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@gmail.com> --- 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