Revert "ib_srpt: Convert to percpu_ida tag allocation"

This reverts commit 0fd10721fe3664f7549e74af9d28a509c9a68719.

That patch causes the ib_srpt driver to crash as soon as the first SCSI
command is received:

  kernel BUG at drivers/infiniband/ulp/srpt/ib_srpt.c:1439!
  invalid opcode: 0000 [#1] SMP
  Workqueue: target_completion target_complete_ok_work [target_core_mod]
  RIP: srpt_queue_response+0x437/0x4a0 [ib_srpt]
  Call Trace:
    srpt_queue_data_in+0x9/0x10 [ib_srpt]
    target_complete_ok_work+0x152/0x2b0 [target_core_mod]
    process_one_work+0x197/0x480
    worker_thread+0x49/0x490
    kthread+0xea/0x100
    ret_from_fork+0x22/0x40

Aside from the crash, the shortcomings of that patch are as follows:

 - It makes the ib_srpt driver use I/O contexts allocated by
   transport_alloc_session_tags() but it does not initialize these I/O
   contexts properly.  All the initializations performed by
   srpt_alloc_ioctx() are skipped.

 - It swaps the order of the send ioctx allocation and the transition to
   RTR mode which is wrong.

 - The amount of memory that is needed for I/O contexts is doubled.

 - srpt_rdma_ch.free_list is no longer used but is not removed.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.h b/drivers/infiniband/ulp/srpt/ib_srpt.h
index ca288f019315..af9b8b527340 100644
--- a/drivers/infiniband/ulp/srpt/ib_srpt.h
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.h
@@ -179,6 +179,7 @@ struct srpt_recv_ioctx {
  * struct srpt_send_ioctx - SRPT send I/O context.
  * @ioctx:       See above.
  * @ch:          Channel pointer.
+ * @free_list:   Node in srpt_rdma_ch.free_list.
  * @n_rbuf:      Number of data buffers in the received SRP command.
  * @rbufs:       Pointer to SRP data buffer array.
  * @single_rbuf: SRP data buffer if the command has only a single buffer.
@@ -201,6 +202,7 @@ struct srpt_send_ioctx {
 	struct srp_direct_buf	*rbufs;
 	struct srp_direct_buf	single_rbuf;
 	struct scatterlist	*sg;
+	struct list_head	free_list;
 	spinlock_t		spinlock;
 	enum srpt_command_state	state;
 	struct se_cmd		cmd;