[PATCH v6 19/24] dyndbg: pin class param storage to u32
From: Jim Cromie <jim.cromie@gmail.com>
Date: 2026-07-08 02:19:09
Also in:
dri-devel, linux-arch, linux-doc, lkml
Subsystem:
drm drivers, drm drivers and misc gpu patches, dynamic debug, library code, the rest · Maintainers:
David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Jason Baron, Jim Cromie, Andrew Morton, Linus Torvalds
Currently, `struct ddebug_class_param` uses pointers to `unsigned
long` values which store the state of `bits` and `lvl`, so it changes
sizes depending upon the architecture. Make it always u32 for
consistency.
The bits field references __drm_debug, which was unsigned int, before
commit f158936b60a7 ("drm: POC drm on dyndbg - use in core, 2 helpers, 3 drivers.")
changed it to unsigned long. This patch changes it back.
That enlargement was a thinko; although modules can have up to 63
classes, and *could* have all those classes in a single classmap, the
real reason is to support multiple classmaps (with non-overlapping
class-id ranges).
32 bits is a practical limit for a class-param's usability since all
classes are set together with a single write of a hex value; 16 would
be a realistic limit, drm.debug has ~12 classes.
#> echo 0x0fff > /sys/module/drm/parameters/debug
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v5: u32 for all arches
v4: undo change struct ddebug_class_param to _ddebug_class_param
v3:
fix undefd behavior when classmaps is all 64 bits.
change module_param_named( type-arg from ulong to ullong)
change struct ddebug_class_param to _ddebug_class_param
in drivers/gpu/drm/drm_print.{c,h}
api change later
v2:
patch was "make bits & lvl same size"
but that size was unsigned long, only 32 bits on i386 etc
use u64 for all bits, and %llu %llx
u64-fix
u64-drm-dbg
---
drivers/gpu/drm/drm_print.c | 4 ++--
include/drm/drm_print.h | 2 +-
include/linux/dynamic_debug.h | 4 ++--
lib/dynamic_debug.c | 35 +++++++++++++++++++----------------
lib/test_dynamic_debug.c | 2 +-
5 files changed, 25 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index ded9461df5f2..711ae6606c6e 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c@@ -40,7 +40,7 @@ * __drm_debug: Enable debug output. * Bitmask of DRM_UT_x. See include/drm/drm_print.h for details. */ -unsigned long __drm_debug; +u32 __drm_debug; EXPORT_SYMBOL(__drm_debug); MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
@@ -54,7 +54,7 @@ MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug cat "\t\tBit 8 (0x100) will enable DP messages (displayport code)"); #if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG) -module_param_named(debug, __drm_debug, ulong, 0600); +module_param_named(debug, __drm_debug, uint, 0600); #else /* classnames must match vals of enum drm_debug_category */ DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index ab017b05e175..ed7ce7d7b74c 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h@@ -39,7 +39,7 @@ struct drm_device; struct seq_file; /* Do *not* use outside of drm_print.[ch]! */ -extern unsigned long __drm_debug; +extern u32 __drm_debug; /** * DOC: print
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index d164a24dece1..250b8391cb14 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h@@ -105,8 +105,8 @@ struct _ddebug_info { struct ddebug_class_param { union { - unsigned long *bits; - unsigned int *lvl; + u32 *bits; + u32 *lvl; }; char flags[8]; const struct ddebug_class_map *map;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index d99c69b9ad12..af05f4ae3b55 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c@@ -582,6 +582,7 @@ static int ddebug_exec_query(char *query_string, const char *modname) pr_err("query parse failed\n"); return -EINVAL; } + /* actually go and implement the change */ nfound = ddebug_change(&query, &modifiers); v3pr_info_dq(&query, nfound ? "applied" : "no-match");
@@ -632,8 +633,7 @@ static int ddebug_exec_queries(char *query, const char *modname) /* apply a new class-param setting */ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp, - const unsigned long *new_bits, - const unsigned long old_bits, + const u32 *new_bits, const u32 old_bits, const char *query_modname) { #define QUERY_SIZE 128
@@ -643,24 +643,27 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp, int bi, ct; if (*new_bits != old_bits) - v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits, + v2pr_info("apply bitmap: 0x%x to: 0x%x for %s\n", *new_bits, old_bits, query_modname ?: "'*'"); for (bi = 0; bi < map->length; bi++) { - if (test_bit(bi, new_bits) == test_bit(bi, &old_bits)) + bool new_b = !!(*new_bits & BIT(bi)); + bool old_b = !!(old_bits & BIT(bi)); + + if (new_b == old_b) continue; snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_names[bi], - test_bit(bi, new_bits) ? '+' : '-', dcp->flags); + new_b ? '+' : '-', dcp->flags); ct = ddebug_exec_queries(query, query_modname); matches += ct; - v2pr_info("bit_%d: %d matches on class: %s -> 0x%lx\n", bi, + v2pr_info("bit_%d: %d matches on class: %s -> 0x%x\n", bi, ct, map->class_names[bi], *new_bits); } if (*new_bits != old_bits) - v2pr_info("applied bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits, + v2pr_info("applied bitmap: 0x%x to: 0x%x for %s\n", *new_bits, old_bits, query_modname ?: "'*'"); return matches;
@@ -669,7 +672,7 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp, /* stub to later conditionally add "$module." prefix where not already done */ #define KP_NAME(kp) kp->name -#define CLASSMAP_BITMASK(width) ((1UL << (width)) - 1) +#define CLASSMAP_BITMASK(width) ((width) >= 32 ? ~0U : (1U << (width)) - 1) /** * param_set_dyndbg_classes - class FOO >control
@@ -689,10 +692,10 @@ static int param_set_dyndbg_module_classes(const char *instr, { const struct ddebug_class_param *dcp = kp->arg; const struct ddebug_class_map *map = dcp->map; - unsigned long inrep, new_bits, old_bits; + u32 inrep, new_bits, old_bits; int rc, totct = 0; - rc = kstrtoul(instr, 0, &inrep); + rc = kstrtou32(instr, 0, &inrep); if (rc) { int len = strcspn(instr, "\n"); pr_err("expecting numeric input, not: %.*s > %s\n",
@@ -704,24 +707,24 @@ static int param_set_dyndbg_module_classes(const char *instr, case DD_CLASS_TYPE_DISJOINT_BITS: /* expect bits. mask and warn if too many */ if (inrep & ~CLASSMAP_BITMASK(map->length)) { - pr_warn("%s: input: 0x%lx exceeds mask: 0x%lx, masking\n", + pr_warn("%s: input: 0x%x exceeds mask: 0x%x, masking\n", KP_NAME(kp), inrep, CLASSMAP_BITMASK(map->length)); inrep &= CLASSMAP_BITMASK(map->length); } - v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp)); + v2pr_info("bits:0x%x > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp)); totct += ddebug_apply_class_bitmap(dcp, &inrep, *dcp->bits, mod_name); *dcp->bits = inrep; break; case DD_CLASS_TYPE_LEVEL_NUM: /* input is bitpos, of highest verbosity to be enabled */ if (inrep > map->length) { - pr_warn("%s: level:%ld exceeds max:%d, clamping\n", + pr_warn("%s: level:%u exceeds max:%d, clamping\n", KP_NAME(kp), inrep, map->length); inrep = map->length; } old_bits = CLASSMAP_BITMASK(*dcp->lvl); new_bits = CLASSMAP_BITMASK(inrep); - v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, KP_NAME(kp)); + v2pr_info("lvl:%u bits:0x%x > %s\n", inrep, new_bits, KP_NAME(kp)); totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, mod_name); *dcp->lvl = inrep; break;
@@ -767,9 +770,9 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp) switch (map->map_type) { case DD_CLASS_TYPE_DISJOINT_BITS: - return scnprintf(buffer, PAGE_SIZE, "0x%lx\n", *dcp->bits); + return scnprintf(buffer, PAGE_SIZE, "0x%x\n", *dcp->bits); case DD_CLASS_TYPE_LEVEL_NUM: - return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl); + return scnprintf(buffer, PAGE_SIZE, "%u\n", *dcp->lvl); default: return -1; }
diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
index 74d183ebf3e0..9e8e028461ad 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c@@ -40,7 +40,7 @@ module_param_cb(do_prints, ¶m_ops_do_prints, NULL, 0600); * - tie together sysname, mapname, bitsname, flagsname */ #define DD_SYS_WRAP(_model, _flags) \ - static unsigned long bits_##_model; \ + static u32 bits_##_model; \ static struct ddebug_class_param _flags##_model = { \ .bits = &bits_##_model, \ .flags = #_flags, \
--
2.55.0