The is_odd(dp->zhandle) property is apparently reliable;
BUG_ONs in HEAD~1 demonstrate it.
But is_odd(dp->modname) is also sometimes true, at least when it
points into the __dyndbg section, which has been packed by the linker.
This means the (dp->zhandle % 2) test couldnt distinguish between the
2 values shared in the union. Happily, it blew up, challenging
assumptions. 'gdb> p *dp' confirmed the odd pointer.
Breakpoint 1, dynamic_emit_prefix (dp=0xffffffff8276e190 <__UNIQUE_ID_ddebug429.11>,
buf=0xffffc90000013d48 "߇]\201\377\377\377\377") at ../lib/dynamic_debug.c:598
598 *buf = '\0';
1: dp = (struct _ddebug *) 0xffffffff8276e190 <__UNIQUE_ID_ddebug429.11>
2: *dp = {{is_zhandle = 0, {zhandle = 18446744071599650201, {modname = 0xffffffff823d7599 "intel_idle",
function = 0xffffffff820d8b20 <__func__.7> "intel_idle_init",
filename = 0xffffffff823d75a4 "drivers/idle/intel_idle.c",
format = 0xffffffff823d74e8 "Please enable MWAIT in BIOS SETUP\n", lineno = 1609, flags = 1, key = {
dd_key_true = {key = {enabled = {counter = 1}, {type = 18446744071600203817,
entries = 0xffffffff8245e829, next = 0xffffffff8245e829}}}, dd_key_false = {key = {enabled = {
counter = 1}, {type = 18446744071600203817, entries = 0xffffffff8245e829,
next = 0xffffffff8245e829}}}}}}}}
So instead, add an explicit flag-int: is_zhandle, to remember when the
union is changed to zhandle.
Again, we abuse indenting to minimize whitespace, and add an anonymous
outer struct to contain is_zhandle, and previous contents.
Maybe this flag can be hidden somewhere else; splitting struct _ddebug
into parts is still needed (flags cant be in zram for non-JUMP_LABEL
builds), so maybe it ends up there.
Or perhaps the linker can be convinced to be slightly less
parsimonious with the ram, making this is_odd() test viable.
Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
include/linux/dynamic_debug.h | 5 +++++
lib/dynamic_debug.c | 17 ++++++++++++++---
2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index d23f283fff70..345e86e23bb9 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -13,6 +13,10 @@
*/
struct _ddebug {
struct {
+ int is_zhandle;
+ //
+ union {
+ //struct {
long unsigned int zhandle;
struct {
/*
@@ -48,6 +52,7 @@ struct _ddebug {
} key;
#endif
};}; // struct union
+ }; // struct
} __attribute__((aligned(8)));
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 96252ffacb77..6e93b19bf141 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -602,13 +602,22 @@ static char *dynamic_emit_prefix( struct _ddebug *dp, char *buf)
if (!dp->zhandle) {
/* without union, happens until late-init */
pr_err("nul zhandle: %s.%s\n", dp->modname, dp->function);
- } else if (dp->zhandle % 2) {
+ }
+ else if (dp->is_zhandle) {
+ pr_err("is-zhandle:%d zhandle.mod2:%d\n", dp->is_zhandle, (int)dp->zhandle % 2);
+ v3pr_info("get zhandle: %s.%s\n", dp->modname, dp->function);
+ desc = ddebug_zrec_get(dp->zhandle);
+ v3pr_info("got zhandle: %s.%s\n", desc->modname, desc->function);
+ }
+ else if (dp->zhandle % 2) {
+ pr_err("odd zhandle get %lu %p\n", dp->zhandle, (void*)dp->zhandle);
/* normal ops, after zpool filled
zhandle is odd to distinguish from pointer
- */
+
desc = ddebug_zrec_get(dp->zhandle);
v3pr_info("get zhandle: %s.%s\n",
desc->modname, desc->function);
+ */
} else
/* with union, happens until late-init */
pr_err("some transitional state: %s.%s %lu\n",
@@ -639,7 +648,7 @@ static char *dynamic_emit_prefix( struct _ddebug *dp, char *buf)
if (!dp->zhandle) {
pr_err("Nul zhandle: %s.%s\n", desc->modname, desc->function);
- } else if (dp->zhandle % 2) {
+ } else if (dp->is_zhandle) {
v2pr_info("put zhandle: %s.%s\n", desc->modname, desc->function);
ddebug_zrec_put(dp->zhandle);
}
@@ -1014,6 +1023,8 @@ static void ddebug_zpool_add(struct _ddebug *dp)
*/
dp->zhandle = handle + 1;
+ dp->is_zhandle = 1; /* sanity check on everything else */
+
cursor = (struct _ddebug *)
zs_map_object(dd_callsite_zpool, handle, ZS_MM_WO);
--
2.26.2
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