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Date: Tue, 09 Nov 2010 09:39:21 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Yuanhan Liu <yuanhan.liu@...ux.intel.com>,
linux-kernel@...r.kernel.org, fweisbec@...il.com, mingo@...hat.com,
Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [PATCH] Delegate unknown module parameters to interested
parties
[ Added Rusty "Module God" Russell ]
On Tue, 2010-11-09 at 14:11 +0000, Chris Wilson wrote:
> This is a sketch of what I had in mind for trace to do the event
> initialisation on the modules behalf.
>
> ---
> include/linux/module.h | 8 ++++++++
> include/linux/moduleparam.h | 3 ++-
> init/main.c | 8 ++++----
> kernel/module.c | 21 ++++++++++++++++++++-
> kernel/params.c | 10 ++++++----
> kernel/trace/trace_events.c | 15 ++++++++++++++-
> 6 files changed, 54 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/module.h b/include/linux/module.h
> index b29e745..84daad8 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -241,6 +241,14 @@ enum module_state
> MODULE_STATE_GOING,
> };
>
> +#define MODULE_UNKNOWN_PARAM (MODULE_STATE_GOING + 1)
> +
> +struct module_unknown_param {
> + struct module *mod;
> + char *param;
> + char *val;
> +};
> +
> struct module
> {
> enum module_state state;
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> index 112adf8..5e24ec1 100644
> --- a/include/linux/moduleparam.h
> +++ b/include/linux/moduleparam.h
> @@ -265,7 +265,8 @@ extern int parse_args(const char *name,
> char *args,
> const struct kernel_param *params,
> unsigned num,
> - int (*unknown)(char *param, char *val));
> + int (*unknown)(char *param, char *val, void *data),
> + void *data);
>
> /* Called by module remove. */
> #ifdef CONFIG_SYSFS
> diff --git a/init/main.c b/init/main.c
> index e59af24..782780e 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -267,7 +267,7 @@ early_param("loglevel", loglevel);
> * Unknown boot options get handed to init, unless they look like
> * unused parameters (modprobe will find them in /proc/cmdline).
> */
> -static int __init unknown_bootoption(char *param, char *val)
> +static int __init unknown_bootoption(char *param, char *val, void *data)
> {
> /* Change NUL term back to "=", to make "param" the whole string. */
> if (val) {
> @@ -455,7 +455,7 @@ static noinline void __init_refok rest_init(void)
> }
>
> /* Check for early params. */
> -static int __init do_early_param(char *param, char *val)
> +static int __init do_early_param(char *param, char *val, void *data)
> {
> const struct obs_kernel_param *p;
>
> @@ -475,7 +475,7 @@ static int __init do_early_param(char *param, char *val)
>
> void __init parse_early_options(char *cmdline)
> {
> - parse_args("early options", cmdline, NULL, 0, do_early_param);
> + parse_args("early options", cmdline, NULL, 0, do_early_param, NULL);
> }
>
> /* Arch code calls this early on, or if not, just before other parsing. */
> @@ -578,7 +578,7 @@ asmlinkage void __init start_kernel(void)
> parse_early_param();
> parse_args("Booting kernel", static_command_line, __start___param,
> __stop___param - __start___param,
> - &unknown_bootoption);
> + &unknown_bootoption, NULL);
> /*
> * These use large bootmem allocations and must precede
> * kmem_cache_init()
> diff --git a/kernel/module.c b/kernel/module.c
> index 2df4630..87ce541 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -2544,6 +2544,24 @@ static int post_relocation(struct module *mod, const struct load_info *info)
> return module_finalize(info->hdr, info->sechdrs, mod);
> }
>
> +static int unknown_param(char *param, char *val, void *data)
> +{
> + struct module_unknown_param arg;
> + int ret;
> +
> + arg.mod = data;
> + arg.param = param;
> + arg.val = val;
> +
> + ret = blocking_notifier_call_chain(&module_notify_list,
> + MODULE_UNKNOWN_PARAM,
> + &arg);
> + if (ret & NOTIFY_STOP_MASK)
> + return notifier_to_errno(ret);
> +
> + return -ENOENT;
> +}
> +
> /* Allocate and load the module: note that size of section 0 is always
> zero, and we rely on this for optional sections. */
> static struct module *load_module(void __user *umod,
> @@ -2637,7 +2655,8 @@ static struct module *load_module(void __user *umod,
> mutex_unlock(&module_mutex);
>
> /* Module is ready to execute: parsing args may do that. */
> - err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, NULL);
> + err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
> + unknown_param, mod);
> if (err < 0)
> goto unlink;
>
> diff --git a/kernel/params.c b/kernel/params.c
> index 08107d1..d8c707c 100644
> --- a/kernel/params.c
> +++ b/kernel/params.c
> @@ -87,7 +87,8 @@ static int parse_one(char *param,
> char *val,
> const struct kernel_param *params,
> unsigned num_params,
> - int (*handle_unknown)(char *param, char *val))
> + int (*handle_unknown)(char *param, char *val, void *data),
> + void *data)
> {
> unsigned int i;
> int err;
> @@ -109,7 +110,7 @@ static int parse_one(char *param,
>
> if (handle_unknown) {
> DEBUGP("Unknown argument: calling %p\n", handle_unknown);
> - return handle_unknown(param, val);
> + return handle_unknown(param, val, data);
> }
>
> DEBUGP("Unknown argument `%s'\n", param);
> @@ -173,7 +174,8 @@ int parse_args(const char *name,
> char *args,
> const struct kernel_param *params,
> unsigned num,
> - int (*unknown)(char *param, char *val))
> + int (*unknown)(char *param, char *val, void *data),
> + void *data)
> {
> char *param, *val;
>
> @@ -188,7 +190,7 @@ int parse_args(const char *name,
>
> args = next_arg(args, ¶m, &val);
> irq_was_disabled = irqs_disabled();
> - ret = parse_one(param, val, params, num, unknown);
> + ret = parse_one(param, val, params, num, unknown, data);
> if (irq_was_disabled && !irqs_disabled()) {
> printk(KERN_WARNING "parse_args(): option '%s' enabled "
> "irq's!\n", param);
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 0725eea..d23cbf3 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -1330,10 +1330,21 @@ static void trace_module_remove_events(struct module *mod)
> up_write(&trace_event_mutex);
> }
>
> +static int trace_module_unknown_param(struct module_unknown_param *arg)
> +{
> + if (strcmp(arg->param, "trace") == 0) {
> + int ret = trace_set_clr_module_event(arg->mod, arg->val, 1);
This of course assumes that arg->mod is the system. Perhaps I could
rewrite this to only enable events in this module.
> + return NOTIFY_STOP_MASK | (NOTIFY_OK - ret);
> + }
> +
> + return NOTIFY_OK;
> +}
Wow! I was just going to add a direct hook into the module code, but
this is much more generic!
-- Steve
> +
> static int trace_module_notify(struct notifier_block *self,
> unsigned long val, void *data)
> {
> struct module *mod = data;
> + int ret = 0;
>
> mutex_lock(&event_mutex);
> switch (val) {
> @@ -1343,10 +1354,12 @@ static int trace_module_notify(struct notifier_block *self,
> case MODULE_STATE_GOING:
> trace_module_remove_events(mod);
> break;
> + case MODULE_UNKNOWN_PARAM:
> + ret = trace_module_unknown_param(data);
> }
> mutex_unlock(&event_mutex);
>
> - return 0;
> + return ret;
> }
> #else
> static int trace_module_notify(struct notifier_block *self,
--
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