[PATCH v6 1/2] sunrpc: simplify dprintk macros and cleanup redundant debug guards

[Sean Chang]

When CONFIG_SUNRPC_DEBUG is disabled, the dfprintk() macros currently
expand to empty do-while loops. This causes variables used solely
within these calls to appear unused, triggering -Wunused-variable
warnings.

Following David Laight's suggestion, simplify the macro definitions by
removing the unnecessary 'fmt' argument and using no_printk(__VA_ARGS__)
directly. This ensures the compiler performs type checking and "sees"
the variables, silencing the warnings without emitting any code.

Verification with .lst files under -O2 confirms that the compiler
successfully performs "dead code elimination". Even when variables
(like char buf[] in nfsfh.c) or static helper functions (like
nlmdbg_cookie2a in svclock.c) are declared without #ifdef, they are
completely optimized out (no stack allocation, no symbol references in
the final executable) as they are only referenced within no_printk().

This allows for significant cleanup:
- Remove RPC_IFDEBUG() and associated #if blocks in fs/nfsd/nfsfh.c
  and net/sunrpc/xprtrdma/svc_rdma_transport.c.
- Remove the #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) guard around
  nlmdbg_cookie2a in fs/lockd/svclock.c.
- Consolidate the dprintk definition to be more idiomatic.

This fixes the build errors reported by the kernel test robot while
improving code maintainability.

Link: https://lore.kernel.org/all/69a2e269.050a0220.3a55be.003e.GAE@xxxxxxxxxx/
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202603010612.uRmHYMsi-lkp@xxxxxxxxx/
Closes: https://lore.kernel.org/oe-kbuild-all/202603010852.3RKXCwyF-lkp@xxxxxxxxx/
Closes: https://lore.kernel.org/oe-kbuild-all/202603010808.w3TtG6fC-lkp@xxxxxxxxx/
Suggested-by: Andrew Lunn <andrew@xxxxxxx>
Suggested-by: David Laight <david.laight.linux@xxxxxxxxx>
Signed-off-by: Sean Chang <seanwascoding@xxxxxxxxx>
---
 fs/lockd/svclock.c                       | 2 --
 fs/nfsd/nfsfh.c                          | 2 +-
 include/linux/sunrpc/debug.h             | 6 ++----
 net/sunrpc/xprtrdma/svc_rdma_transport.c | 4 +---
 4 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 255a847ca0b6..4bac32f009f6 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -53,7 +53,6 @@ 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)
 {
 	/*
@@ -80,7 +79,6 @@ static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
 
 	return buf;
 }
-#endif
 
 /*
  * Insert a blocked lock into the global list
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index ed85dd43da18..cb3fb91d18c0 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -105,7 +105,7 @@ static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
 {
 	/* Check if the request originated from a secure port. */
 	if (rqstp && !nfsd_originating_port_ok(rqstp, cred, exp)) {
-		RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
+		char buf[RPC_MAX_ADDRBUFLEN];
 		dprintk("nfsd: request from insecure port %s!\n",
 		        svc_print_addr(rqstp, buf, sizeof(buf)));
 		return nfserr_perm;
diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
index eb4bd62df319..f6f2a106eeaf 100644
--- a/include/linux/sunrpc/debug.h
+++ b/include/linux/sunrpc/debug.h
@@ -49,12 +49,10 @@ do {									\
 	}								\
 } while (0)
 
-# define RPC_IFDEBUG(x)		x
 #else
 # define ifdebug(fac)		if (0)
-# define dfprintk(fac, fmt, ...)	do {} while (0)
-# define dfprintk_rcu(fac, fmt, ...)	do {} while (0)
-# define RPC_IFDEBUG(x)
+# define dfprintk(fac, ...)		no_printk(__VA_ARGS__)
+# define dfprintk_rcu(fac, ...)	no_printk(__VA_ARGS__)
 #endif
 
 /*
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 9b623849723e..ba6fe0fd387d 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -414,7 +414,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	struct ib_qp_init_attr qp_attr;
 	struct ib_device *dev;
 	int ret = 0;
-	RPC_IFDEBUG(struct sockaddr *sap);
+	struct sockaddr *sap;
 
 	listen_rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt);
 	clear_bit(XPT_CONN, &xprt->xpt_flags);
@@ -560,7 +560,6 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 		goto errout;
 	}
 
-#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 	dprintk("svcrdma: new connection accepted on device %s:\n", dev->name);
 	sap = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
 	dprintk("    local address   : %pIS:%u\n", sap, rpc_get_port(sap));
@@ -571,7 +570,6 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	dprintk("    rdma_rw_ctxs    : %d\n", ctxts);
 	dprintk("    max_requests    : %d\n", newxprt->sc_max_requests);
 	dprintk("    ord             : %d\n", conn_param.initiator_depth);
-#endif
 
 	return &newxprt->sc_xprt;
 
-- 
2.34.1