From 2e9fb9953df91ef6310da22182ca8f4496907502 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:10 -0600 Subject: params: don't hand NULL values to param.set callbacks. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit An audit by Dongdong Deng revealed that most driver-author-written param calls don't handle val == NULL (which happens when parameters are specified with no =, eg "foo" instead of "foo=1"). The only real case to use this is boolean, so handle it specially for that case and remove a source of bugs for everyone else. Signed-off-by: Rusty Russell Cc: Dongdong Deng Cc: Américo Wang --- kernel/params.c | 20 +++----------------- 1 file changed, 3 insertions(+), 17 deletions(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index 0b30ecd53a52..3c4a9f1b095e 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -58,6 +58,9 @@ static int parse_one(char *param, /* Find parameter */ for (i = 0; i < num_params; i++) { if (parameq(param, params[i].name)) { + /* Noone handled NULL, so do it here. */ + if (!val && params[i].set != param_set_bool) + return -EINVAL; DEBUGP("They are equal! Calling %p\n", params[i].set); return params[i].set(val, ¶ms[i]); @@ -181,7 +184,6 @@ int parse_args(const char *name, tmptype l; \ int ret; \ \ - if (!val) return -EINVAL; \ ret = strtolfn(val, 0, &l); \ if (ret == -EINVAL || ((type)l != l)) \ return -EINVAL; \ @@ -203,12 +205,6 @@ STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, strict_strtoul); int param_set_charp(const char *val, struct kernel_param *kp) { - if (!val) { - printk(KERN_ERR "%s: string parameter expected\n", - kp->name); - return -EINVAL; - } - if (strlen(val) > 1024) { printk(KERN_ERR "%s: string parameter too long\n", kp->name); @@ -309,12 +305,6 @@ static int param_array(const char *name, kp.arg = elem; kp.flags = flags; - /* No equals sign? */ - if (!val) { - printk(KERN_ERR "%s: expects arguments\n", name); - return -EINVAL; - } - *num = 0; /* We expect a comma-separated list of values. */ do { @@ -381,10 +371,6 @@ int param_set_copystring(const char *val, struct kernel_param *kp) { const struct kparam_string *kps = kp->str; - if (!val) { - printk(KERN_ERR "%s: missing param set value\n", kp->name); - return -EINVAL; - } if (strlen(val)+1 > kps->maxlen) { printk(KERN_ERR "%s: string doesn't fit in %u chars.\n", kp->name, kps->maxlen-1); -- cgit v1.2.2 From a14fe249a8f74269c9e636bcbaa78f5bdb354ce3 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:11 -0600 Subject: param: move the EXPORT_SYMBOL to after the definitions. This is modern style, and good to do before we start changing things. Signed-off-by: Rusty Russell Reviewed-by: Takashi Iwai Tested-by: Phil Carmody --- kernel/params.c | 39 +++++++++++++-------------------------- 1 file changed, 13 insertions(+), 26 deletions(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index 3c4a9f1b095e..3e78fdb445e7 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -193,7 +193,9 @@ int parse_args(const char *name, int param_get_##name(char *buffer, struct kernel_param *kp) \ { \ return sprintf(buffer, format, *((type *)kp->arg)); \ - } + } \ + EXPORT_SYMBOL(param_set_##name); \ + EXPORT_SYMBOL(param_get_##name) STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, strict_strtoul); STANDARD_PARAM_DEF(short, short, "%hi", long, strict_strtol); @@ -222,11 +224,13 @@ int param_set_charp(const char *val, struct kernel_param *kp) return 0; } +EXPORT_SYMBOL(param_set_charp); int param_get_charp(char *buffer, struct kernel_param *kp) { return sprintf(buffer, "%s", *((char **)kp->arg)); } +EXPORT_SYMBOL(param_get_charp); /* Actually could be a bool or an int, for historical reasons. */ int param_set_bool(const char *val, struct kernel_param *kp) @@ -254,6 +258,7 @@ int param_set_bool(const char *val, struct kernel_param *kp) *(int *)kp->arg = v; return 0; } +EXPORT_SYMBOL(param_set_bool); int param_get_bool(char *buffer, struct kernel_param *kp) { @@ -266,6 +271,7 @@ int param_get_bool(char *buffer, struct kernel_param *kp) /* Y and N chosen as being relatively non-coder friendly */ return sprintf(buffer, "%c", val ? 'Y' : 'N'); } +EXPORT_SYMBOL(param_get_bool); /* This one must be bool. */ int param_set_invbool(const char *val, struct kernel_param *kp) @@ -281,11 +287,13 @@ int param_set_invbool(const char *val, struct kernel_param *kp) *(bool *)kp->arg = !boolval; return ret; } +EXPORT_SYMBOL(param_set_invbool); int param_get_invbool(char *buffer, struct kernel_param *kp) { return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y'); } +EXPORT_SYMBOL(param_get_invbool); /* We break the rule and mangle the string. */ static int param_array(const char *name, @@ -346,6 +354,7 @@ int param_array_set(const char *val, struct kernel_param *kp) arr->elemsize, arr->set, kp->flags, arr->num ?: &temp_num); } +EXPORT_SYMBOL(param_array_set); int param_array_get(char *buffer, struct kernel_param *kp) { @@ -366,6 +375,7 @@ int param_array_get(char *buffer, struct kernel_param *kp) buffer[off] = '\0'; return off; } +EXPORT_SYMBOL(param_array_get); int param_set_copystring(const char *val, struct kernel_param *kp) { @@ -379,12 +389,14 @@ int param_set_copystring(const char *val, struct kernel_param *kp) strcpy(kps->string, val); return 0; } +EXPORT_SYMBOL(param_set_copystring); int param_get_string(char *buffer, struct kernel_param *kp) { const struct kparam_string *kps = kp->str; return strlcpy(buffer, kps->string, kps->maxlen); } +EXPORT_SYMBOL(param_get_string); /* sysfs output in /sys/modules/XYZ/parameters/ */ #define to_module_attr(n) container_of(n, struct module_attribute, attr) @@ -754,28 +766,3 @@ static int __init param_sysfs_init(void) subsys_initcall(param_sysfs_init); #endif /* CONFIG_SYSFS */ - -EXPORT_SYMBOL(param_set_byte); -EXPORT_SYMBOL(param_get_byte); -EXPORT_SYMBOL(param_set_short); -EXPORT_SYMBOL(param_get_short); -EXPORT_SYMBOL(param_set_ushort); -EXPORT_SYMBOL(param_get_ushort); -EXPORT_SYMBOL(param_set_int); -EXPORT_SYMBOL(param_get_int); -EXPORT_SYMBOL(param_set_uint); -EXPORT_SYMBOL(param_get_uint); -EXPORT_SYMBOL(param_set_long); -EXPORT_SYMBOL(param_get_long); -EXPORT_SYMBOL(param_set_ulong); -EXPORT_SYMBOL(param_get_ulong); -EXPORT_SYMBOL(param_set_charp); -EXPORT_SYMBOL(param_get_charp); -EXPORT_SYMBOL(param_set_bool); -EXPORT_SYMBOL(param_get_bool); -EXPORT_SYMBOL(param_set_invbool); -EXPORT_SYMBOL(param_get_invbool); -EXPORT_SYMBOL(param_array_set); -EXPORT_SYMBOL(param_array_get); -EXPORT_SYMBOL(param_set_copystring); -EXPORT_SYMBOL(param_get_string); -- cgit v1.2.2 From 9bbb9e5a33109b2832e2e63dcc7a132924ab374b Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:12 -0600 Subject: param: use ops in struct kernel_param, rather than get and set fns directly This is more kernel-ish, saves some space, and also allows us to expand the ops without breaking all the callers who are happy for the new members to be NULL. The few places which defined their own param types are changed to the new scheme (more which crept in recently fixed in following patches). Since we're touching them anyway, we change get() and set() to take a const struct kernel_param (which they really are). This causes some harmless warnings until we fix them (in following patches). To reduce churn, module_param_call creates the ops struct so the callers don't have to change (and casts the functions to reduce warnings). The modern version which takes an ops struct is called module_param_cb. Signed-off-by: Rusty Russell Reviewed-by: Takashi Iwai Tested-by: Phil Carmody Cc: "David S. Miller" Cc: Ville Syrjala Cc: Dmitry Torokhov Cc: Alessandro Rubini Cc: Michal Januszewski Cc: Trond Myklebust Cc: "J. Bruce Fields" Cc: Neil Brown Cc: linux-kernel@vger.kernel.org Cc: linux-input@vger.kernel.org Cc: linux-fbdev-devel@lists.sourceforge.net Cc: linux-nfs@vger.kernel.org Cc: netdev@vger.kernel.org --- kernel/params.c | 90 +++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 62 insertions(+), 28 deletions(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index 3e78fdb445e7..a550698ae02d 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -59,11 +59,11 @@ static int parse_one(char *param, for (i = 0; i < num_params; i++) { if (parameq(param, params[i].name)) { /* Noone handled NULL, so do it here. */ - if (!val && params[i].set != param_set_bool) + if (!val && params[i].ops->set != param_set_bool) return -EINVAL; DEBUGP("They are equal! Calling %p\n", - params[i].set); - return params[i].set(val, ¶ms[i]); + params[i].ops->set); + return params[i].ops->set(val, ¶ms[i]); } } @@ -179,7 +179,7 @@ int parse_args(const char *name, /* Lazy bastard, eh? */ #define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn) \ - int param_set_##name(const char *val, struct kernel_param *kp) \ + int param_set_##name(const char *val, const struct kernel_param *kp) \ { \ tmptype l; \ int ret; \ @@ -190,12 +190,18 @@ int parse_args(const char *name, *((type *)kp->arg) = l; \ return 0; \ } \ - int param_get_##name(char *buffer, struct kernel_param *kp) \ + int param_get_##name(char *buffer, const struct kernel_param *kp) \ { \ return sprintf(buffer, format, *((type *)kp->arg)); \ } \ + struct kernel_param_ops param_ops_##name = { \ + .set = param_set_##name, \ + .get = param_get_##name, \ + }; \ EXPORT_SYMBOL(param_set_##name); \ - EXPORT_SYMBOL(param_get_##name) + EXPORT_SYMBOL(param_get_##name); \ + EXPORT_SYMBOL(param_ops_##name) + STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, strict_strtoul); STANDARD_PARAM_DEF(short, short, "%hi", long, strict_strtol); @@ -205,7 +211,7 @@ STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, strict_strtoul); STANDARD_PARAM_DEF(long, long, "%li", long, strict_strtol); STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, strict_strtoul); -int param_set_charp(const char *val, struct kernel_param *kp) +int param_set_charp(const char *val, const struct kernel_param *kp) { if (strlen(val) > 1024) { printk(KERN_ERR "%s: string parameter too long\n", @@ -226,14 +232,20 @@ int param_set_charp(const char *val, struct kernel_param *kp) } EXPORT_SYMBOL(param_set_charp); -int param_get_charp(char *buffer, struct kernel_param *kp) +int param_get_charp(char *buffer, const struct kernel_param *kp) { return sprintf(buffer, "%s", *((char **)kp->arg)); } EXPORT_SYMBOL(param_get_charp); +struct kernel_param_ops param_ops_charp = { + .set = param_set_charp, + .get = param_get_charp, +}; +EXPORT_SYMBOL(param_ops_charp); + /* Actually could be a bool or an int, for historical reasons. */ -int param_set_bool(const char *val, struct kernel_param *kp) +int param_set_bool(const char *val, const struct kernel_param *kp) { bool v; @@ -260,7 +272,7 @@ int param_set_bool(const char *val, struct kernel_param *kp) } EXPORT_SYMBOL(param_set_bool); -int param_get_bool(char *buffer, struct kernel_param *kp) +int param_get_bool(char *buffer, const struct kernel_param *kp) { bool val; if (kp->flags & KPARAM_ISBOOL) @@ -273,8 +285,14 @@ int param_get_bool(char *buffer, struct kernel_param *kp) } EXPORT_SYMBOL(param_get_bool); +struct kernel_param_ops param_ops_bool = { + .set = param_set_bool, + .get = param_get_bool, +}; +EXPORT_SYMBOL(param_ops_bool); + /* This one must be bool. */ -int param_set_invbool(const char *val, struct kernel_param *kp) +int param_set_invbool(const char *val, const struct kernel_param *kp) { int ret; bool boolval; @@ -289,18 +307,24 @@ int param_set_invbool(const char *val, struct kernel_param *kp) } EXPORT_SYMBOL(param_set_invbool); -int param_get_invbool(char *buffer, struct kernel_param *kp) +int param_get_invbool(char *buffer, const struct kernel_param *kp) { return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y'); } EXPORT_SYMBOL(param_get_invbool); +struct kernel_param_ops param_ops_invbool = { + .set = param_set_invbool, + .get = param_get_invbool, +}; +EXPORT_SYMBOL(param_ops_invbool); + /* We break the rule and mangle the string. */ static int param_array(const char *name, const char *val, unsigned int min, unsigned int max, void *elem, int elemsize, - int (*set)(const char *, struct kernel_param *kp), + int (*set)(const char *, const struct kernel_param *kp), u16 flags, unsigned int *num) { @@ -345,18 +369,17 @@ static int param_array(const char *name, return 0; } -int param_array_set(const char *val, struct kernel_param *kp) +static int param_array_set(const char *val, const struct kernel_param *kp) { const struct kparam_array *arr = kp->arr; unsigned int temp_num; return param_array(kp->name, val, 1, arr->max, arr->elem, - arr->elemsize, arr->set, kp->flags, + arr->elemsize, arr->ops->set, kp->flags, arr->num ?: &temp_num); } -EXPORT_SYMBOL(param_array_set); -int param_array_get(char *buffer, struct kernel_param *kp) +static int param_array_get(char *buffer, const struct kernel_param *kp) { int i, off, ret; const struct kparam_array *arr = kp->arr; @@ -367,7 +390,7 @@ int param_array_get(char *buffer, struct kernel_param *kp) if (i) buffer[off++] = ','; p.arg = arr->elem + arr->elemsize * i; - ret = arr->get(buffer + off, &p); + ret = arr->ops->get(buffer + off, &p); if (ret < 0) return ret; off += ret; @@ -375,9 +398,14 @@ int param_array_get(char *buffer, struct kernel_param *kp) buffer[off] = '\0'; return off; } -EXPORT_SYMBOL(param_array_get); -int param_set_copystring(const char *val, struct kernel_param *kp) +struct kernel_param_ops param_array_ops = { + .set = param_array_set, + .get = param_array_get, +}; +EXPORT_SYMBOL(param_array_ops); + +int param_set_copystring(const char *val, const struct kernel_param *kp) { const struct kparam_string *kps = kp->str; @@ -391,13 +419,19 @@ int param_set_copystring(const char *val, struct kernel_param *kp) } EXPORT_SYMBOL(param_set_copystring); -int param_get_string(char *buffer, struct kernel_param *kp) +int param_get_string(char *buffer, const struct kernel_param *kp) { const struct kparam_string *kps = kp->str; return strlcpy(buffer, kps->string, kps->maxlen); } EXPORT_SYMBOL(param_get_string); +struct kernel_param_ops param_ops_string = { + .set = param_set_copystring, + .get = param_get_string, +}; +EXPORT_SYMBOL(param_ops_string); + /* sysfs output in /sys/modules/XYZ/parameters/ */ #define to_module_attr(n) container_of(n, struct module_attribute, attr) #define to_module_kobject(n) container_of(n, struct module_kobject, kobj) @@ -407,7 +441,7 @@ extern struct kernel_param __start___param[], __stop___param[]; struct param_attribute { struct module_attribute mattr; - struct kernel_param *param; + const struct kernel_param *param; }; struct module_param_attrs @@ -426,10 +460,10 @@ static ssize_t param_attr_show(struct module_attribute *mattr, int count; struct param_attribute *attribute = to_param_attr(mattr); - if (!attribute->param->get) + if (!attribute->param->ops->get) return -EPERM; - count = attribute->param->get(buf, attribute->param); + count = attribute->param->ops->get(buf, attribute->param); if (count > 0) { strcat(buf, "\n"); ++count; @@ -445,10 +479,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr, int err; struct param_attribute *attribute = to_param_attr(mattr); - if (!attribute->param->set) + if (!attribute->param->ops->set) return -EPERM; - err = attribute->param->set(buf, attribute->param); + err = attribute->param->ops->set(buf, attribute->param); if (!err) return len; return err; @@ -473,7 +507,7 @@ static ssize_t param_attr_store(struct module_attribute *mattr, * if there's an error. */ static __modinit int add_sysfs_param(struct module_kobject *mk, - struct kernel_param *kp, + const struct kernel_param *kp, const char *name) { struct module_param_attrs *new; @@ -555,7 +589,7 @@ static void free_module_param_attrs(struct module_kobject *mk) * /sys/module/[mod->name]/parameters/ */ int module_param_sysfs_setup(struct module *mod, - struct kernel_param *kparam, + const struct kernel_param *kparam, unsigned int num_params) { int i, err; -- cgit v1.2.2 From e6df34a4429b77fdffb6e05adf263468a3dcda33 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:17 -0600 Subject: param: add a free hook to kernel_param_ops. This allows us to generalize the KPARAM_KMALLOCED flag, by calling a function on every parameter when a module is unloaded. Signed-off-by: Rusty Russell Reviewed-by: Takashi Iwai Tested-by: Phil Carmody --- kernel/params.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index a550698ae02d..458a09b886c4 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -399,9 +399,20 @@ static int param_array_get(char *buffer, const struct kernel_param *kp) return off; } +static void param_array_free(void *arg) +{ + unsigned int i; + const struct kparam_array *arr = arg; + + if (arr->ops->free) + for (i = 0; i < (arr->num ? *arr->num : arr->max); i++) + arr->ops->free(arr->elem + arr->elemsize * i); +} + struct kernel_param_ops param_array_ops = { .set = param_array_set, .get = param_array_get, + .free = param_array_free, }; EXPORT_SYMBOL(param_array_ops); @@ -634,7 +645,11 @@ void module_param_sysfs_remove(struct module *mod) void destroy_params(const struct kernel_param *params, unsigned num) { - /* FIXME: This should free kmalloced charp parameters. It doesn't. */ + unsigned int i; + + for (i = 0; i < num; i++) + if (params[i].ops->free) + params[i].ops->free(params[i].arg); } static void __init kernel_add_sysfs_param(const char *name, -- cgit v1.2.2 From a1054322afc8120ea5a50bc84e5beeda54571862 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:18 -0600 Subject: param: use free hook for charp (fix leak of charp parameters) Instead of using a "I kmalloced this" flag, we keep track of the kmalloced strings and use that list to check if we need to kfree (in practice, the list is very short). This means that kparams can be const again, and plugs a leak. This is important for drivers/usb/gadget/nokia.c which gets modprobe/rmmod'ed frequently on the N9000. Signed-off-by: Rusty Russell Reviewed-by: Takashi Iwai Cc: Artem Bityutskiy Tested-by: Phil Carmody --- kernel/params.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 50 insertions(+), 2 deletions(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index 458a09b886c4..ef60db14fae0 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -31,6 +31,45 @@ #define DEBUGP(fmt, a...) #endif +/* This just allows us to keep track of which parameters are kmalloced. */ +struct kmalloced_param { + struct list_head list; + char val[]; +}; +static DEFINE_MUTEX(param_lock); +static LIST_HEAD(kmalloced_params); + +static void *kmalloc_parameter(unsigned int size) +{ + struct kmalloced_param *p; + + p = kmalloc(sizeof(*p) + size, GFP_KERNEL); + if (!p) + return NULL; + + mutex_lock(¶m_lock); + list_add(&p->list, &kmalloced_params); + mutex_unlock(¶m_lock); + + return p->val; +} + +/* Does nothing if parameter wasn't kmalloced above. */ +static void maybe_kfree_parameter(void *param) +{ + struct kmalloced_param *p; + + mutex_lock(¶m_lock); + list_for_each_entry(p, &kmalloced_params, list) { + if (p->val == param) { + list_del(&p->list); + kfree(p); + break; + } + } + mutex_unlock(¶m_lock); +} + static inline char dash2underscore(char c) { if (c == '-') @@ -219,12 +258,15 @@ int param_set_charp(const char *val, const struct kernel_param *kp) return -ENOSPC; } - /* This is a hack. We can't need to strdup in early boot, and we + maybe_kfree_parameter(*(char **)kp->arg); + + /* This is a hack. We can't kmalloc in early boot, and we * don't need to; this mangled commandline is preserved. */ if (slab_is_available()) { - *(char **)kp->arg = kstrdup(val, GFP_KERNEL); + *(char **)kp->arg = kmalloc_parameter(strlen(val)+1); if (!*(char **)kp->arg) return -ENOMEM; + strcpy(*(char **)kp->arg, val); } else *(const char **)kp->arg = val; @@ -238,9 +280,15 @@ int param_get_charp(char *buffer, const struct kernel_param *kp) } EXPORT_SYMBOL(param_get_charp); +static void param_free_charp(void *arg) +{ + maybe_kfree_parameter(*((char **)arg)); +} + struct kernel_param_ops param_ops_charp = { .set = param_set_charp, .get = param_get_charp, + .free = param_free_charp, }; EXPORT_SYMBOL(param_ops_charp); -- cgit v1.2.2 From 914dcaa84c53f2c3efa6016efcae13fd92a8a17c Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:18 -0600 Subject: param: make param sections const. Since this section can be read-only (they're in .rodata), they should always have been const. Minor flow-through various functions. Signed-off-by: Rusty Russell Tested-by: Phil Carmody --- kernel/params.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index ef60db14fae0..a3eeeefc9472 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -88,7 +88,7 @@ static inline int parameq(const char *input, const char *paramname) static int parse_one(char *param, char *val, - struct kernel_param *params, + const struct kernel_param *params, unsigned num_params, int (*handle_unknown)(char *param, char *val)) { @@ -170,7 +170,7 @@ static char *next_arg(char *args, char **param, char **val) /* Args looks like "foo=bar,bar2 baz=fuz wiz". */ int parse_args(const char *name, char *args, - struct kernel_param *params, + const struct kernel_param *params, unsigned num, int (*unknown)(char *param, char *val)) { -- cgit v1.2.2 From 907b29eb41aa604477a655bff7345731da94514d Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 11 Aug 2010 23:04:19 -0600 Subject: param: locking for kernel parameters There may be cases (most obviously, sysfs-writable charp parameters) where a module needs to prevent sysfs access to parameters. Rather than express this in terms of a big lock, the functions are expressed in terms of what they protect against. This is clearer, esp. if the implementation changes to a module-level or even param-level lock. Signed-off-by: Rusty Russell Reviewed-by: Takashi Iwai Tested-by: Phil Carmody --- kernel/params.c | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-) (limited to 'kernel/params.c') diff --git a/kernel/params.c b/kernel/params.c index a3eeeefc9472..08107d181758 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -31,12 +31,14 @@ #define DEBUGP(fmt, a...) #endif +/* Protects all parameters, and incidentally kmalloced_param list. */ +static DEFINE_MUTEX(param_lock); + /* This just allows us to keep track of which parameters are kmalloced. */ struct kmalloced_param { struct list_head list; char val[]; }; -static DEFINE_MUTEX(param_lock); static LIST_HEAD(kmalloced_params); static void *kmalloc_parameter(unsigned int size) @@ -47,10 +49,7 @@ static void *kmalloc_parameter(unsigned int size) if (!p) return NULL; - mutex_lock(¶m_lock); list_add(&p->list, &kmalloced_params); - mutex_unlock(¶m_lock); - return p->val; } @@ -59,7 +58,6 @@ static void maybe_kfree_parameter(void *param) { struct kmalloced_param *p; - mutex_lock(¶m_lock); list_for_each_entry(p, &kmalloced_params, list) { if (p->val == param) { list_del(&p->list); @@ -67,7 +65,6 @@ static void maybe_kfree_parameter(void *param) break; } } - mutex_unlock(¶m_lock); } static inline char dash2underscore(char c) @@ -93,6 +90,7 @@ static int parse_one(char *param, int (*handle_unknown)(char *param, char *val)) { unsigned int i; + int err; /* Find parameter */ for (i = 0; i < num_params; i++) { @@ -102,7 +100,10 @@ static int parse_one(char *param, return -EINVAL; DEBUGP("They are equal! Calling %p\n", params[i].ops->set); - return params[i].ops->set(val, ¶ms[i]); + mutex_lock(¶m_lock); + err = params[i].ops->set(val, ¶ms[i]); + mutex_unlock(¶m_lock); + return err; } } @@ -400,6 +401,7 @@ static int param_array(const char *name, /* nul-terminate and parse */ save = val[len]; ((char *)val)[len] = '\0'; + BUG_ON(!mutex_is_locked(¶m_lock)); ret = set(val, &kp); if (ret != 0) @@ -438,6 +440,7 @@ 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(!mutex_is_locked(¶m_lock)); ret = arr->ops->get(buffer + off, &p); if (ret < 0) return ret; @@ -522,7 +525,9 @@ static ssize_t param_attr_show(struct module_attribute *mattr, if (!attribute->param->ops->get) return -EPERM; + mutex_lock(¶m_lock); count = attribute->param->ops->get(buf, attribute->param); + mutex_unlock(¶m_lock); if (count > 0) { strcat(buf, "\n"); ++count; @@ -541,7 +546,9 @@ static ssize_t param_attr_store(struct module_attribute *mattr, if (!attribute->param->ops->set) return -EPERM; + mutex_lock(¶m_lock); err = attribute->param->ops->set(buf, attribute->param); + mutex_unlock(¶m_lock); if (!err) return len; return err; @@ -555,6 +562,18 @@ static ssize_t param_attr_store(struct module_attribute *mattr, #endif #ifdef CONFIG_SYSFS +void __kernel_param_lock(void) +{ + mutex_lock(¶m_lock); +} +EXPORT_SYMBOL(__kernel_param_lock); + +void __kernel_param_unlock(void) +{ + mutex_unlock(¶m_lock); +} +EXPORT_SYMBOL(__kernel_param_unlock); + /* * add_sysfs_param - add a parameter to sysfs * @mk: struct module_kobject -- cgit v1.2.2