mptcp: remove unneeded lock when listing scheds

mptcp_get_available_schedulers() needs to iterate over the schedulers'
list only to read the names: it doesn't modify anything there.

In this case, it is enough to hold the RCU read lock, no need to combine
this with the associated spin lock as it was done since its introduction
in commit 73c900aa3660 ("mptcp: add net.mptcp.available_schedulers").

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Geliang Tang <geliang@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241104-net-next-mptcp-sched-unneeded-lock-v2-1-2ccc1e0c750c@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index 78ed508ebc1b8dd9f0e020cca1bdd86f24f0afeb..df7dbcfa3b71370cc4d7e4e4f16cc1e41a50dddf 100644 (file)
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -60,7 +60,6 @@ void mptcp_get_available_schedulers(char *buf, size_t maxlen)
        size_t offs = 0;
 
        rcu_read_lock();
-       spin_lock(&mptcp_sched_list_lock);
        list_for_each_entry_rcu(sched, &mptcp_sched_list, list) {
                offs += snprintf(buf + offs, maxlen - offs,
                                 "%s%s",
@@ -69,7 +68,6 @@ void mptcp_get_available_schedulers(char *buf, size_t maxlen)
                if (WARN_ON_ONCE(offs >= maxlen))
                        break;
        }
-       spin_unlock(&mptcp_sched_list_lock);
        rcu_read_unlock();
 }