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param: fix module param locks when !CONFIG_SYSFS.

Browse source 
As Dan Streetman points out, the entire point of locking for is to
stop sysfs accesses, so they're elided entirely in the !SYSFS case.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2015-06-26 06:44:38 +09:30
parent 38183b9c31
commit cf2fde7b39
3 changed files with 24 additions and 5 deletions
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2
include/linux/module.h
View file

@ -240,7 +240,9 @@ struct module {
unsigned int num_syms;
/* Kernel parameters. */
#ifdef CONFIG_SYSFS
struct mutex param_lock;
#endif
struct kernel_param *kp;
unsigned int num_kp;

9
kernel/module.c
View file

@ -1820,6 +1820,10 @@ static void mod_sysfs_fini(struct module *mod)
mod_kobject_put(mod);
}
static void init_param_lock(struct module *mod)
{
mutex_init(&mod->param_lock);
}
#else /* !CONFIG_SYSFS */
static int mod_sysfs_setup(struct module *mod,
@ -1842,6 +1846,9 @@ static void del_usage_links(struct module *mod)
{
}
static void init_param_lock(struct module *mod)
{
}
#endif /* CONFIG_SYSFS */
static void mod_sysfs_teardown(struct module *mod)
@ -3442,7 +3449,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
if (err)
goto unlink_mod;
mutex_init(&mod->param_lock);
init_param_lock(mod);
/* Now we've got everything in the final locations, we can
* find optional sections. */

18
kernel/params.c
View file

@ -25,12 +25,22 @@
#include <linux/slab.h>
#include <linux/ctype.h>
#ifdef CONFIG_SYSFS
/* Protects all built-in parameters, modules use their own param_lock */
static DEFINE_MUTEX(param_lock);
/* Use the module's mutex, or if built-in use the built-in mutex */
#define KPARAM_MUTEX(mod) ((mod) ? &(mod)->param_lock : &param_lock)
#define KPARAM_IS_LOCKED(mod) mutex_is_locked(KPARAM_MUTEX(mod))
static inline void check_kparam_locked(struct module *mod)
{
BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
}
#else
static inline void check_kparam_locked(struct module *mod)
{
}
#endif /* !CONFIG_SYSFS */
/* This just allows us to keep track of which parameters are kmalloced. */
struct kmalloced_param {
@ -459,7 +469,7 @@ static int param_array(struct module *mod,
/* nul-terminate and parse */
save = val[len];
((char *)val)[len] = '\0';
BUG_ON(!KPARAM_IS_LOCKED(mod));
check_kparam_locked(mod);
ret = set(val, &kp);
if (ret != 0)
@ -496,7 +506,7 @@ static int param_array_get(char *buffer, const struct kernel_param *kp)
if (i)
buffer[off++] = ',';
p.arg = arr->elem + arr->elemsize * i;
BUG_ON(!KPARAM_IS_LOCKED(p.mod));
check_kparam_locked(p.mod);
ret = arr->ops->get(buffer + off, &p);
if (ret < 0)
return ret;
@ -616,6 +626,7 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
#define __modinit __init
#endif
#ifdef CONFIG_SYSFS
void kernel_param_lock(struct module *mod)
{
mutex_lock(KPARAM_MUTEX(mod));
@ -626,7 +637,6 @@ void kernel_param_unlock(struct module *mod)
mutex_unlock(KPARAM_MUTEX(mod));
}
#ifdef CONFIG_SYSFS
EXPORT_SYMBOL(kernel_param_lock);
EXPORT_SYMBOL(kernel_param_unlock);