cppcheck found the following issue:
(warning) Logical conjunction always evaluates to false:
  alloc_len < 4 && alloc_len > 65535.

..the test should be instead:

  if (alloc_len < 4 || alloc_len > 65536)

This error was introduced by recent commit 38d5c8336e60bf6e53a1da9
("scsi_debug: add Report supported opcodes+tmfs; Compare and write")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

resp_rsup_opcodes() may get called from atomic context and would need to
use GFP_ATOMIC for allocations:

[ 1237.913419] BUG: sleeping function called from invalid context at mm/slub.c:1262
[ 1237.914865] in_atomic(): 1, irqs_disabled(): 0, pid: 7556, name: trinity-c311
[ 1237.916142] 3 locks held by trinity-c311/7556:
[ 1237.916981] #0: (sb_writers#5){.+.+.+}, at: do_readv_writev (include/linux/fs.h:2346 fs/read_write.c:844)
[ 1237.919713] #1: (&of->mutex){+.+.+.}, at: kernfs_fop_write (fs/kernfs/file.c:297)
[ 1237.922626] Mutex: counter: -1 owner: trinity-c311
[ 1237.924044] #2: (s_active#51){.+.+.+}, at: kernfs_fop_write (fs/kernfs/file.c:297)
[ 1237.925960] Preemption disabled blk_execute_rq_nowait (block/blk-exec.c:95)
[ 1237.927416]
[ 1237.927680] CPU: 24 PID: 7556 Comm: trinity-c311 Not tainted 3.19.0-rc4-next-20150116-sasha-00054-g4ad498c-dirty #1744
[ 1237.929603]  ffff8804fc9d8000 ffff8804d9bc3548 ffffffff9d439fb2 0000000000000000
[ 1237.931097]  0000000000000000 ffff8804d9bc3588 ffffffff9a18389a ffff8804d9bc3598
[ 1237.932466]  ffffffff9a1b1715 ffffffffa15935d8 ffffffff9e6f8cb1 00000000000004ee
[ 1237.933984] Call Trace:
[ 1237.934434] dump_stack (lib/dump_stack.c:52)
[ 1237.935323] ___might_sleep (kernel/sched/core.c:7339)
[ 1237.936259] ? mark_held_locks (kernel/locking/lockdep.c:2549)
[ 1237.937293] __might_sleep (kernel/sched/core.c:7305)
[ 1237.938272] __kmalloc (mm/slub.c:1262 mm/slub.c:2419 mm/slub.c:2491 mm/slub.c:3291)
[ 1237.939137] ? resp_rsup_opcodes (include/linux/slab.h:435 drivers/scsi/scsi_debug.c:1689)
[ 1237.940173] resp_rsup_opcodes (include/linux/slab.h:435 drivers/scsi/scsi_debug.c:1689)
[ 1237.941211] ? add_host_store (drivers/scsi/scsi_debug.c:1584)
[ 1237.942261] scsi_debug_queuecommand (drivers/scsi/scsi_debug.c:5276)
[ 1237.943404] ? blk_rq_map_sg (block/blk-merge.c:254)
[ 1237.944398] ? scsi_init_sgtable (drivers/scsi/scsi_lib.c:1095)
[ 1237.945402] sdebug_queuecommand_lock_or_not (drivers/scsi/scsi_debug.c:5300)
[ 1237.946735] scsi_dispatch_cmd (drivers/scsi/scsi_lib.c:1706)
[ 1237.947720] scsi_queue_rq (drivers/scsi/scsi_lib.c:1996)
[ 1237.948687] __blk_mq_run_hw_queue (block/blk-mq.c:816)
[ 1237.949796] blk_mq_run_hw_queue (block/blk-mq.c:896)
[ 1237.950903] ? _raw_spin_unlock (./arch/x86/include/asm/preempt.h:95 include/linux/spinlock_api_smp.h:154 kernel/locking/spinlock.c:183)
[ 1237.951862] blk_mq_insert_request (block/blk-mq.c:1037)
[ 1237.952876] blk_execute_rq_nowait (block/blk-exec.c:95)
[ 1237.953981] ? lockdep_init_map (kernel/locking/lockdep.c:3034)
[ 1237.954967] blk_execute_rq (block/blk-exec.c:131)
[ 1237.955929] ? blk_rq_bio_prep (block/blk-core.c:2835)
[ 1237.956913] scsi_execute (drivers/scsi/scsi_lib.c:252)
[ 1237.957821] scsi_execute_req_flags (drivers/scsi/scsi_lib.c:281)
[ 1237.958968] scsi_report_opcode (drivers/scsi/scsi.c:956)
[ 1237.960009] sd_revalidate_disk (drivers/scsi/sd.c:2707 drivers/scsi/sd.c:2792)
[ 1237.961139] revalidate_disk (fs/block_dev.c:1081)
[ 1237.962223] sd_rescan (drivers/scsi/sd.c:1532)
[ 1237.963142] scsi_rescan_device (drivers/scsi/scsi_scan.c:1579)
[ 1237.964165] store_rescan_field (drivers/scsi/scsi_sysfs.c:672)
[ 1237.965254] dev_attr_store (drivers/base/core.c:138)
[ 1237.966319] sysfs_kf_write (fs/sysfs/file.c:131)
[ 1237.967289] kernfs_fop_write (fs/kernfs/file.c:311)
[ 1237.968274] do_readv_writev (fs/read_write.c:722 fs/read_write.c:854)
[ 1237.969295] ? __acct_update_integrals (kernel/tsacct.c:145)
[ 1237.970452] ? kernfs_fop_open (fs/kernfs/file.c:271)
[ 1237.971505] ? _raw_spin_unlock (./arch/x86/include/asm/preempt.h:95 include/linux/spinlock_api_smp.h:154 kernel/locking/spinlock.c:183)
[ 1237.972512] ? context_tracking_user_exit (include/linux/vtime.h:89 include/linux/jump_label.h:114 include/trace/events/context_tracking.h:47 kernel/context_tracking.c:140)
[ 1237.973668] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2578 kernel/locking/lockdep.c:2625)
[ 1237.974882] ? trace_hardirqs_on (kernel/locking/lockdep.c:2633)
[ 1237.975850] vfs_writev (fs/read_write.c:893)
[ 1237.976691] SyS_writev (fs/read_write.c:926 fs/read_write.c:917)
[ 1237.977538] system_call_fastpath (arch/x86/kernel/entry_64.S:423)

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

This eliminates a superfluous log message when the capacity is changed:

  "check_readiness: unexpected unit attention code=3"

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

All other traversals of the sdebug_host_list take the lock.

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Kernel build tools pointed out a memory leak so that has been
fixed and its error paths strengthened with a goto. Testing
showed compare and write was only working for lba=0; correcting
the length of the LBA field fixed that.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

For SPI drivers use the message definitions from scsi.h, and for target
drivers introduce a new TCM_*_TAG namespace.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com

Since we got rid of ordered tag support in 2010 the prime use case of
switching on and off ordered tags has been obsolete.  The other function
of enabling/disabling tagging entirely has only been correctly implemented
by the 53c700 driver and isn't generally useful.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com
Reviewed-by: Hannes Reinecke <hare@suse.de>

The Report supported operation codes command is very closely integrated
into the table driven parser and very useful for testing it. Its cdb
masks form the basis of the 'strict' parameter's checks. The Report
supported TMFs command is a simple extension. The Compare and write
command may even be useful, as it should be atomic due to the read-write
lock that the driver uses on its backing store (ram).

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

The existing 'big switch' parser in queuecommand() is changed to
a table driven parser. The old and new queuecommand() were moved
in the source so diff would not shuffle them. Apart from the new
tables most other changes are refactoring existing response code
to be more easily called out of the table parser. The 'strict'
parameter is added so that cdb_s can be checked for non-zero
values in parts of the cdb that are reserved. Some other changes
include: tweak request sense response when D_SENSE differs; support
NDOB in Write Same(16); and fix crash in Get LBA Status when LBP
was inactive.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Via sysfs the virtual_gb scsi_debug parameter can be changed while
LUs are in use. If that changes, the 'Capacity data has changed'
Unit Attention is queued on all LUs.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>