Re: [PATCH -next v2] sunrpc: Use no_printk() in dfprintk*() dummies

Jeff Layton
2023-10-12T10:13:39Z

On Thu, 2023-10-12 at 12:08 +0200, Geert Uytterhoeven wrote:
> When building NFS with W=1 and CONFIG_WERROR=y, but
> CONFIG_SUNRPC_DEBUG=n:
>
> fs/nfs/nfs4proc.c: In function ‘nfs4_proc_create_session’:
> fs/nfs/nfs4proc.c:9276:19: error: variable ‘ptr’ set but not used [-Werror=unused-but-set-variable]
> 9276 | unsigned *ptr;
> | ^~~
> CC fs/nfs/callback.o
> fs/nfs/callback.c: In function ‘nfs41_callback_svc’:
> fs/nfs/callback.c:98:13: error: variable ‘error’ set but not used [-Werror=unused-but-set-variable]
> 98 | int error;
> | ^~~~~
> CC fs/nfs/flexfilelayout/flexfilelayout.o
> fs/nfs/flexfilelayout/flexfilelayout.c: In function ‘ff_layout_io_track_ds_error’:
> fs/nfs/flexfilelayout/flexfilelayout.c:1230:13: error: variable ‘err’ set but not used [-Werror=unused-but-set-variable]
> 1230 | int err;
> | ^~~
> CC fs/nfs/flexfilelayout/flexfilelayoutdev.o
> fs/nfs/flexfilelayout/flexfilelayoutdev.c: In function ‘nfs4_ff_alloc_deviceid_node’:
> fs/nfs/flexfilelayout/flexfilelayoutdev.c:55:16: error: variable ‘ret’ set but not used [-Werror=unused-but-set-variable]
> 55 | int i, ret = -ENOMEM;
> | ^~~
>
> All these are due to variables that are set unconditionally, but are
> used only when debugging is enabled.
>
> Fix this by changing the dfprintk*() dummy macros from empty loops to
> calls to the no_printk() helper. This informs the compiler that the
> passed debug parameters are actually used, and enables format specifier
> checking as a bonus.
>
> This requires removing the protection by CONFIG_SUNRPC_DEBUG of the
> declaration of nlmdbg_cookie2a(), as its reference is now visible to the
> compiler, but optimized away.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> v2:
> - s/uncontionally/unconditionally/,
> - Drop CONFIG_SUNRPC_DEBUG check in fs/lockd/svclock.c to fix build
> failure.
> ---
> fs/lockd/svclock.c | 2 --
> include/linux/sunrpc/debug.h | 6 +++---
> 2 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index 43aeba9de55cbbc5..119a0c31d30eed4f 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -55,7 +55,6 @@ static const struct rpc_call_ops nlmsvc_grant_ops;
> static LIST_HEAD(nlm_blocked);
> static DEFINE_SPINLOCK(nlm_blocked_lock);
>
> -#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
> static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
> {
> /*
> @@ -82,7 +81,6 @@ static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
>
> return buf;
> }
> -#endif
>
> /*
> * Insert a blocked lock into the global list
> diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
> index f6aeed07fe04e3d5..76539c6673f2fb15 100644
> --- a/include/linux/sunrpc/debug.h
> +++ b/include/linux/sunrpc/debug.h
> @@ -67,9 +67,9 @@ do { \
> # define RPC_IFDEBUG(x) x
> #else
> # define ifdebug(fac) if (0)
> -# define dfprintk(fac, fmt, ...) do {} while (0)
> -# define dfprintk_cont(fac, fmt, ...) do {} while (0)
> -# define dfprintk_rcu(fac, fmt, ...) do {} while (0)
> +# define dfprintk(fac, fmt, ...) no_printk(fmt, ##__VA_ARGS__)
> +# define dfprintk_cont(fac, fmt, ...) no_printk(fmt, ##__VA_ARGS__)
> +# define dfprintk_rcu(fac, fmt, ...) no_printk(fmt, ##__VA_ARGS__)
> # define RPC_IFDEBUG(x)
> #endif
>

Acked-by: Jeff Layton <jlayton@kernel.org>