Dynamic Debug: Introduce global fake module param module.ddebug
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From: Jason Baron on 5 Aug 2010 11:40 On Mon, Jul 26, 2010 at 02:14:30PM +0200, Thomas Renninger wrote: > 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; patch looks pretty good to me. I'm not sure how we reserve the 'ddebug' keyword. However, I think its probably ok, if we mention it in 'kernel-parameters.txt' and in the dynamic debug documentation. Also, ddebug could show up in /sys/module/$(modulename}/parameters/ , but this can probably be done in a followup patch. Also, if 'ddebug' alone is set on the kernel command line, i'd like to see us enable all debug statements. We could implement this by adding a special 'meta' module to the control file which is just has a module name of of 'All' or something like that. This could also be done in a subsequent patch. We also need to at least remove the 'dynamic_printk' doc from kernel-parameters.txt. thanks, -Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jason Baron on 5 Aug 2010 13:30
On Thu, Aug 05, 2010 at 06:05:40PM +0200, Thomas Renninger wrote: > On Thursday 05 August 2010 17:39:10 Jason Baron wrote: > > On Mon, Jul 26, 2010 at 02:14:30PM +0200, Thomas Renninger wrote: > > > This patch is based on 2.6.35-rc5 + this patchset I posted recently: > > > [patch 0/3] Dynamic Debug providing early boot debug messages via > > > boot parameter > > > > > > It would be great to see these getting merged into 2.6.36... > ... > > patch looks pretty good to me. I'm not sure how we reserve the > > 'ddebug' keyword. > Yep, I also was not sure about that. > > However, I think its probably ok, if we mention it > > in 'kernel-parameters.txt' and in the dynamic debug documentation. > I added some documentation to the dynamic debug docu file and posted > the patch again (as a reply on my initial post, should be the same mail > thread). > > > Also, ddebug could show up in /sys/module/$(modulename}/parameters/ , > > but this can probably be done in a followup patch. > This was intentional. > At the time /sys is available one can also use > /sys/kernel/debug/dynamic_debug/control > echo "module my_module_to_debug +p" > >/sys/kernel/debug/dynamic_debug/control > would exactly do the same as /sys/module/$(modulename}/parameters > The advantage of not having it, is it saves quite some resources, in > fact it uses none. > Otherwise every module would have an addtional parameter added with a > sysfs file associated with it with no additional functional gain. > > > Also, if 'ddebug' alone is set on the kernel command line, i'd like to > > see us enable all debug statements. We could implement this by adding > > a special 'meta' module to the control file which is just has a module > > name of of 'All' or something like that. This could also be done in a > > subsequent patch. > Is there a single query which could do it? I don't think so. > If not, possibly a keyword like file/module called "all" could be added. > Then you could simply do that by ddebug_query="all +p" > ok. that makes sense. I would make the all mode apply to all future modules that get loaded as well, just to be clear... > > We also need to at least remove the 'dynamic_printk' doc from > > kernel-parameters.txt. > Don't know about this one. > > So, I have your acked-by for this one? Acked-by: Jason Baron <jbaron(a)redhat.com> > Let's get this pushed into a tree, with some luck it still could make it > into 2.6.36? The other three have been taken by Pekka? He said something > about taking them, but I haven't received any confirmation. > Ah no, he acked-by them only. > > As these are rather general ones, which tree should they go through, > possibly Andrew could take them? > I can resubmit, if someone could tell me a list/maintainer that fits > best, so that they really make it in... > > Thanks, > > Thomas right, originally Greg KH, pulled these into his tree. Greg, can you take a look at pulling these into your tree? So it would be this patch, and the thread: Subject: [patch 0/3] Dynamic Debug providing early boot debug messages via boot parameter thanks, -Jason -- 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/ |