[PATCH] sunrpc: Use no_printk() in dfprintk*() dummies

[Geert Uytterhoeven <geert+renesas@xxxxxxxxx>]

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 uncontionally, 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.

Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
 include/linux/sunrpc/debug.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

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
 
-- 
2.34.1