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Date:   Wed, 25 Jul 2018 12:35:13 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Davidlohr Bueso <dave@stgolabs.net>
Cc:     jbaron@akamai.com, viro@zeniv.linux.org.uk,
        linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH -next] fs/epoll: simply CONFIG_NET_RX_BUSY_POLL ifdefery
Message-Id: <20180725123513.5f36a6b787d06c8066a24ade@linux-foundation.org>
In-Reply-To: <20180725185620.11020-1-dave@stgolabs.net>
References: <20180725185620.11020-1-dave@stgolabs.net>
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On Wed, 25 Jul 2018 11:56:20 -0700 Davidlohr Bueso <dave@stgolabs.net> wrote:

> ... 'tis easier on the eye.

true, but.

> +#else
> +#define ep_busy_loop(ep, nonblock)		do { } while (0)
> +#define ep_reset_busy_poll_napi_id(ep)		do { } while (0)
> +#define ep_set_busy_poll_napi_id(epi)		do { } while (0)
> +
> +#endif /* CONFIG_NET_RX_BUSY_POLL */

inlines are preferred.  Because macros are fugly and can cause
unused-var warnings when the stub versions are used.

This?

--- a/fs/eventpoll.c~fs-epoll-simply-config_net_rx_busy_poll-ifdefery-fix
+++ a/fs/eventpoll.c
@@ -449,9 +449,18 @@ static inline void ep_set_busy_poll_napi
 }
 
 #else
-#define ep_busy_loop(ep, nonblock)		do { } while (0)
-#define ep_reset_busy_poll_napi_id(ep)		do { } while (0)
-#define ep_set_busy_poll_napi_id(epi)		do { } while (0)
+
+static inline void ep_busy_loop(struct eventpoll *ep, int nonblock)
+{
+}
+
+static inline void ep_reset_busy_poll_napi_id(struct eventpoll *ep)
+{
+}
+
+static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
+{
+}
 
 #endif /* CONFIG_NET_RX_BUSY_POLL */
 
_