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From: Joe Damato <jdamato@fastly.com>
To: linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org
Cc: dhowells@redhat.com,
	alexander@mihalicyn.com,
	leitao@debian.org,
	wuyun.abel@bytedance.com,
	kuniyu@amazon.com,
	pabeni@redhat.com,
	kuba@kernel.org,
	edumazet@google.com,
	davem@davemloft.net,
	Joe Damato <jdamato@fastly.com>
Subject: [PATCH net-next] net: print error if SO_BUSY_POLL_BUDGET is large
Date: Thu, 25 Jan 2024 19:18:40 +0000
Message-Id: <20240125191840.6740-1-jdamato@fastly.com>
Precedence: bulk
MIME-Version: 1.0
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When drivers call netif_napi_add_weight with a weight that is larger
than NAPI_POLL_WEIGHT, the networking code allows the larger weight, but
prints an error.

Replicate this check for SO_BUSY_POLL_BUDGET; check if the user
specified amount exceeds NAPI_POLL_WEIGHT, allow it anyway, but print an
error.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 net/core/sock.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/sock.c b/net/core/sock.c
index 158dbdebce6a..ed243bd0dd77 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1153,6 +1153,9 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 			return -EPERM;
 		if (val < 0 || val > U16_MAX)
 			return -EINVAL;
+		if (val > NAPI_POLL_WEIGHT)
+			pr_err("SO_BUSY_POLL_BUDGET %u exceeds suggested maximum %u\n", val,
+			       NAPI_POLL_WEIGHT);
 		WRITE_ONCE(sk->sk_busy_poll_budget, val);
 		return 0;
 #endif
-- 
2.25.1