[PATCH net-next] net: print error if SO_BUSY_POLL_BUDGET is large

[Joe Damato <jdamato@fastly.com>]

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