IB/sa: Fix sa_local_svc_timeout_ms read race

JIRA: https://issues.redhat.com/browse/RHEL-109942

commit 1428cd7
Author: Vlad Dumitrescu <vdumitrescu@nvidia.com>
Date:   Tue Sep 16 19:31:12 2025 +0300

    IB/sa: Fix sa_local_svc_timeout_ms read race

    When computing the delta, the sa_local_svc_timeout_ms is read without
    ib_nl_request_lock held. Though unlikely in practice, this can cause
    a race condition if multiple local service threads are managing the
    timeout.

    Fixes: 2ca546b ("IB/sa: Route SA pathrecord query through netlink")
    Signed-off-by: Vlad Dumitrescu <vdumitrescu@nvidia.com>
    Reviewed-by: Mark Zhang <markzhang@nvidia.com>
    Signed-off-by: Edward Srouji <edwards@nvidia.com>
    Link: https://patch.msgid.link/20250916163112.98414-1-edwards@nvidia.com
    Signed-off-by: Leon Romanovsky <leon@kernel.org>

Signed-off-by: Kamal Heib <kheib@redhat.com>

Author: Kamalheib

drivers/infiniband/core/sa_query.c

@@ -1013,14 +1013,15 @@ int ib_nl_handle_set_timeout(struct sk_buff *skb,
 	if (timeout > IB_SA_LOCAL_SVC_TIMEOUT_MAX)
 		timeout = IB_SA_LOCAL_SVC_TIMEOUT_MAX;
 
+	spin_lock_irqsave(&ib_nl_request_lock, flags);
+
 	delta = timeout - sa_local_svc_timeout_ms;
 	if (delta < 0)
 		abs_delta = -delta;
 	else
 		abs_delta = delta;
 
 	if (delta != 0) {
-		spin_lock_irqsave(&ib_nl_request_lock, flags);
 		sa_local_svc_timeout_ms = timeout;
 		list_for_each_entry(query, &ib_nl_request_list, list) {
 			if (delta < 0 && abs_delta > query->timeout)
@@ -1038,9 +1039,10 @@ int ib_nl_handle_set_timeout(struct sk_buff *skb,
 		if (delay)
 			mod_delayed_work(ib_nl_wq, &ib_nl_timed_work,
 					 (unsigned long)delay);
-		spin_unlock_irqrestore(&ib_nl_request_lock, flags);
 	}
 
+	spin_unlock_irqrestore(&ib_nl_request_lock, flags);
+
 settimeout_out:
 	return 0;
 }