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IB/srp: Make receive buffer handling more robust

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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 <bart.vanassche@gmail.com>
Acked-by: David Dillow <dave@thedillows.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Bart Van Assche 2010-07-30 10:59:05 +00:00 committed by Roland Dreier
parent 7a7008110b
commit c996bb47bb
1 changed files with 44 additions and 45 deletions
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89
drivers/infiniband/ulp/srp/ib_srp.c
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@ -811,6 +811,38 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
return len;
}
static int srp_post_recv(struct srp_target_port *target)
{
unsigned long flags;
struct srp_iu *iu;
struct ib_sge list;
struct ib_recv_wr wr, *bad_wr;
unsigned int next;
int ret;
spin_lock_irqsave(target->scsi_host->host_lock, flags);
next = target->rx_head & (SRP_RQ_SIZE - 1);
wr.wr_id = next;
iu = target->rx_ring[next];
list.addr = iu->dma;
list.length = iu->size;
list.lkey = target->srp_host->srp_dev->mr->lkey;
wr.next = NULL;
wr.sg_list = &list;
wr.num_sge = 1;
ret = ib_post_recv(target->qp, &wr, &bad_wr);
if (!ret)
++target->rx_head;
spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
return ret;
}
static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
{
struct srp_request *req;
@ -868,6 +900,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
{
struct ib_device *dev;
struct srp_iu *iu;
int res;
u8 opcode;
iu = target->rx_ring[wc->wr_id];
@ -904,6 +937,11 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
ib_dma_sync_single_for_device(dev, iu->dma, target->max_ti_iu_len,
DMA_FROM_DEVICE);
res = srp_post_recv(target);
if (res != 0)
shost_printk(KERN_ERR, target->scsi_host,
PFX "Recv failed with error code %d\n", res);
}
static void srp_recv_completion(struct ib_cq *cq, void *target_ptr)
@ -943,45 +981,6 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
}
}
static int __srp_post_recv(struct srp_target_port *target)
{
struct srp_iu *iu;
struct ib_sge list;
struct ib_recv_wr wr, *bad_wr;
unsigned int next;
int ret;
next = target->rx_head & (SRP_RQ_SIZE - 1);
wr.wr_id = next;
iu = target->rx_ring[next];
list.addr = iu->dma;
list.length = iu->size;
list.lkey = target->srp_host->srp_dev->mr->lkey;
wr.next = NULL;
wr.sg_list = &list;
wr.num_sge = 1;
ret = ib_post_recv(target->qp, &wr, &bad_wr);
if (!ret)
++target->rx_head;
return ret;
}
static int srp_post_recv(struct srp_target_port *target)
{
unsigned long flags;
int ret;
spin_lock_irqsave(target->scsi_host->host_lock, flags);
ret = __srp_post_recv(target);
spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
return ret;
}
/*
* Must be called with target->scsi_host->host_lock held to protect
* req_lim and tx_head. Lock cannot be dropped between call here and
@ -1091,11 +1090,6 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
goto err;
}
if (__srp_post_recv(target)) {
shost_printk(KERN_ERR, target->scsi_host, PFX "Recv failed\n");
goto err_unmap;
}
ib_dma_sync_single_for_device(dev, iu->dma, srp_max_iu_len,
DMA_TO_DEVICE);
@ -1238,6 +1232,7 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
int attr_mask = 0;
int comp = 0;
int opcode = 0;
int i;
switch (event->event) {
case IB_CM_REQ_ERROR:
@ -1287,7 +1282,11 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
if (target->status)
break;
target->status = srp_post_recv(target);
for (i = 0; i < SRP_RQ_SIZE; i++) {
target->status = srp_post_recv(target);
if (target->status)
break;
}
if (target->status)
break;