dyndbg: cleanup dynamic usage in ib_srp.c

Currently, in dynamic_debug.h we only provide
DEFINE_DYNAMIC_DEBUG_METADATA() and DYNAMIC_DEBUG_BRANCH()
definitions if CONFIG_DYNAMIC_CORE is enabled. Thus, drivers
such as infiniband srp (see: drivers/infiniband/ulp/srp/ib_srp.c)
must provide their own definitions for !CONFIG_DYNAMIC_CORE.

Thus, let's move this !CONFIG_DYNAMIC_CORE case into dynamic_debug.h.
However, the dynamic debug interfaces should really only be defined
if CONFIG_DYNAMIC_DEBUG is set or CONFIG_DYNAMIC_CORE is set along
with DYNAMIC_DEBUG_MODULE, (see:
Documentation/admin-guide/dynamic-debug-howto.rst). Thus, the
undefined case becomes: !((CONFIG_DYNAMIC_DEBUG ||
(CONFIG_DYNAMIC_CORE && DYNAMIC_DEBUG_MODULE)).
With those changes in place, we can remove the !CONFIG_DYNAMIC_CORE
case from ib_srp.c

This change was prompted by a build breakeage in ib_srp.c stemming
from the inclusion of dynamic_debug.h unconditionally in module.h, due
to commit 7deabd674988 ("dyndbg: use the module notifier callbacks").
In that case, if we have CONFIG_DYNAMIC_CORE=y and
CONFIG_DYNAMIC_DEBUG=n then the definitions for
DEFINE_DYNAMIC_DEBUG_METADATA() and DYNAMIC_DEBUG_BRANCH() are defined
once in ib_srp.c and then again in the dynamic_debug.h. This had been
working prior to the above referenced commit because dynamic_debug.h
was only pulled into ib_srp.c conditinally via printk.h if
CONFIG_DYNAMIC_DEBUG was set.

Also, the exported functions in lib/dynamic_debug.c itself may
not have a prototype if CONFIG_DYNAMIC_DEBUG=n and
CONFIG_DYNAMIC_CORE=y. This would trigger the -Wmissing-prototypes
warning.

The exported functions are behind (include/linux/dynamic_debug.h):

if defined(CONFIG_DYNAMIC_DEBUG) || \
 (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))

Thus, by adding -DDYNAMIC_CONFIG_MODULE to the lib/Makefile we
can ensure that the exported functions have a prototype in all cases,
since lib/dynamic_debug.c is built whenever
CONFIG_DYNAMIC_DEBUG_CORE=y.

Fixes: 7deabd674988 ("dyndbg: use the module notifier callbacks")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303071444.sIbZTDCy-lkp@intel.com/
Signed-off-by: Jason Baron <jbaron@akamai.com>
[mcgrof: adjust commit log, and remove urldefense from URL]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

3 files changed, 40 insertions, 27 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index df21b30b7735..40ba2c6927c6 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -62,11 +62,6 @@ MODULE_AUTHOR("Roland Dreier");
 MODULE_DESCRIPTION("InfiniBand SCSI RDMA Protocol initiator");
 MODULE_LICENSE("Dual BSD/GPL");
 
-#if !defined(CONFIG_DYNAMIC_DEBUG)
-#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)
-#define DYNAMIC_DEBUG_BRANCH(descriptor) false
-#endif
-
 static unsigned int srp_sg_tablesize;
 static unsigned int cmd_sg_entries;
 static unsigned int indirect_sg_entries;
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index f401414341fb..061dd84d09f3 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -128,14 +128,16 @@ struct ddebug_class_param {
 	const struct ddebug_class_map *map;
 };
 
-#if defined(CONFIG_DYNAMIC_DEBUG_CORE)
+/*
+ * pr_debug() and friends are globally enabled or modules have selectively
+ * enabled them.
+ */
+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+	(defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
 
 extern __printf(2, 3)
 void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...);
 
-extern int ddebug_dyndbg_module_param_cb(char *param, char *val,
-					const char *modname);
-
 struct device;
 
 extern __printf(3, 4)
@@ -284,10 +286,6 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 				   KERN_DEBUG, prefix_str, prefix_type,	\
 				   rowsize, groupsize, buf, len, ascii)
 
-struct kernel_param;
-int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp);
-int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp);
-
 /* for test only, generally expect drm.debug style macro wrappers */
 #define __pr_debug_cls(cls, fmt, ...) do {			\
 	BUILD_BUG_ON_MSG(!__builtin_constant_p(cls),		\
@@ -295,23 +293,14 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp);
 	dynamic_pr_debug_cls(cls, fmt, ##__VA_ARGS__);		\
 	} while (0)
 
-#else /* !CONFIG_DYNAMIC_DEBUG_CORE */
+#else /* !(CONFIG_DYNAMIC_DEBUG || (CONFIG_DYNAMIC_DEBUG_CORE && DYNAMIC_DEBUG_MODULE)) */
 
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/printk.h>
 
-static inline int ddebug_dyndbg_module_param_cb(char *param, char *val,
-						const char *modname)
-{
-	if (!strcmp(param, "dyndbg")) {
-		/* avoid pr_warn(), which wants pr_fmt() fully defined */
-		printk(KERN_WARNING "dyndbg param is supported only in "
-			"CONFIG_DYNAMIC_DEBUG builds\n");
-		return 0; /* allow and ignore */
-	}
-	return -EINVAL;
-}
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)
+#define DYNAMIC_DEBUG_BRANCH(descriptor) false
 
 #define dynamic_pr_debug(fmt, ...)					\
 	do { if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); } while (0)
@@ -324,14 +313,40 @@ static inline int ddebug_dyndbg_module_param_cb(char *param, char *val,
 				rowsize, groupsize, buf, len, ascii);	\
 	} while (0)
 
+#endif /* CONFIG_DYNAMIC_DEBUG || (CONFIG_DYNAMIC_DEBUG_CORE && DYNAMIC_DEBUG_MODULE) */
+
+
+#ifdef CONFIG_DYNAMIC_DEBUG_CORE
+
+extern int ddebug_dyndbg_module_param_cb(char *param, char *val,
+					const char *modname);
+struct kernel_param;
+int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp);
+int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp);
+
+#else
+
+static inline int ddebug_dyndbg_module_param_cb(char *param, char *val,
+						const char *modname)
+{
+	if (!strcmp(param, "dyndbg")) {
+		/* avoid pr_warn(), which wants pr_fmt() fully defined */
+		printk(KERN_WARNING "dyndbg param is supported only in "
+			"CONFIG_DYNAMIC_DEBUG builds\n");
+		return 0; /* allow and ignore */
+	}
+	return -EINVAL;
+}
+
 struct kernel_param;
 static inline int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
 { return 0; }
 static inline int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
 { return 0; }
 
-#endif /* !CONFIG_DYNAMIC_DEBUG_CORE */
+#endif
+
 
 extern const struct kernel_param_ops param_ops_dyndbg_classes;
 
-#endif
+#endif /* _DYNAMIC_DEBUG_H */
diff --git a/lib/Makefile b/lib/Makefile
index baf2821f7a00..7afcd85f78f6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -231,6 +231,9 @@ lib-$(CONFIG_GENERIC_BUG) += bug.o
 obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
 
 obj-$(CONFIG_DYNAMIC_DEBUG_CORE) += dynamic_debug.o
+#ensure exported functions have prototypes
+CFLAGS_dynamic_debug.o := -DDYNAMIC_DEBUG_MODULE
+
 obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o
 
 obj-$(CONFIG_NLATTR) += nlattr.o