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Subject[PATCH] Delegate unknown module parameters to interested parties
Date
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, &param, &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);
+ return NOTIFY_STOP_MASK | (NOTIFY_OK - ret);
+ }
+
+ return NOTIFY_OK;
+}
+
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,
--
1.7.2.3


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