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

Geert Uytterhoeven
2023-10-12T10:08:19Z

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

--
2.34.1