[RFC PATCH v6 29/34] dyndbg: RFC drop _ddebug.site pointer

Jim Cromie
2021-05-29T20:03:45Z

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@gmail.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