IB/srp: Allow sg_tablesize to be adjusted

Make the sg_tablesize used by SRP adjustable at module load time via a
module parameter.  Calculate the corresponding IU length required to
support this.

Signed-off-by: Vu Pham <vu@mellanox.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 17 insertions, 9 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 8e6b10369717..a01b73bb976e 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -62,6 +62,13 @@ MODULE_DESCRIPTION("InfiniBand SCSI RDMA Protocol initiator "
                    "v" DRV_VERSION " (" DRV_RELDATE ")");
 MODULE_LICENSE("Dual BSD/GPL");
 
+static int srp_sg_tablesize = SRP_DEF_SG_TABLESIZE;
+static int srp_max_iu_len;
+
+module_param(srp_sg_tablesize, int, 0444);
+MODULE_PARM_DESC(srp_sg_tablesize,
+                 "Max number of gather/scatter entries per I/O (default is 12)");
+
 static int topspin_workarounds = 1;
 
 module_param(topspin_workarounds, int, 0444);
@@ -311,7 +318,7 @@ static int srp_send_req(struct srp_target_port *target)
 
         req->priv.opcode        = SRP_LOGIN_REQ;
         req->priv.tag           = 0;
-        req->priv.req_it_iu_len = cpu_to_be32(SRP_MAX_IU_LEN);
+        req->priv.req_it_iu_len = cpu_to_be32(srp_max_iu_len);
         req->priv.req_buf_fmt   = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
                                               SRP_BUF_FORMAT_INDIRECT);
         memcpy(req->priv.initiator_port_id, target->srp_host->initiator_port_id, 16);
@@ -953,7 +960,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
                 goto err;
 
         dma_sync_single_for_cpu(target->srp_host->dev->dev->dma_device, iu->dma,
-                                SRP_MAX_IU_LEN, DMA_TO_DEVICE);
+                                srp_max_iu_len, DMA_TO_DEVICE);
 
         req = list_entry(target->free_reqs.next, struct srp_request, list);
 
@@ -986,7 +993,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
         }
 
         dma_sync_single_for_device(target->srp_host->dev->dev->dma_device, iu->dma,
-                                   SRP_MAX_IU_LEN, DMA_TO_DEVICE);
+                                   srp_max_iu_len, DMA_TO_DEVICE);
 
         if (__srp_post_send(target, iu, len)) {
                 printk(KERN_ERR PFX "Send failed\n");
@@ -1018,7 +1025,7 @@ static int srp_alloc_iu_bufs(struct srp_target_port *target)
 
         for (i = 0; i < SRP_SQ_SIZE + 1; ++i) {
                 target->tx_ring[i] = srp_alloc_iu(target->srp_host,
-                                                  SRP_MAX_IU_LEN,
+                                                  srp_max_iu_len,
                                                   GFP_KERNEL, DMA_TO_DEVICE);
                 if (!target->tx_ring[i])
                         goto err;
@@ -1436,7 +1443,6 @@ static struct scsi_host_template srp_template = {
         .eh_host_reset_handler          = srp_reset_host,
         .can_queue                      = SRP_SQ_SIZE,
         .this_id                        = -1,
-        .sg_tablesize                   = SRP_MAX_INDIRECT,
         .cmd_per_lun                    = SRP_SQ_SIZE,
         .use_clustering                 = ENABLE_CLUSTERING,
         .shost_attrs                    = srp_host_attrs
@@ -1914,6 +1920,11 @@ static int __init srp_init_module(void)
 {
         int ret;
 
+        srp_template.sg_tablesize = srp_sg_tablesize;
+        srp_max_iu_len = (sizeof (struct srp_cmd) +
+                          sizeof (struct srp_indirect_buf) +
+                          srp_sg_tablesize * 16);
+
         ret = class_register(&srp_class);
         if (ret) {
                 printk(KERN_ERR PFX "couldn't register class infiniband_srp\n");
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index c071c3032700..033a44772ae3 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -56,7 +56,7 @@ enum {
         SRP_DLID_REDIRECT       = 2,
 
         SRP_MAX_LUN             = 512,
-        SRP_MAX_IU_LEN          = 256,
+        SRP_DEF_SG_TABLESIZE    = 12,
 
         SRP_RQ_SHIFT            = 6,
         SRP_RQ_SIZE             = 1 << SRP_RQ_SHIFT,
@@ -71,9 +71,6 @@ enum {
 };
 
 #define SRP_OP_RECV             (1 << 31)
-#define SRP_MAX_INDIRECT        ((SRP_MAX_IU_LEN -                      \
-                                  sizeof (struct srp_cmd) -             \
-                                  sizeof (struct srp_indirect_buf)) / 16)
 
 enum srp_target_state {
         SRP_TARGET_LIVE,