RDMA/srp: Make the channel count configurable per target

Increase the flexibility of the SRP initiator driver by making the channel
count configurable per target instead of only providing a kernel module
parameter for configuring the channel count.

Link: https://lore.kernel.org/r/20200525172212.14413-2-bvanassche@acm.orgSigned-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -3424,6 +3424,7 @@ enum {
 	SRP_OPT_IP_DEST		= 1 << 16,
 	SRP_OPT_TARGET_CAN_QUEUE= 1 << 17,
 	SRP_OPT_MAX_IT_IU_SIZE  = 1 << 18,
+	SRP_OPT_CH_COUNT	= 1 << 19,
 };
 
 static unsigned int srp_opt_mandatory[] = {
@@ -3457,6 +3458,7 @@ static const match_table_t srp_opt_tokens = {
 	{ SRP_OPT_IP_SRC,		"src=%s"		},
 	{ SRP_OPT_IP_DEST,		"dest=%s"		},
 	{ SRP_OPT_MAX_IT_IU_SIZE,	"max_it_iu_size=%d"	},
+	{ SRP_OPT_CH_COUNT,		"ch_count=%u",		},
 	{ SRP_OPT_ERR,			NULL 			}
 };
 
@@ -3758,6 +3760,14 @@ static int srp_parse_options(struct net *net, const char *buf,
 			target->max_it_iu_size = token;
 			break;
 
+		case SRP_OPT_CH_COUNT:
+			if (match_int(args, &token) || token < 1) {
+				pr_warn("bad channel count %s\n", p);
+				goto out;
+			}
+			target->ch_count = token;
+			break;
+
 		default:
 			pr_warn("unknown parameter or missing value '%s' in target creation request\n",
 				p);
@@ -3921,11 +3931,13 @@ static ssize_t srp_create_target(struct device *dev,
 		goto out;
 
 	ret = -ENOMEM;
-	target->ch_count = max_t(unsigned, num_online_nodes(),
-				 min(ch_count ? :
-				     min(4 * num_online_nodes(),
-					 ibdev->num_comp_vectors),
-				     num_online_cpus()));
+	if (target->ch_count == 0)
+		target->ch_count =
+			max_t(unsigned int, num_online_nodes(),
+			      min(ch_count ?:
+					  min(4 * num_online_nodes(),
+					      ibdev->num_comp_vectors),
+				  num_online_cpus()));
 	target->ch = kcalloc(target->ch_count, sizeof(*target->ch),
 			     GFP_KERNEL);
 	if (!target->ch)