litmus-rt.git/drivers/infiniband/ulp/srp, branch linux-tip

SCSI host lock push-down

2010-11-16T21:33:23+00:00

Move the mid-layer's ->queuecommand() invocation from being locked
with the host lock to being unlocked to facilitate speeding up the
critical path for drivers who don't need this lock taken anyway.

The patch below presents a simple SCSI host lock push-down as an
equivalent transformation.  No locking or other behavior should change
with this patch.  All existing bugs and locking orders are preserved.

Additionally, add one parameter to queuecommand,
	struct Scsi_Host *
and remove one parameter from queuecommand,
	void (*done)(struct scsi_cmnd *)

Scsi_Host* is a convenient pointer that most host drivers need anyway,
and 'done' is redundant to struct scsi_cmnd->scsi_done.

Minimal code disturbance was attempted with this change.  Most drivers
needed only two one-line modifications for their host lock push-down.

Signed-off-by: Jeff Garzik 
Acked-by: James Bottomley 
Signed-off-by: Linus Torvalds

IB/srp: Sync buffer before posting send

2010-10-25T05:14:23+00:00

srp_send_tsk_mgmt() was missing the proper DMA sync calls before posting
the buffer to the device.

Signed-off-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Use list_first_entry()

2010-10-25T05:14:19+00:00

Use the list_first_entry() macro in ib_srp instead of open-coding the equivalent,
which makes the source code slightly more descriptive.  The list_first_entry()
macro itself was introduced in kernel 2.6.22.

Signed-off-by: Bart Van Assche 
Signed-off-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Reduce number of BUSY conditions

2010-10-25T05:14:14+00:00

As proposed by the SRP (draft) standard, ib_srp reserves one ring
element for SRP_TSK_MGMT requests. This patch makes sure that the SCSI
mid-layer never tries to queue more than (SRP request limit) - 1 SCSI
commands to ib_srp. This improves performance for targets whose request
limit is less than or equal to SRP_NORMAL_REQ_SQ_SIZE by reducing the
number of BUSY responses reported by ib_srp to the SCSI mid-layer.

Signed-off-by: Bart Van Assche 
Signed-off-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Eliminate two forward declarations

2010-10-25T05:14:08+00:00

Signed-off-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Implement SRP_CRED_REQ and SRP_AER_REQ

2010-10-23T05:19:10+00:00

This patch adds support for SRP_CRED_REQ to avoid a lockup by targets
that use that mechanism to return credits to the initiator. This
prevents a lockup observed in the field where we would never add the
credits from the SRP_CRED_REQ to our current count, and would therefore
never send another command to the target.

Minimal support for SRP_AER_REQ is also added, as these messages can
also be used to convey additional credits to the initiator.

Based upon extensive debugging and code by Bart Van Assche and a bug
report by Chris Worley.

Signed-off-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Preparation for transmit ring response allocation

2010-10-23T05:19:10+00:00

The transmit ring in ib_srp (srp_target.tx_ring) is currently only used
for allocating requests sent by the initiator to the target. This patch
prepares using that ring for allocation of both requests and responses.
Also, this patch differentiates the uses of SRP_SQ_SIZE, increases the
size of the IB send completion queue by one element and reserves one
transmit ring slot for SRP_TSK_MGMT requests.

Signed-off-by: Bart Van Assche 
Signed-off-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Export req_lim via sysfs

2010-08-04T20:02:26+00:00

Export req_lim via sysfs for debugging.

Signed-off-by: Bart Van Assche 
Acked-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Make receive buffer handling more robust

2010-08-04T18:47:39+00:00

The current strategy in ib_srp for posting receive buffers is:

 * Post one buffer after channel establishment.
 * Post one buffer before sending an SRP_CMD or SRP_TSK_MGMT to the target.

As a result, only the first non-SRP_RSP information unit from the
target will be processed.  If that first information unit is an
SRP_T_LOGOUT, it will be processed.  On the other hand, if the
initiator receives an SRP_CRED_REQ or SRP_AER_REQ before it receives a
SRP_T_LOGOUT, the SRP_T_LOGOUT won't be processed.

We can fix this inconsistency by changing the strategy for posting
receive buffers to:

 * Post all receive buffers after channel establishment.
 * After a receive buffer has been consumed and processed, post it again.

A side effect is that the ib_post_recv() call is moved out of the SCSI
command processing path.  Since __srp_post_recv() is not called
directly any more, get rid of it and move the code directly into
srp_post_recv().  Also, move srp_post_recv() up in the file to avoid a
forward declaration.

Signed-off-by: Bart Van Assche 
Acked-by: David Dillow 
Signed-off-by: Roland Dreier

IB/srp: Use print_hex_dump()

2010-08-04T18:24:12+00:00

Replace an open-coded dump of the receive buffer with a call to
print_hex_dump().

Signed-off-by: Bart Van Assche 
Signed-off-by: Roland Dreier