[PATCH] Dynamic Debug: Introduce global fake module param module.ddebug
in [Kernel]
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From: Thomas Renninger on 26 Jul 2010 08:20 This patch is based on 2.6.35-rc5 + this patchset I posted recently: [patch 0/3] Dynamic Debug providing early boot debug messages via boot parameter It would be great to see these getting merged into 2.6.36... Thanks, Thomas ----- Dynamic Debug: Introduce global fake module param module.ddebug Dynamic Debug allows enabling of pr_debug or KERN_DEBUG messages at runtime. This is controlled via /sys/kernel/debug/dynamic_debug/control. One major drawback is that the whole initialization of a module cannot be tracked, because ddebug is only aware of debug strings of loaded modules. But this is the most interesting part... This patch introduces a fake module parameter module.ddebug(not shown in /sys/module/*/parameters, thus it does not use any resources/memory). If a module gets ddebug passed as a module parameter (e.g. via module.ddebug kernel boot param or via "modprobe module ddebug"), all debug strings of this module get activated by issuing "module module_name +p" internally (not via sysfs) when the module gets loaded. Possible enhancements for the future if ddebug might get extended with further flags: module.ddebug=flags Then module.ddebug="p" would be the same as module.ddebug, but if there is a "x" ddebug flag added, one could pass: module.ddebug="xp" which would result in such a dynamic debug query: module module_name +xp One not handled side-effect of this patch: Modules must not use "ddebug" module parameter or it will get ignored. I tried to find a compile time check, but I could not see how that is possible. Possibly a run-time check or at least documentation (where?) should get added, that "ddebug" must not get used as a module parameter. Tested with: options hp-wmi ddebug in modprobe.conf.local -> works and pr_debug messages issued at module initialization time show up. Also "p" flag gets set for the whole hp-wmi module debug strings: grep hp-wmi /sys/../dynamic_debug/control Signed-off-by: Thomas Renninger <trenn(a)suse.de> --- include/linux/dynamic_debug.h | 5 +++++ kernel/params.c | 9 ++++++++- lib/dynamic_debug.c | 2 +- 3 files changed, 14 insertions(+), 2 deletions(-) Index: linux-platform_drivers/kernel/params.c =================================================================== --- linux-platform_drivers.orig/kernel/params.c +++ linux-platform_drivers/kernel/params.c @@ -24,6 +24,7 @@ #include <linux/err.h> #include <linux/slab.h> #include <linux/ctype.h> +#include <linux/dynamic_debug.h> #if 0 #define DEBUGP printk @@ -132,7 +133,7 @@ int parse_args(const char *name, unsigned num, int (*unknown)(char *param, char *val)) { - char *param, *val; + char *param, *val, ddebug[1024]; DEBUGP("Parsing ARGS: %s\n", args); @@ -144,6 +145,12 @@ int parse_args(const char *name, int irq_was_disabled; args = next_arg(args, ¶m, &val); + if (parameq(param, "ddebug")) { + sprintf(ddebug, "module %s +p", name); + ddebug_exec_query(ddebug); + continue; + } + irq_was_disabled = irqs_disabled(); ret = parse_one(param, val, params, num, unknown); if (irq_was_disabled && !irqs_disabled()) { Index: linux-platform_drivers/include/linux/dynamic_debug.h =================================================================== --- linux-platform_drivers.orig/include/linux/dynamic_debug.h +++ linux-platform_drivers/include/linux/dynamic_debug.h @@ -41,6 +41,7 @@ int ddebug_add_module(struct _ddebug *ta #if defined(CONFIG_DYNAMIC_DEBUG) extern int ddebug_remove_module(const char *mod_name); +extern int ddebug_exec_query(char *query_string); #define __dynamic_dbg_enabled(dd) ({ \ int __ret = 0; \ @@ -77,6 +78,10 @@ static inline int ddebug_remove_module(c { return 0; } +static inline int ddebug_exec_query(char *query_string) +{ + return 0; +} #define dynamic_pr_debug(fmt, ...) \ do { if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); } while (0) Index: linux-platform_drivers/lib/dynamic_debug.c =================================================================== --- linux-platform_drivers.orig/lib/dynamic_debug.c +++ linux-platform_drivers/lib/dynamic_debug.c @@ -429,7 +429,7 @@ static int ddebug_parse_flags(const char return 0; } -static int ddebug_exec_query(char *query_string) +int ddebug_exec_query(char *query_string) { unsigned int flags = 0, mask = 0; struct ddebug_query query; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |