linux-kernel - [RFC PATCH v6 29/34] dyndbg: RFC drop

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Message-Id: <20210529200029.205306-30-jim.cromie@gmail.com>
Date:   Sat, 29 May 2021 14:00:24 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [RFC PATCH v6 29/34] dyndbg: RFC drop _ddebug.site pointer

Flip the switch on #define SITE_CHK.  This finally removes the
_ddebug.site pointer, and almost all uses of it.  Due to this, the
.site cross-link done by DEFINE_DYNAMIC_DEBUG_METADATA() is lost to
the compiler, so suppress the resulting warnings by adding a "__used"
to the _ddebug_site records initialized there.

In .c, use the union header types introduced in ~HEAD~1,
with some casts sprinkled in.

This seems to work, but should be cleaner.  RFC

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 include/linux/dynamic_debug.h |  4 ++--
 lib/dynamic_debug.c           | 16 ++++++++--------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index c9c568a698a8..b2189ff94fda 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -6,7 +6,7 @@
 #include <linux/jump_label.h>
 #endif
 
-#define SITE_CHK /* include .site pointer and checks on it */
+// #define SITE_CHK /* include .site pointer and checks on it */
 
 #ifdef SITE_CHK
 #define SITE_CHK_(...)		__VA_ARGS__
@@ -135,7 +135,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 			 const char *fmt, ...);
 
 #define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)		\
-	static struct _ddebug_site  __aligned(8)		\
+	static struct _ddebug_site  __aligned(8) __used		\
 	__section("__dyndbg_sites") name##_site = {		\
 		.modname = KBUILD_MODNAME,			\
 		.filename = __FILE__,				\
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index f2f6f2b20d01..0e2e082b487b 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -148,9 +148,11 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 
 static struct _ddebug_site *ddebug_site_get(struct _ddebug *dp)
 {
-	struct _ddebug *dh = dp - (dp->_index);
+	union _ddebug_header *dh = (union _ddebug_header *) (dp - dp->_index);
+
+	if (!is_dyndbg_header_pair(dh, dh->site))
+		v3pr_info("get: header fail on %d-%d\n", dp->_index, dp->lineno);
 
-	BUG_ON(!is_dyndbg_header_pair(dh, dh->site));
 #ifdef SITE_CHK
 	if (dp >= __start___dyndbg && dp < __stop___dyndbg) {
 
@@ -178,7 +180,7 @@ static struct _ddebug_site *ddebug_site_get(struct _ddebug *dp)
 
 	return dp->site;
 #else
-	return &dh->site[dp->_index];
+	return (struct _ddebug_site *) &dh->site[dp->_index];
 #endif
 }
 static inline void ddebug_site_put(struct _ddebug *dp)
@@ -1070,16 +1072,14 @@ static int __ddebug_add_module(struct _ddebug *tab, struct _ddebug_site *sites,
 			       const char *modname)
 {
 	struct ddebug_table *dt;
+	union _ddebug_header *dh = (union _ddebug_header *) &tab[0];
 	int i;
 
 	v3pr_info("add-module: %s.%d sites\n", modname, numdbgs);
 
-	if (numdbgs && is_dyndbg_header_pair(tab, sites)) {
-
-		v3pr_info(" header: %d %s.%s.%d\n", tab[0]._index, modname,
-			  tab[0].site->function, tab[0].lineno);
+	if (numdbgs && is_dyndbg_header_pair(dh, sites)) {
 
-		SITE_CHK_(BUG_ON(tab[0].site != &sites[0]));
+		BUG_ON((void *) &dh->site[0] != (void *) &sites[0]);
 
 		if (numdbgs <= 1) {
 			v3pr_info(" skip header %s\n", modname);
-- 
2.31.1