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IB/srp: reduce lock coverage of command completion

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We only need the lock to cover list and credit manipulations, so push
those into srp_remove_req() and update the call chains.

We reorder the request removal and command completion in
srp_process_rsp() to avoid the SCSI mid-layer sending another command
before we've released our request and added any credits returned by the
target. This prevents us from returning HOST_BUSY unneccesarily.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ broken out, small cleanups, and modified to avoid potential extraneous
  HOST_BUSY returns by David Dillow ]
Signed-off-by: David Dillow <dillowda@ornl.gov>
This commit is contained in:
Bart Van Assche 2010-11-26 14:50:09 -05:00 committed by David Dillow
parent 76c75b258f
commit 94a9174c63
1 changed files with 14 additions and 23 deletions
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37
drivers/infiniband/ulp/srp/ib_srp.c
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@ -549,18 +549,24 @@ static void srp_unmap_data(struct scsi_cmnd *scmnd,
scsi_sg_count(scmnd), scmnd->sc_data_direction);
}
static void srp_remove_req(struct srp_target_port *target, struct srp_request *req)
static void srp_remove_req(struct srp_target_port *target,
struct srp_request *req, s32 req_lim_delta)
{
unsigned long flags;
srp_unmap_data(req->scmnd, target, req);
spin_lock_irqsave(target->scsi_host->host_lock, flags);
target->req_lim += req_lim_delta;
req->scmnd = NULL;
list_add_tail(&req->list, &target->free_reqs);
spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
}
static void srp_reset_req(struct srp_target_port *target, struct srp_request *req)
{
req->scmnd->result = DID_RESET << 16;
req->scmnd->scsi_done(req->scmnd);
srp_remove_req(target, req);
srp_remove_req(target, req, 0);
}
static int srp_reconnect_target(struct srp_target_port *target)
@ -595,13 +601,11 @@ static int srp_reconnect_target(struct srp_target_port *target)
while (ib_poll_cq(target->send_cq, 1, &wc) > 0)
; /* nothing */
spin_lock_irq(target->scsi_host->host_lock);
for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
struct srp_request *req = &target->req_ring[i];
if (req->scmnd)
srp_reset_req(target, req);
}
spin_unlock_irq(target->scsi_host->host_lock);
INIT_LIST_HEAD(&target->free_tx);
for (i = 0; i < SRP_SQ_SIZE; ++i)
@ -914,15 +918,12 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
struct srp_request *req;
struct scsi_cmnd *scmnd;
unsigned long flags;
s32 delta;
delta = (s32) be32_to_cpu(rsp->req_lim_delta);
spin_lock_irqsave(target->scsi_host->host_lock, flags);
target->req_lim += delta;
if (unlikely(rsp->tag & SRP_TAG_TSK_MGMT)) {
spin_lock_irqsave(target->scsi_host->host_lock, flags);
target->req_lim += be32_to_cpu(rsp->req_lim_delta);
spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
target->tsk_mgmt_status = -1;
if (be32_to_cpu(rsp->resp_data_len) >= 4)
target->tsk_mgmt_status = rsp->data[3];
@ -948,12 +949,10 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
else if (rsp->flags & (SRP_RSP_FLAG_DIOVER | SRP_RSP_FLAG_DIUNDER))
scsi_set_resid(scmnd, be32_to_cpu(rsp->data_in_res_cnt));
srp_remove_req(target, req, be32_to_cpu(rsp->req_lim_delta));
scmnd->host_scribble = NULL;
scmnd->scsi_done(scmnd);
srp_remove_req(target, req);
}
spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
}
static int srp_response_common(struct srp_target_port *target, s32 req_delta,
@ -1498,18 +1497,14 @@ static int srp_abort(struct scsi_cmnd *scmnd)
SRP_TSK_ABORT_TASK))
return FAILED;
spin_lock_irq(target->scsi_host->host_lock);
if (req->scmnd) {
if (!target->tsk_mgmt_status) {
srp_remove_req(target, req);
srp_remove_req(target, req, 0);
scmnd->result = DID_ABORT << 16;
} else
ret = FAILED;
}
spin_unlock_irq(target->scsi_host->host_lock);
return ret;
}
@ -1528,16 +1523,12 @@ static int srp_reset_device(struct scsi_cmnd *scmnd)
if (target->tsk_mgmt_status)
return FAILED;
spin_lock_irq(target->scsi_host->host_lock);
for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
struct srp_request *req = &target->req_ring[i];
if (req->scmnd && req->scmnd->device == scmnd->device)
srp_reset_req(target, req);
}
spin_unlock_irq(target->scsi_host->host_lock);
return SUCCESS;
}