Commit cf2fde7b authored by Rusty Russell's avatar Rusty Russell
Browse files

param: fix module param locks when !CONFIG_SYSFS. 



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: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 38183b9c

include/linux/module.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

kernel/module.c

+8 −1
Original line number Diff line number Diff line
@@ -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. */

kernel/params.c

+14 −4
Original line number Diff line number Diff line
@@ -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);