We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

There's a rather long standing regression from the commit "libiscsi:
Reduce locking contention in fast path"

Depending on iSCSI target behavior, it's possible to hit the case in
iscsi_complete_task where the task is still on a pending list
(!list_empty(&task->running)).  When that happens the task is removed
from the list while holding the session back_lock, but other task list
modification occur under the frwd_lock.  That leads to linked list
corruption and eventually a panicked system.

Rather than back out the session lock split entirely, in order to try
and keep some of the performance gains this patch adds another lock to
maintain the task lists integrity.

Major enterprise supported kernels have been backing out the lock split
for while now, thanks to the efforts at IBM where a lab setup has the
most reliable reproducer I've seen on this issue.  This patch has been
tested there successfully.

Signed-off-by: Chris Leech <cleech@redhat.com>
Fixes: 659743b02c41 ("[SCSI] libiscsi: Reduce locking contention in fast path")
Reported-by: Prashantha Subbarao <psubbara@us.ibm.com>
Reviewed-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Instead define the timeout behavior purely based on the host_template
eh_timed_out method and wire up the existing transport implementations
in the host templates.  This also clears up the confusion that the
transport template method overrides the host template one, so some
drivers have to re-override the transport template one.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The code at free_task label in __iscsi_conn_send_pdu can get executed
from blk_timeout_work which takes queue_lock using spin_lock_irq.
back_lock taken with spin_unlock_bh will cause WARN_ON_ONCE.  The code
gets executed either with bottom half or IRQ disabled hence using
spin_lock/spin_unlock for back_lock is safe.

Signed-off-by: Jitendra Bhivare <jitendra.bhivare@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Chris Leech <cleech@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Avoid that building with W=1 causes gcc to report warnings about
set-but-not-used variables.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Running "git grep -nHw iscsi_eh_target_reset" shows that this function
is only called from inside the drivers/scsi/libiscsi.c source
file. Hence unexport this function.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Connection last_ping is not being updated when iscsi_send_nopout fails.
Not updating the last_ping will cause firing a timer to a past time
(last_ping + ping_tmo < current_time) which triggers an infinite loop of
iscsi_check_transport_timeouts() and hogs the cpu.

Fix this issue by checking the return value of iscsi_send_nopout.
If it fails set the next_timeout to one second later.

Signed-off-by: Ariel Nahum <arieln@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

Pull SCSI target updates from Nicholas Bellinger:
 "Here are the outstanding target-pending updates for v4.3-rc1.

  Mostly bug-fixes and minor changes this round.  The fallout from the
  big v4.2-rc1 RCU conversion have (thus far) been minimal.

  The highlights this round include:

   - Move sense handling routines into scsi_common code (Sagi)

   - Return ABORTED_COMMAND sense key for PI errors (Sagi)

   - Add tpg_enabled_sendtargets attribute for disabled iscsi-target
     discovery (David)

   - Shrink target struct se_cmd by rearranging fields (Roland)

   - Drop iSCSI use of mutex around max_cmd_sn increment (Roland)

   - Replace iSCSI __kernel_sockaddr_storage with sockaddr_storage (Andy +
     Chris)

   - Honor fabric max_data_sg_nents I/O transfer limit (Arun + Himanshu +
     nab)

   - Fix EXTENDED_COPY >= v4.1 regression OOPsen (Alex + nab)"

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (37 commits)
  target: use stringify.h instead of own definition
  target/user: Fix UFLAG_UNKNOWN_OP handling
  target: Remove no-op conditional
  target/user: Remove unused variable
  target: Fix max_cmd_sn increment w/o cmdsn mutex regressions
  target: Attach EXTENDED_COPY local I/O descriptors to xcopy_pt_sess
  target/qla2xxx: Honor max_data_sg_nents I/O transfer limit
  target/iscsi: Replace __kernel_sockaddr_storage with sockaddr_storage
  target/iscsi: Replace conn->login_ip with login_sockaddr
  target/iscsi: Keep local_ip as the actual sockaddr
  target/iscsi: Fix np_ip bracket issue by removing np_ip
  target: Drop iSCSI use of mutex around max_cmd_sn increment
  qla2xxx: Update tcm_qla2xxx module description to 24xx+
  iscsi-target: Add tpg_enabled_sendtargets for disabled discovery
  drivers: target: Drop unlikely before IS_ERR(_OR_NULL)
  target: check DPO/FUA usage for COMPARE AND WRITE
  target: Shrink struct se_cmd by rearranging fields
  target: Remove cmd->se_ordered_id (unused except debug log lines)
  target: add support for START_STOP_UNIT SCSI opcode
  target: improve unsupported opcode message
  ...

In case of hw iscsi offload, an host can have N-number of active
connections. There can be IO's running on some connections which
make host->host_busy always TRUE. Now if logout from a connection
is tried then the code gets into an infinite loop as host->host_busy
is always TRUE.

 iscsi_conn_teardown(....)
 {
   .........
    /*
     * Block until all in-progress commands for this connection
     * time out or fail.
     */
     for (;;) {
      spin_lock_irqsave(session->host->host_lock, flags);
      if (!atomic_read(&session->host->host_busy)) { /* OK for ERL == 0 */
	      spin_unlock_irqrestore(session->host->host_lock, flags);
              break;
      }
     spin_unlock_irqrestore(session->host->host_lock, flags);
     msleep_interruptible(500);
     iscsi_conn_printk(KERN_INFO, conn, "iscsi conn_destroy(): "
                 "host_busy %d host_failed %d\n",
	          atomic_read(&session->host->host_busy),
	          session->host->host_failed);

	................
	...............
     }
  }

This is not an issue with software-iscsi/iser as each cxn is a separate
host.

Fix:
Acquiring eh_mutex in iscsi_conn_teardown() before setting
session->state = ISCSI_STATE_TERMINATE.

Signed-off-by: John Soni Jose <sony.john@avagotech.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Chris Leech <cleech@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Odin.com>