driver updates (iscsi, mpt3sas) that were still in the
  staging queue when the merge window opened (all committed on or before
  8 Feb) and some small bug fixes which came in during the merge window
  (all committed on 22 Feb)"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (30 commits)
  scsi: hpsa: Correct dev cmds outstanding for retried cmds
  scsi: sd: Fix Opal support
  scsi: target: tcmu: Fix memory leak caused by wrong uio usage
  scsi: target: tcmu: Move some functions without code change
  scsi: sd: sd_zbc: Don't pass GFP_NOIO to kvcalloc
  scsi: aic7xxx: Remove unused function pointer typedef ahc_bus_suspend/resume_t
  scsi: bnx2fc: Fix Kconfig warning & CNIC build errors
  scsi: ufs: Fix a duplicate dev quirk number
  scsi: aic79xx: Fix spelling of version
  scsi: target: core: Prevent underflow for service actions
  scsi: target: core: Add cmd length set before cmd complete
  scsi: iscsi: Drop session lock in iscsi_session_chkready()
  scsi: qla4xxx: Use iscsi_is_session_online()
  scsi: libiscsi: Reset max/exp cmdsn during recovery
  scsi: iscsi_tcp: Fix shost can_queue initialization
  scsi: libiscsi: Add helper to calculate max SCSI cmds per session
  scsi: libiscsi: Fix iSCSI host workq destruction
  scsi: libiscsi: Fix iscsi_task use after free()
  scsi: libiscsi: Drop taskqueuelock
  scsi: libiscsi: Fix iscsi_prep_scsi_cmd_pdu() error handling
  ...