DEFINE_DYNAMIC_DEBUG_CATEGORIES(name, var, bitmap_desc, @bit_descs) allows users to define a drm.debug style (bitmap) sysfs interface, and to specify the desired mapping from bits[0-N] to the format-prefix'd pr_debug()s to be controlled.
DEFINE_DYNAMIC_DEBUG_CATEGORIES(debug_gvt, __gvt_debug, "i915/gvt bitmap desc", /** * search-prefixes, passed to dd-exec_queries * defines bits 0-N in order. * leading ^ is tacitly inserted (by callback currently) * trailing space used here excludes subcats. * helper macro needs more work * macro to autogen ++$i, 0x%x$i ? */ _DD_cat_("gvt:cmd: "), _DD_cat_("gvt:core: "), _DD_cat_("gvt:dpy: "), _DD_cat_("gvt:el: "), _DD_cat_("gvt:irq: "), _DD_cat_("gvt:mm: "), _DD_cat_("gvt:mmio: "), _DD_cat_("gvt:render: "), _DD_cat_("gvt:sched: "));
dynamic_debug.c: add 3 new elements:
- int param_set_dyndbg() - int param_get_dyndbg() - struct kernel_param_ops param_ops_dyndbg
Following the model of kernel/params.c STANDARD_PARAM_DEFS, All 3 are non-static and exported.
dynamic_debug.h:
Add DEFINE_DYNAMIC_DEBUG_CATEGORIES() described above, and a do-nothing stub.
Note that it also calls MODULE_PARM_DESC for the user, but expects the user to catenate all the bit-descriptions together (as is done in drm.debug), and in the following uses in amdgpu, i915.
This in the hope that someone can offer an auto-incrementing label-generating macro, producing "\tbit-4 0x10\t" etc, and can show how to apply it to __VA_ARGS__.
Also extern the struct kernel_param param_ops_dyndbg symbol, as is done in moduleparams.h for all the STANDARD params.
USAGE NOTES:
Using dyndbg to query on "format ^$prefix" requires that the prefix be present in the compiled-in format string; where run-time prefixing is used, that format would be "%s...", which is not usefully selectable.
Adding structural query terms (func,file,lineno) could help (module is already done), but DEFINE_DYNAMIC_DEBUG_CATEGORIES can't do that now, adding it needs a better reason imo.
Dyndbg is completely agnostic wrt the categorization scheme used, to play well with any prefix convention already in use. Ad-hoc categories and sub-categories are implicitly allowed, author discipline and review is expected.
Here are some examples:
"1","2","3" 2 doesn't imply 1. otherwize, sorta like printk levels "1:","2:","3:" are better, avoiding [1-9]\d+ ambiguity "hi:","mid:","low:" are reasonable, and imply independence "todo:","rfc:","fixme:" might be handy "A:".."Z:" uhm, yeah
Hierarchical classes/categories are natural:
"drm:<CAT>:" is used in later commit "drm:<CAT>:<SUB>:" is a natural extension. "drm:atomic:fail:" has been proposed, sounds directly useful
Some properties of a hierarchical category deserve explication:
Trailing spaces matter !
With 1..3-space ("drm: ", "drm:atomic: ", "drm:atomic:fail: "), the ":" doesn't terminate the search-space, the trailing space does. So a "drm:" search spec will match all DRM categories & subcategories, and will not be useful in an interface where all categories are already controlled together. That said, "drm:atomic:" & "drm:atomic: " are different, and both are useful in cases.
Ad-Hoc sub-categories:
These have a caveat wrt wrapper macros adding prefixes like "drm:atomic: "; the trailing space in the prefix means that drm_dbg_atomic("fail: ...") pastes as "drm:atomic: fail: ", which obviously isn't ideal wrt clear and simple bitmaps.
A possible solution is to have a FOO_() version of every FOO() macro which (anti-mnemonically) elides the trailing space, which is normally inserted by a modified FOO(). Doing this would enforce a policy decision that "debug categories will be space terminated", with an pressure-relief valve.
Summarizing:
- "drm:kms: " & "drm:kms:" are different - "drm:kms" also different - includes drm:kms2: - "drm:kms:\t" also different - "drm:kms:*" doesn't work, no wildcard on format atm.
Order matters in DEFINE_DYNAMIC_DEBUG_CATEGORIES(... @bit_descs)
@bit_descs (array) position determines the bit mapping to the prefix, so to keep a stable map, new categories or 3rd level categories must be added to the end.
Since bits are/will-stay applied 0-N, the later bits can countermand the earlier ones, but its tricky - consider;
DD_CATs(... "drm:atomic:", "drm:atomic:fail:" ) // misleading
The 1st search-term is misleading, because it includes (modifies) subcategories, but then 2nd overrides it. So don't do that.
For "drm:atomic:fail:" in particular, its best not to add it into an existing bitmap, because the current setting would be lost at every (unrelated) write, and a separate bitmap is much more stable.
There is still plenty of bikeshedding to do.
Signed-off-by: Jim Cromie jim.cromie@gmail.com --- v5: . rename to DEFINE_DYNAMIC_DEBUG_CATEGORIES from DEFINE_DYNDBG_BITMAP . in set_dyndbg, replace hardcoded "i915" w kp->mod->name . static inline the stubs . const *str in structs, const array. - Emil . dyndbg: add do-nothing DEFINE_DYNAMIC_DEBUG_CATEGORIES if !DD_CORE . call MOD_PARM_DESC(name, "$desc") for users . simplify callback, remove bit-change detection . config errs reported by lkp@intel.com
v6: . return rc, bitmap->, snprintf, ws - Andy Shevchenko . s/chgct/matches/ - old varname is misleading . move code off file bottom to a "better" place . change ##fsname to ##var for safer varname construct . workaround for !CONFIG_MODULES . move forward decl down to where its needed --- include/linux/dynamic_debug.h | 52 +++++++++++++++++++++++- lib/dynamic_debug.c | 76 ++++++++++++++++++++++++++++++++--- 2 files changed, 121 insertions(+), 7 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index dce631e678dd..51b7254daee0 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -51,8 +51,6 @@ struct _ddebug { #endif } __attribute__((aligned(8)));
- - #if defined(CONFIG_DYNAMIC_DEBUG_CORE)
/* exported for module authors to exercise >control */ @@ -181,6 +179,10 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, KERN_DEBUG, prefix_str, prefix_type, \ rowsize, groupsize, buf, len, ascii)
+struct kernel_param; +int param_set_dyndbg(const char *instr, const struct kernel_param *kp); +int param_get_dyndbg(char *buffer, const struct kernel_param *kp); + #else /* !CONFIG_DYNAMIC_DEBUG_CORE */
#include <linux/string.h> @@ -227,6 +229,52 @@ static inline int dynamic_debug_exec_queries(const char *query, const char *modn return 0; }
+static inline int param_set_dyndbg(const char *instr, const struct kernel_param *kp) + { return 0; } +static inline int param_get_dyndbg(char *buffer, const struct kernel_param *kp) + { return 0; } + #endif /* !CONFIG_DYNAMIC_DEBUG_CORE */
+struct dyndbg_bitdesc { + /* bitpos is inferred from index in containing array */ + const char *prefix; + const char *help; +}; + +#if defined(CONFIG_DYNAMIC_DEBUG) || \ + (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE)) +/** + * DEFINE_DYNAMIC_DEBUG_CATEGORIES() - define debug categories, bitmap, sysfs-knob + * @fsname: parameter basename under /sys + * @var: C-identifier holding state + * @_desc: string summarizing the controls provided + * @...: list of struct dyndbg_bitdesc initializations + * + * Defines /sys/modules/$modname/parameters/@fsname, and @bit_descs, + * which maps bits 0-N to categories of pr_debugs to be controlled. + * This is effectively write only, because controlled callsites can be + * further modified via >control. + * + * Also calls MODULE_PARM_DESC(fsname, _desc), with the intent to + * generate the bit_legend and apply it to the given bit_descs + */ +#define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, _desc, ...) \ + MODULE_PARM_DESC(fsname, _desc); \ + static const struct dyndbg_bitdesc dyndbg_cats_##var[] = \ + { __VA_ARGS__, { NULL, NULL } }; \ + module_param_cb_data(fsname, ¶m_ops_dyndbg, &var, 0644, \ + &dyndbg_cats_##var) + +#define _DD_cat_(pfx) { .prefix = pfx, .help = "help for " pfx } +#define _DD_cat_help_(pfx) "\t " pfx "\t- help for " pfx "\n" + +extern const struct kernel_param_ops param_ops_dyndbg; +#else +#define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, bitmap_desc, ...) \ + MODULE_PARM_DESC(fsname, "auto: " bitmap_desc) +#define _DD_cat_(pfx) +#define _DD_cat_help_(pfx) +#endif + #endif diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index cb5abb42c16a..a43427c67c3f 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -511,10 +511,11 @@ static int ddebug_exec_query(char *query_string, const char *modname) return nfound; }
-/* handle multiple queries in query string, continue on error, return - last error or number of matching callsites. Module name is either - in param (for boot arg) or perhaps in query string. -*/ +/* + * handle multiple queries in query string, continue on error, return + * last error or number of matching callsites. Module name is either + * in param (for boot arg) or perhaps in query string. + */ static int ddebug_exec_queries(char *query, const char *modname) { char *split; @@ -529,7 +530,7 @@ static int ddebug_exec_queries(char *query, const char *modname) if (!query || !*query || *query == '#') continue;
- vpr_info("query %d: "%s"\n", i, query); + vpr_info("query %d: "%s" %s\n", i, query, (modname) ? modname : "");
rc = ddebug_exec_query(query, modname); if (rc < 0) { @@ -577,6 +578,71 @@ int dynamic_debug_exec_queries(const char *query, const char *modname) } EXPORT_SYMBOL_GPL(dynamic_debug_exec_queries);
+#ifdef MODULES +#define KP_MOD_NAME kp->mod->name +#else +#define KP_MOD_NAME NULL /* wildcard */ +#endif +#define FMT_QUERY_SIZE 128 /* typically need <40 */ +/** + * param_set_dyndbg() - drm.debug style bits=>categories setter + * @instr: string echo>d to sysfs + * @kp: struct kernel_param* ->data has bitmap + * Exported to support DEFINE_DYNAMIC_DEBUG_CATEGORIES + */ +int param_set_dyndbg(const char *instr, const struct kernel_param *kp) +{ + unsigned long inbits; + int rc, i, matches = 0, totct = 0; + char query[FMT_QUERY_SIZE]; + const struct dyndbg_bitdesc *bitmap = kp->data; + + if (!bitmap) { + pr_err("set_dyndbg: no bits=>queries map\n"); + return -EINVAL; + } + rc = kstrtoul(instr, 0, &inbits); + if (rc) { + pr_err("set_dyndbg: failed\n"); + return rc; + } + vpr_info("set_dyndbg: input 0x%lx\n", inbits); + + for (i = 0; bitmap->prefix; i++, bitmap++) { + snprintf(query, FMT_QUERY_SIZE, "format '^%s' %cp", bitmap->prefix, + test_bit(i, &inbits) ? '+' : '-'); + + matches = ddebug_exec_queries(query, KP_MOD_NAME); + + v2pr_info("bit-%d: %d matches on '%s'\n", i, matches, query); + totct += matches; + } + vpr_info("total matches: %d\n", totct); + return 0; +} +EXPORT_SYMBOL(param_set_dyndbg); + +/** + * param_get_dyndbg() - drm.debug style bitmap to format-prefix categories + * @buffer: string returned to user via sysfs + * @kp: struct kernel_param* + * Exported to provide required .get interface, not useful. + * pr_debugs may be altered after .set via `echo $foo >control` + */ +int param_get_dyndbg(char *buffer, const struct kernel_param *kp) +{ + return scnprintf(buffer, PAGE_SIZE, "%u\n", + *((unsigned int *)kp->arg)); +} +EXPORT_SYMBOL(param_get_dyndbg); + +const struct kernel_param_ops param_ops_dyndbg = { + .set = param_set_dyndbg, + .get = param_get_dyndbg, +}; +/* support DEFINE_DYNAMIC_DEBUG_CATEGORIES users */ +EXPORT_SYMBOL(param_ops_dyndbg); + #define PREFIX_SIZE 64
static int remaining(int wrote)