netdev - [PATCH net-next] net: make SO_BUSY

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Date:   Thu,  6 Apr 2023 19:46:34 +0000
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] net: make SO_BUSY_POLL available to all users

After commit 217f69743681 ("net: busy-poll: allow preemption
in sk_busy_loop()"), a thread willing to use busy polling
is not hurting other threads anymore in a non preempt kernel.

I think it is safe to remove CAP_NET_ADMIN check.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/sock.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index c258887953905c340ad6deab8b66cbf45ecbf178..5440e67bcfe3b0874756fd87a9d79ded41c2e4a4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1396,15 +1396,10 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 
 #ifdef CONFIG_NET_RX_BUSY_POLL
 	case SO_BUSY_POLL:
-		/* allow unprivileged users to decrease the value */
-		if ((val > sk->sk_ll_usec) && !sockopt_capable(CAP_NET_ADMIN))
-			ret = -EPERM;
-		else {
-			if (val < 0)
-				ret = -EINVAL;
-			else
-				WRITE_ONCE(sk->sk_ll_usec, val);
-		}
+		if (val < 0)
+			ret = -EINVAL;
+		else
+			WRITE_ONCE(sk->sk_ll_usec, val);
 		break;
 	case SO_PREFER_BUSY_POLL:
 		if (valbool && !sockopt_capable(CAP_NET_ADMIN))
-- 
2.40.0.577.gac1e443424-goog