Bart Van Assche wrote:
On 06/13/13 19:50, Vu Pham wrote:
Hello Bart,
+/**
+ * srp_conn_unique() - check whether the connection to a target is
unique
+ */
+static bool srp_conn_unique(struct srp_host *host,
+ struct srp_target_port *target)
+{
+ struct srp_target_port *t;
+ bool ret = false;
+
+ if (target->state == SRP_TARGET_REMOVED)
+ goto out;
+
+ ret = true;
+
+ spin_lock(&host->target_lock);
+ list_for_each_entry(t, &host->target_list, list) {
+ if (t != target &&
+ target->id_ext == t->id_ext &&
Targets may advertise/expose on different pkeys
You can have multiple connections (or paths/scsi hosts) to same target
with different pkeys.
We need extra check to detect the uniqueness:
target->path.pkey ==
t->path.pkey &&
Hello Vu,
Thanks for the feedback. This is something I have already thinking
about myself. Unfortunately I have not found any requirements in the
T10 SRP standard with regard to InfiniBand partitions. However, in
that document there is a section about single RDMA channel operation.
In that section it is explained that an SRP target must log out
established sessions upon receipt of a new login request. What I'm not
sure about is whether only sessions with the same P_Key must be logged
out or all established sessions if a new login request is received. I
assume the latter since otherwise that would mean that an SRP target
would be required to maintain multiple sessions if it allows
connections with more than one P_Key to a target port ? My concern
about adding a pkey comparison in the function srp_conn_unique() is
that if a target allows an initiator to choose which partition to use
when logging in, that this could result in the undesired SRP initiator
ping-pong effect this patch tries to avoid.
Bart.
Hello Bart,
Yes, you pointed out the unclear/undefined area.
If we stick to single RDMA channel per IT Nexus with unique tuple
Initiator Port Identier - Target Port Indentifier then newly created
connection with same tuple (I_port_id, T_port_id) but with different
P_Key or different DGID is not unique.
Sticking to this rule by excluding P_Key and DGID out of rdma channel
indentity, your srp_conn_unique() checking is ok; however, some SRP
target implementations may include DGID as part of rdma channel
identifier. I'm not sure about different p_key part.
-vu
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