linux-toradex.git/drivers/target/target_core_device.c, branch v5.17

scsi: target: Fix ordered tag handling

2021-10-19T02:38:35+00:00

This patch fixes the following bugs:

1. If there are multiple ordered cmds queued and multiple simple cmds
   completing, target_restart_delayed_cmds() could be called on different
   CPUs and each instance could start a ordered cmd. They could then run in
   different orders than they were queued.

2. target_restart_delayed_cmds() and target_handle_task_attr() can race
   where:

   1. target_handle_task_attr() has passed the simple_cmds == 0 check.

   2. transport_complete_task_attr() then decrements simple_cmds to 0.

   3. transport_complete_task_attr() runs target_restart_delayed_cmds() and
      it does not see any cmds on the delayed_cmd_list.

   4. target_handle_task_attr() adds the cmd to the delayed_cmd_list.

   The cmd will then end up timing out.

3. If we are sent > 1 ordered cmds and simple_cmds == 0, we can execute
   them out of order, because target_handle_task_attr() will hit that
   simple_cmds check first and return false for all ordered cmds sent.

4. We run target_restart_delayed_cmds() after every cmd completion, so if
   there is more than 1 simple cmd running, we start executing ordered cmds
   after that first cmd instead of waiting for all of them to complete.

5. Ordered cmds are not supposed to start until HEAD OF QUEUE and all older
   cmds have completed, and not just simple.

6. It's not a bug but it doesn't make sense to take the delayed_cmd_lock
   for every cmd completion when ordered cmds are almost never used. Just
   replacing that lock with an atomic increases IOPs by up to 10% when
   completions are spread over multiple CPUs and there are multiple
   sessions/ mqs/thread accessing the same device.

This patch moves the queued delayed handling to a per device work to
serialze the cmd executions for each device and adds a new counter to track
HEAD_OF_QUEUE and SIMPLE cmds. We can then check the new counter to
determine when to run the work on the completion path.

Link: https://lore.kernel.org/r/20210930020422.92578-3-michael.christie@oracle.com
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: core: Add configurable IEEE Company ID attribute

2021-05-15T18:14:28+00:00

Implement an attribute which provides a way to set a company specific WWN
in configfs via:

  target/core/$backstore/$name/wwn/company_id

The Open Fabrics Alliance ID 001405h remains the default.

Link: https://lore.kernel.org/r/20210420185920.42431-3-s.samoylenko@yadro.com
Signed-off-by: Sergey Samoylenko 
Signed-off-by: Roman Bolshakov 
Signed-off-by: Martin K. Petersen

scsi: target: Make the virtual LUN 0 device

2021-04-06T03:26:39+00:00

Create the device for the virtual LUN 0 using the DUMMY flag. This change
makes it possible to remove some special-casing in the INQUIRY code.

Link: https://lore.kernel.org/r/20210322200938.53300-3-k.shelekhin@yadro.com
Reviewed-by: Roman Bolshakov 
Reviewed-by: Mike Christie 
Signed-off-by: Konstantin Shelekhin 
Signed-off-by: Martin K. Petersen

scsi: target: core: Add workqueue based cmd submission

2021-03-04T22:37:02+00:00

loop and vhost/scsi do their target cmd submission from driver
workqueues. This allows them to avoid an issue where the backend may block
waiting for resources like tags/requests, mem/locks, etc and that ends up
blocking their entire submission path and for the case of vhost-scsi both
the submission and completion path.

This patch adds a helper drivers can use to submit from a LIO workqueue.
This code will then be extended in the next patches to fix the plugging of
backend devices.

We are only converting vhost/loop initially, but the workqueue based
submission will work for other drivers and have similar benefits where the
main target loops will not end up blocking one some backend resource.

Link: https://lore.kernel.org/r/20210227170006.5077-17-michael.christie@oracle.com
Tested-by: Laurence Oberman 
Reviewed-by: Bodo Stroesser 
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: Make state_list per CPU

2020-11-05T03:39:38+00:00

Do a state_list/execute_task_lock per CPU, so we can do submissions from
different CPUs without contention with each other.

Note: tcm_fc was passing TARGET_SCF_USE_CPUID, but never set cpuid.  The
assumption is that it wanted to set the cpuid to the CPU it was submitting
from so it will get this behavior with this patch.

[mkp: s/printk/pr_err/ + resolve COMPARE AND WRITE patch conflict]

Link: https://lore.kernel.org/r/1604257174-4524-8-git-send-email-michael.christie@oracle.com
Reviewed-by: Himanshu Madhani 
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: Fix LUN ref count handling

2020-11-05T03:39:37+00:00

Fix two bugs in the LUN refcounting:

 1. For the TCM_WRITE_PROTECTED case we were returning an error after
    taking a ref to the LUN, but never dropping it (caller just send status
    and drops cmd ref).

 2. We still need to do a percpu_ref_tryget_live for the virt LUN 0 like we
    do for other LUNs, because the TPG code does the refcount/wait process
    like it does with other LUNs.

Link: https://lore.kernel.org/r/1604257174-4524-2-git-send-email-michael.christie@oracle.com
Reviewed-by: Himanshu Madhani 
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: Initialize LUN in transport_init_se_cmd()

2020-06-10T01:57:26+00:00

Initialization of orig_fe_lun is moved to transport_init_se_cmd() from
transport_lookup_cmd_lun(). This helps for the cases where the SCSI request
fails before the call to transport_lookup_cmd_lun() so that
trace_target_cmd_complete() can print the LUN information to the trace
buffer. Due to this change, the lun parameter is removed from
transport_lookup_cmd_lun() and transport_lookup_tmr_lun().

Link: https://lore.kernel.org/r/1591559913-8388-3-git-send-email-sudhakar.panneerselvam@oracle.com
Reviewed-by: Mike Christie 
Signed-off-by: Sudhakar Panneerselvam 
Signed-off-by: Martin K. Petersen

scsi: target: core: Add initiatorname to NON_EXISTENT_LUN error

2020-05-20T01:27:10+00:00

The NON_EXISTENT_LUN error can be written without an error condition
on the initiator responsible. Adding the initiatorname to this message
will reduce the effort required to fix this when many initiators are
supported by a target.

This version ensures the initiator name is also printed on the same message
in transport_lookup_tmr_lun for consistency.

Link: https://lore.kernel.org/r/9b13bb2e1f52f1792cd81850ee95bf3781bb5363.1589759816.git.lance.digby@gmail.com
Reviewed-by: Mike Christie 
Signed-off-by: Lance Digby 
Signed-off-by: Martin K. Petersen

scsi: target: Make transport_flags per device

2020-05-08T02:39:21+00:00

pgr_support and alua_support device attributes show the inverted value of
the transport_flags:

 * TRANSPORT_FLAG_PASSTHROUGH_PGR
 * TRANSPORT_FLAG_PASSTHROUGH_ALUA

These attributes are per device, while the flags are per backend. Rename
the transport_flags in backend/transport to transport_flags_default and use
this value to initialize the new transport_flags field in the se_device
structure.

Now data and attribute both are per se_device.

Link: https://lore.kernel.org/r/20200427150823.15350-4-bstroesser@ts.fujitsu.com
Reviewed-by: Mike Christie 
Signed-off-by: Bodo Stroesser 
Signed-off-by: Martin K. Petersen

scsi: target: use an enum to track emulate_ua_intlck_ctrl

2020-02-21T22:37:16+00:00

The emulate_ua_intlck_ctrl device attribute accepts values of 0, 1 or 2 via
ConfigFS, which map to unit attention interlocks control codes in the MODE
SENSE control Mode Page.  Use an enum to track these values so that it's
clear that, unlike the remaining emulate_X attributes,
emulate_ua_intlck_ctrl isn't boolean.

Link: https://marc.info/?l=target-devel&m=158227825428798
Suggested-by: Bart Van Assche 
Signed-off-by: David Disseldorp 
Signed-off-by: Martin K. Petersen