module: add per-module param_lock
Add a "param_lock" mutex to each module, and update params.c to use
the correct built-in or module mutex while locking kernel params.
Remove the kparam_block_sysfs_r/w() macros, replace them with direct
calls to kernel_param_[un]lock(module).
The kernel param code currently uses a single mutex to protect
modification of any and all kernel params. While this generally works,
there is one specific problem with it; a module callback function
cannot safely load another module, i.e. with request_module() or even
with indirect calls such as crypto_has_alg(). If the module to be
loaded has any of its params configured (e.g. with a /etc/modprobe.d/*
config file), then the attempt will result in a deadlock between the
first module param callback waiting for modprobe, and modprobe trying to
lock the single kernel param mutex to set the new module's param.
This fixes that by using per-module mutexes, so that each individual module
is protected against concurrent changes in its own kernel params, but is
not blocked by changes to other module params. All built-in modules
continue to use the built-in mutex, since they will always be loaded at
runtime and references (e.g. request_module(), crypto_has_alg()) to them
will never cause load-time param changing.
This also simplifies the interface used by modules to block sysfs access
to their params; while there are currently functions to block and unblock
sysfs param access which are split up by read and write and expect a single
kernel param to be passed, their actual operation is identical and applies
to all params, not just the one passed to them; they simply lock and unlock
the global param mutex. They are replaced with direct calls to
kernel_param_[un]lock(THIS_MODULE), which locks THIS_MODULE's param_lock, or
if the module is built-in, it locks the built-in mutex.
Suggested-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/arch/um/drivers/hostaudio_kern.c b/arch/um/drivers/hostaudio_kern.c
index 9b90fdc..f6b911c 100644
--- a/arch/um/drivers/hostaudio_kern.c
+++ b/arch/um/drivers/hostaudio_kern.c
@@ -185,9 +185,9 @@
int ret;
#ifdef DEBUG
- kparam_block_sysfs_write(dsp);
+ kernel_param_lock(THIS_MODULE);
printk(KERN_DEBUG "hostaudio: open called (host: %s)\n", dsp);
- kparam_unblock_sysfs_write(dsp);
+ kernel_param_unlock(THIS_MODULE);
#endif
state = kmalloc(sizeof(struct hostaudio_state), GFP_KERNEL);
@@ -199,11 +199,11 @@
if (file->f_mode & FMODE_WRITE)
w = 1;
- kparam_block_sysfs_write(dsp);
+ kernel_param_lock(THIS_MODULE);
mutex_lock(&hostaudio_mutex);
ret = os_open_file(dsp, of_set_rw(OPENFLAGS(), r, w), 0);
mutex_unlock(&hostaudio_mutex);
- kparam_unblock_sysfs_write(dsp);
+ kernel_param_unlock(THIS_MODULE);
if (ret < 0) {
kfree(state);
@@ -260,17 +260,17 @@
if (file->f_mode & FMODE_WRITE)
w = 1;
- kparam_block_sysfs_write(mixer);
+ kernel_param_lock(THIS_MODULE);
mutex_lock(&hostaudio_mutex);
ret = os_open_file(mixer, of_set_rw(OPENFLAGS(), r, w), 0);
mutex_unlock(&hostaudio_mutex);
- kparam_unblock_sysfs_write(mixer);
+ kernel_param_unlock(THIS_MODULE);
if (ret < 0) {
- kparam_block_sysfs_write(dsp);
+ kernel_param_lock(THIS_MODULE);
printk(KERN_ERR "hostaudio_open_mixdev failed to open '%s', "
"err = %d\n", dsp, -ret);
- kparam_unblock_sysfs_write(dsp);
+ kernel_param_unlock(THIS_MODULE);
kfree(state);
return ret;
}
@@ -326,10 +326,10 @@
static int __init hostaudio_init_module(void)
{
- __kernel_param_lock();
+ kernel_param_lock(THIS_MODULE);
printk(KERN_INFO "UML Audio Relay (host dsp = %s, host mixer = %s)\n",
dsp, mixer);
- __kernel_param_unlock();
+ kernel_param_unlock(THIS_MODULE);
module_data.dev_audio = register_sound_dsp(&hostaudio_fops, -1);
if (module_data.dev_audio < 0) {
diff --git a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
index 2bae502..83651ac 100644
--- a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
+++ b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
@@ -279,7 +279,7 @@
MODULE_FIRMWARE("myri10ge_rss_ethp_z8e.dat");
MODULE_FIRMWARE("myri10ge_rss_eth_z8e.dat");
-/* Careful: must be accessed under kparam_block_sysfs_write */
+/* Careful: must be accessed under kernel_param_lock() */
static char *myri10ge_fw_name = NULL;
module_param(myri10ge_fw_name, charp, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(myri10ge_fw_name, "Firmware image name");
@@ -3427,7 +3427,7 @@
}
}
- kparam_block_sysfs_write(myri10ge_fw_name);
+ kernel_param_lock(THIS_MODULE);
if (myri10ge_fw_name != NULL) {
char *fw_name = kstrdup(myri10ge_fw_name, GFP_KERNEL);
if (fw_name) {
@@ -3435,7 +3435,7 @@
set_fw_name(mgp, fw_name, true);
}
}
- kparam_unblock_sysfs_write(myri10ge_fw_name);
+ kernel_param_unlock(THIS_MODULE);
if (mgp->board_number < MYRI10GE_MAX_BOARDS &&
myri10ge_fw_names[mgp->board_number] != NULL &&
diff --git a/drivers/net/wireless/libertas_tf/if_usb.c b/drivers/net/wireless/libertas_tf/if_usb.c
index 1a20cee..799a2ef 100644
--- a/drivers/net/wireless/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/libertas_tf/if_usb.c
@@ -821,15 +821,15 @@
lbtf_deb_enter(LBTF_DEB_USB);
- kparam_block_sysfs_write(fw_name);
+ kernel_param_lock(THIS_MODULE);
ret = request_firmware(&cardp->fw, lbtf_fw_name, &cardp->udev->dev);
if (ret < 0) {
pr_err("request_firmware() failed with %#x\n", ret);
pr_err("firmware %s not found\n", lbtf_fw_name);
- kparam_unblock_sysfs_write(fw_name);
+ kernel_param_unlock(THIS_MODULE);
goto done;
}
- kparam_unblock_sysfs_write(fw_name);
+ kernel_param_unlock(THIS_MODULE);
if (check_fwfile_format(cardp->fw->data, cardp->fw->size))
goto release_fw;
diff --git a/drivers/usb/atm/ueagle-atm.c b/drivers/usb/atm/ueagle-atm.c
index 888998a..a2ae88d 100644
--- a/drivers/usb/atm/ueagle-atm.c
+++ b/drivers/usb/atm/ueagle-atm.c
@@ -1599,7 +1599,7 @@
char file_arr[] = "CMVxy.bin";
char *file;
- kparam_block_sysfs_write(cmv_file);
+ kernel_param_lock(THIS_MODULE);
/* set proper name corresponding modem version and line type */
if (cmv_file[sc->modem_index] == NULL) {
if (UEA_CHIP_VERSION(sc) == ADI930)
@@ -1618,7 +1618,7 @@
strlcat(cmv_name, file, UEA_FW_NAME_MAX);
if (ver == 2)
strlcat(cmv_name, ".v2", UEA_FW_NAME_MAX);
- kparam_unblock_sysfs_write(cmv_file);
+ kernel_param_unlock(THIS_MODULE);
}
static int request_cmvs_old(struct uea_softc *sc,
diff --git a/drivers/video/fbdev/vt8623fb.c b/drivers/video/fbdev/vt8623fb.c
index ea7f056..8bac309 100644
--- a/drivers/video/fbdev/vt8623fb.c
+++ b/drivers/video/fbdev/vt8623fb.c
@@ -754,9 +754,9 @@
/* Prepare startup mode */
- kparam_block_sysfs_write(mode_option);
+ kernel_param_lock(THIS_MODULE);
rc = fb_find_mode(&(info->var), info, mode_option, NULL, 0, NULL, 8);
- kparam_unblock_sysfs_write(mode_option);
+ kernel_param_unlock(THIS_MODULE);
if (! ((rc == 1) || (rc == 2))) {
rc = -EINVAL;
dev_err(info->device, "mode %s not found\n", mode_option);
diff --git a/include/linux/module.h b/include/linux/module.h
index 4c1b02e..6ba0e87 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -240,6 +240,7 @@
unsigned int num_syms;
/* Kernel parameters. */
+ struct mutex param_lock;
struct kernel_param *kp;
unsigned int num_kp;
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index ab50314..f1fdc50 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -67,6 +67,7 @@
struct kernel_param {
const char *name;
+ struct module *mod;
const struct kernel_param_ops *ops;
const u16 perm;
s8 level;
@@ -108,7 +109,7 @@
*
* @perm is 0 if the the variable is not to appear in sysfs, or 0444
* for world-readable, 0644 for root-writable, etc. Note that if it
- * is writable, you may need to use kparam_block_sysfs_write() around
+ * is writable, you may need to use kernel_param_lock() around
* accesses (esp. charp, which can be kfreed when it changes).
*
* The @type is simply pasted to refer to a param_ops_##type and a
@@ -216,12 +217,12 @@
parameters. */
#define __module_param_call(prefix, name, ops, arg, perm, level, flags) \
/* Default value instead of permissions? */ \
- static const char __param_str_##name[] = prefix #name; \
+ static const char __param_str_##name[] = prefix #name; \
static struct kernel_param __moduleparam_const __param_##name \
__used \
__attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
- = { __param_str_##name, ops, VERIFY_OCTAL_PERMISSIONS(perm), \
- level, flags, { arg } }
+ = { __param_str_##name, THIS_MODULE, ops, \
+ VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } }
/* Obsolete - use module_param_cb() */
#define module_param_call(name, set, get, arg, perm) \
@@ -238,58 +239,14 @@
return 0;
}
-/**
- * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
- * @name: the name of the parameter
- *
- * There's no point blocking write on a paramter that isn't writable via sysfs!
- */
-#define kparam_block_sysfs_write(name) \
- do { \
- BUG_ON(!(__param_##name.perm & 0222)); \
- __kernel_param_lock(); \
- } while (0)
-
-/**
- * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
- * @name: the name of the parameter
- */
-#define kparam_unblock_sysfs_write(name) \
- do { \
- BUG_ON(!(__param_##name.perm & 0222)); \
- __kernel_param_unlock(); \
- } while (0)
-
-/**
- * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
- * @name: the name of the parameter
- *
- * This also blocks sysfs writes.
- */
-#define kparam_block_sysfs_read(name) \
- do { \
- BUG_ON(!(__param_##name.perm & 0444)); \
- __kernel_param_lock(); \
- } while (0)
-
-/**
- * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
- * @name: the name of the parameter
- */
-#define kparam_unblock_sysfs_read(name) \
- do { \
- BUG_ON(!(__param_##name.perm & 0444)); \
- __kernel_param_unlock(); \
- } while (0)
-
#ifdef CONFIG_SYSFS
-extern void __kernel_param_lock(void);
-extern void __kernel_param_unlock(void);
+extern void kernel_param_lock(struct module *mod);
+extern void kernel_param_unlock(struct module *mod);
#else
-static inline void __kernel_param_lock(void)
+static inline void kernel_param_lock(struct module *mod)
{
}
-static inline void __kernel_param_unlock(void)
+static inline void kernel_param_unlock(struct module *mod)
{
}
#endif
diff --git a/kernel/module.c b/kernel/module.c
index 427b99f..8ec33ce 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3442,6 +3442,8 @@
if (err)
goto unlink_mod;
+ mutex_init(&mod->param_lock);
+
/* Now we've got everything in the final locations, we can
* find optional sections. */
err = find_module_sections(mod, info);
diff --git a/kernel/params.c b/kernel/params.c
index a8b09f6..8890d0b 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -25,15 +25,20 @@
#include <linux/slab.h>
#include <linux/ctype.h>
-/* Protects all parameters, and incidentally kmalloced_param list. */
+/* 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 : ¶m_lock)
+#define KPARAM_IS_LOCKED(mod) mutex_is_locked(KPARAM_MUTEX(mod))
+
/* This just allows us to keep track of which parameters are kmalloced. */
struct kmalloced_param {
struct list_head list;
char val[];
};
static LIST_HEAD(kmalloced_params);
+static DEFINE_SPINLOCK(kmalloced_params_lock);
static void *kmalloc_parameter(unsigned int size)
{
@@ -43,7 +48,10 @@
if (!p)
return NULL;
+ spin_lock(&kmalloced_params_lock);
list_add(&p->list, &kmalloced_params);
+ spin_unlock(&kmalloced_params_lock);
+
return p->val;
}
@@ -52,6 +60,7 @@
{
struct kmalloced_param *p;
+ spin_lock(&kmalloced_params_lock);
list_for_each_entry(p, &kmalloced_params, list) {
if (p->val == param) {
list_del(&p->list);
@@ -59,6 +68,7 @@
break;
}
}
+ spin_unlock(&kmalloced_params_lock);
}
static char dash2underscore(char c)
@@ -118,10 +128,10 @@
return -EINVAL;
pr_debug("handling %s with %p\n", param,
params[i].ops->set);
- mutex_lock(¶m_lock);
+ kernel_param_lock(params[i].mod);
param_check_unsafe(¶ms[i]);
err = params[i].ops->set(val, ¶ms[i]);
- mutex_unlock(¶m_lock);
+ kernel_param_unlock(params[i].mod);
return err;
}
}
@@ -417,7 +427,8 @@
EXPORT_SYMBOL(param_ops_bint);
/* We break the rule and mangle the string. */
-static int param_array(const char *name,
+static int param_array(struct module *mod,
+ const char *name,
const char *val,
unsigned int min, unsigned int max,
void *elem, int elemsize,
@@ -448,7 +459,7 @@
/* nul-terminate and parse */
save = val[len];
((char *)val)[len] = '\0';
- BUG_ON(!mutex_is_locked(¶m_lock));
+ BUG_ON(!KPARAM_IS_LOCKED(mod));
ret = set(val, &kp);
if (ret != 0)
@@ -470,7 +481,7 @@
const struct kparam_array *arr = kp->arr;
unsigned int temp_num;
- return param_array(kp->name, val, 1, arr->max, arr->elem,
+ return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
arr->elemsize, arr->ops->set, kp->level,
arr->num ?: &temp_num);
}
@@ -485,7 +496,7 @@
if (i)
buffer[off++] = ',';
p.arg = arr->elem + arr->elemsize * i;
- BUG_ON(!mutex_is_locked(¶m_lock));
+ BUG_ON(!KPARAM_IS_LOCKED(p.mod));
ret = arr->ops->get(buffer + off, &p);
if (ret < 0)
return ret;
@@ -568,9 +579,9 @@
if (!attribute->param->ops->get)
return -EPERM;
- mutex_lock(¶m_lock);
+ kernel_param_lock(mk->mod);
count = attribute->param->ops->get(buf, attribute->param);
- mutex_unlock(¶m_lock);
+ kernel_param_unlock(mk->mod);
if (count > 0) {
strcat(buf, "\n");
++count;
@@ -580,7 +591,7 @@
/* sysfs always hands a nul-terminated string in buf. We rely on that. */
static ssize_t param_attr_store(struct module_attribute *mattr,
- struct module_kobject *km,
+ struct module_kobject *mk,
const char *buf, size_t len)
{
int err;
@@ -589,10 +600,10 @@
if (!attribute->param->ops->set)
return -EPERM;
- mutex_lock(¶m_lock);
+ kernel_param_lock(mk->mod);
param_check_unsafe(attribute->param);
err = attribute->param->ops->set(buf, attribute->param);
- mutex_unlock(¶m_lock);
+ kernel_param_unlock(mk->mod);
if (!err)
return len;
return err;
@@ -605,18 +616,19 @@
#define __modinit __init
#endif
-#ifdef CONFIG_SYSFS
-void __kernel_param_lock(void)
+void kernel_param_lock(struct module *mod)
{
- mutex_lock(¶m_lock);
+ mutex_lock(KPARAM_MUTEX(mod));
}
-EXPORT_SYMBOL(__kernel_param_lock);
-void __kernel_param_unlock(void)
+void kernel_param_unlock(struct module *mod)
{
- mutex_unlock(¶m_lock);
+ mutex_unlock(KPARAM_MUTEX(mod));
}
-EXPORT_SYMBOL(__kernel_param_unlock);
+
+#ifdef CONFIG_SYSFS
+EXPORT_SYMBOL(kernel_param_lock);
+EXPORT_SYMBOL(kernel_param_unlock);
/*
* add_sysfs_param - add a parameter to sysfs
diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index d53355b..8544e2e 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -103,7 +103,7 @@
const struct rate_control_ops *ops;
const char *alg_name;
- kparam_block_sysfs_write(ieee80211_default_rc_algo);
+ kernel_param_lock(THIS_MODULE);
if (!name)
alg_name = ieee80211_default_rc_algo;
else
@@ -117,7 +117,7 @@
/* try built-in one if specific alg requested but not found */
if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
- kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
+ kernel_param_unlock(THIS_MODULE);
return ops;
}