These are the remaining 2 patches that came from the original ftrace/livepatch
module notifier patchset found here: https://lkml.org/lkml/2016/2/8/1180
Basically, the patchset does a bit of module.c cleanup (patch 1) in
preparation for the klp_module_{coming,going} calls (patch 2). We decided
to stop relying on the module notifier callchain in favor of hard-coding
the appropriate livepatch function calls that handle coming and going
modules. Hard-coding these calls will guarantee that ftrace and livepatch
exit/initialization routines are called in the correct order without
relying on module notifiers.
The patches should be nearly exactly the same as those from the previous
discussion, except in patch 2 I've added back the #if IS_ENABLED(CONFIG_LIVEPATCH)
guard in livepatch.h.
Patches based on linux-next.
Previous discussion (v4) found here: https://lkml.org/lkml/2016/2/8/1180
v2:
- we don't need to change mod->state to GOING when cleaning up during
failed module load
- modify mod->state check to allow klp_module_going() to be called in
both COMING and GOING states
Jessica Yu (2):
modules: split part of complete_formation() into prepare_coming_module()
livepatch/module: remove livepatch module notifier
include/linux/livepatch.h | 13 ++++
kernel/livepatch/core.c | 147 ++++++++++++++++++++++------------------------
kernel/module.c | 36 +++++++++---
3 files changed, 112 insertions(+), 84 deletions(-)
--
2.4.3
Put all actions in complete_formation() that are performed after
module->state is set to MODULE_STATE_COMING into a separate function
prepare_coming_module(). This split prepares for the removal of the
livepatch module notifiers in favor of hard-coding function calls to
klp_module_{coming,going} in the module loader.
The complete_formation -> prepare_coming_module split will also make error
handling easier since we can jump to the appropriate error label to do any
module GOING cleanup after all the COMING-actions have completed.
Signed-off-by: Jessica Yu <[email protected]>
Reviewed-by: Josh Poimboeuf <[email protected]>
Acked-by: Rusty Russell <[email protected]>
---
kernel/module.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 87cfeb2..1981ae0 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3312,6 +3312,14 @@ out_unlocked:
return err;
}
+static int prepare_coming_module(struct module *mod)
+{
+ ftrace_module_enable(mod);
+ blocking_notifier_call_chain(&module_notify_list,
+ MODULE_STATE_COMING, mod);
+ return 0;
+}
+
static int complete_formation(struct module *mod, struct load_info *info)
{
int err;
@@ -3335,9 +3343,6 @@ static int complete_formation(struct module *mod, struct load_info *info)
mod->state = MODULE_STATE_COMING;
mutex_unlock(&module_mutex);
- ftrace_module_enable(mod);
- blocking_notifier_call_chain(&module_notify_list,
- MODULE_STATE_COMING, mod);
return 0;
out:
@@ -3459,13 +3464,17 @@ static int load_module(struct load_info *info, const char __user *uargs,
if (err)
goto ddebug_cleanup;
+ err = prepare_coming_module(mod);
+ if (err)
+ goto bug_cleanup;
+
/* Module is ready to execute: parsing args may do that. */
after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
-32768, 32767, mod,
unknown_module_param_cb);
if (IS_ERR(after_dashes)) {
err = PTR_ERR(after_dashes);
- goto bug_cleanup;
+ goto coming_cleanup;
} else if (after_dashes) {
pr_warn("%s: parameters '%s' after `--' ignored\n",
mod->name, after_dashes);
@@ -3474,7 +3483,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
/* Link in to syfs. */
err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp);
if (err < 0)
- goto bug_cleanup;
+ goto coming_cleanup;
/* Get rid of temporary copy. */
free_copy(info);
@@ -3484,15 +3493,16 @@ static int load_module(struct load_info *info, const char __user *uargs,
return do_init_module(mod);
+ coming_cleanup:
+ blocking_notifier_call_chain(&module_notify_list,
+ MODULE_STATE_GOING, mod);
+
bug_cleanup:
/* module_bug_cleanup needs module_mutex protection */
mutex_lock(&module_mutex);
module_bug_cleanup(mod);
mutex_unlock(&module_mutex);
- blocking_notifier_call_chain(&module_notify_list,
- MODULE_STATE_GOING, mod);
-
/* we can't deallocate the module until we clear memory protection */
module_disable_ro(mod);
module_disable_nx(mod);
--
2.4.3
Remove the livepatch module notifier in favor of directly enabling and
disabling patches to modules in the module loader. Hard-coding the
function calls ensures that ftrace_module_enable() is run before
klp_module_coming() during module load, and that klp_module_going() is
run before ftrace_release_mod() during module unload. This way, ftrace
and livepatch code is run in the correct order during the module
load/unload sequence without dependence on the module notifier call chain.
Signed-off-by: Jessica Yu <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
Acked-by: Rusty Russell <[email protected]>
---
include/linux/livepatch.h | 13 ++++
kernel/livepatch/core.c | 147 ++++++++++++++++++++++------------------------
kernel/module.c | 10 ++++
3 files changed, 94 insertions(+), 76 deletions(-)
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index c056797..bd830d5 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -24,6 +24,8 @@
#include <linux/module.h>
#include <linux/ftrace.h>
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+
#include <asm/livepatch.h>
enum klp_state {
@@ -132,4 +134,15 @@ int klp_unregister_patch(struct klp_patch *);
int klp_enable_patch(struct klp_patch *);
int klp_disable_patch(struct klp_patch *);
+/* Called from the module loader during module coming/going states */
+int klp_module_coming(struct module *mod);
+void klp_module_going(struct module *mod);
+
+#else /* !CONFIG_LIVEPATCH */
+
+static inline int klp_module_coming(struct module *mod) { return 0; }
+static inline void klp_module_going(struct module *mod) { }
+
+#endif /* CONFIG_LIVEPATCH */
+
#endif /* _LINUX_LIVEPATCH_H_ */
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 780f00c..4fafbae 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -99,12 +99,12 @@ static void klp_find_object_module(struct klp_object *obj)
/*
* We do not want to block removal of patched modules and therefore
* we do not take a reference here. The patches are removed by
- * a going module handler instead.
+ * klp_module_going() instead.
*/
mod = find_module(obj->name);
/*
- * Do not mess work of the module coming and going notifiers.
- * Note that the patch might still be needed before the going handler
+ * Do not mess work of klp_module_coming() and klp_module_going().
+ * Note that the patch might still be needed before klp_module_going()
* is called. Module functions can be called even in the GOING state
* until mod->exit() finishes. This is especially important for
* patches that modify semantic of the functions.
@@ -866,103 +866,108 @@ int klp_register_patch(struct klp_patch *patch)
}
EXPORT_SYMBOL_GPL(klp_register_patch);
-static int klp_module_notify_coming(struct klp_patch *patch,
- struct klp_object *obj)
+int klp_module_coming(struct module *mod)
{
- struct module *pmod = patch->mod;
- struct module *mod = obj->mod;
int ret;
+ struct klp_patch *patch;
+ struct klp_object *obj;
- ret = klp_init_object_loaded(patch, obj);
- if (ret) {
- pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
- pmod->name, mod->name, ret);
- return ret;
- }
+ if (WARN_ON(mod->state != MODULE_STATE_COMING))
+ return -EINVAL;
- if (patch->state == KLP_DISABLED)
- return 0;
+ mutex_lock(&klp_mutex);
+ /*
+ * Each module has to know that klp_module_coming()
+ * has been called. We never know what module will
+ * get patched by a new patch.
+ */
+ mod->klp_alive = true;
- pr_notice("applying patch '%s' to loading module '%s'\n",
- pmod->name, mod->name);
+ list_for_each_entry(patch, &klp_patches, list) {
+ klp_for_each_object(patch, obj) {
+ if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+ continue;
- ret = klp_enable_object(obj);
- if (ret)
- pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
- pmod->name, mod->name, ret);
- return ret;
-}
+ obj->mod = mod;
-static void klp_module_notify_going(struct klp_patch *patch,
- struct klp_object *obj)
-{
- struct module *pmod = patch->mod;
- struct module *mod = obj->mod;
+ ret = klp_init_object_loaded(patch, obj);
+ if (ret) {
+ pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+ patch->mod->name, obj->mod->name, ret);
+ goto err;
+ }
- if (patch->state == KLP_DISABLED)
- goto disabled;
+ if (patch->state == KLP_DISABLED)
+ break;
+
+ pr_notice("applying patch '%s' to loading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+
+ ret = klp_enable_object(obj);
+ if (ret) {
+ pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+ patch->mod->name, obj->mod->name, ret);
+ goto err;
+ }
+
+ break;
+ }
+ }
- pr_notice("reverting patch '%s' on unloading module '%s'\n",
- pmod->name, mod->name);
+ mutex_unlock(&klp_mutex);
- klp_disable_object(obj);
+ return 0;
-disabled:
+err:
+ /*
+ * If a patch is unsuccessfully applied, return
+ * error to the module loader.
+ */
+ pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
+ patch->mod->name, obj->mod->name, obj->mod->name);
klp_free_object_loaded(obj);
+ mutex_unlock(&klp_mutex);
+
+ return ret;
}
-static int klp_module_notify(struct notifier_block *nb, unsigned long action,
- void *data)
+/* Module can be either COMING or GOING */
+void klp_module_going(struct module *mod)
{
- int ret;
- struct module *mod = data;
struct klp_patch *patch;
struct klp_object *obj;
- if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING)
- return 0;
+ if (WARN_ON(mod->state != MODULE_STATE_GOING &&
+ mod->state != MODULE_STATE_COMING))
+ return;
mutex_lock(&klp_mutex);
-
/*
- * Each module has to know that the notifier has been called.
- * We never know what module will get patched by a new patch.
+ * Each module has to know that klp_module_going()
+ * has been called. We never know what module will
+ * get patched by a new patch.
*/
- if (action == MODULE_STATE_COMING)
- mod->klp_alive = true;
- else /* MODULE_STATE_GOING */
- mod->klp_alive = false;
+ mod->klp_alive = false;
list_for_each_entry(patch, &klp_patches, list) {
klp_for_each_object(patch, obj) {
if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
continue;
- if (action == MODULE_STATE_COMING) {
- obj->mod = mod;
- ret = klp_module_notify_coming(patch, obj);
- if (ret) {
- obj->mod = NULL;
- pr_warn("patch '%s' is in an inconsistent state!\n",
- patch->mod->name);
- }
- } else /* MODULE_STATE_GOING */
- klp_module_notify_going(patch, obj);
+ if (patch->state != KLP_DISABLED) {
+ pr_notice("reverting patch '%s' on unloading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+ klp_disable_object(obj);
+ }
+ klp_free_object_loaded(obj);
break;
}
}
mutex_unlock(&klp_mutex);
-
- return 0;
}
-static struct notifier_block klp_module_nb = {
- .notifier_call = klp_module_notify,
- .priority = INT_MIN+1, /* called late but before ftrace notifier */
-};
-
static int __init klp_init(void)
{
int ret;
@@ -973,21 +978,11 @@ static int __init klp_init(void)
return -EINVAL;
}
- ret = register_module_notifier(&klp_module_nb);
- if (ret)
- return ret;
-
klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
- if (!klp_root_kobj) {
- ret = -ENOMEM;
- goto unregister;
- }
+ if (!klp_root_kobj)
+ return -ENOMEM;
return 0;
-
-unregister:
- unregister_module_notifier(&klp_module_nb);
- return ret;
}
module_init(klp_init);
diff --git a/kernel/module.c b/kernel/module.c
index 1981ae0..932fb35 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -53,6 +53,7 @@
#include <asm/sections.h>
#include <linux/tracepoint.h>
#include <linux/ftrace.h>
+#include <linux/livepatch.h>
#include <linux/async.h>
#include <linux/percpu.h>
#include <linux/kmemleak.h>
@@ -984,6 +985,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
mod->exit();
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
+ klp_module_going(mod);
ftrace_release_mod(mod);
async_synchronize_full();
@@ -3258,6 +3260,7 @@ fail:
module_put(mod);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
+ klp_module_going(mod);
ftrace_release_mod(mod);
free_module(mod);
wake_up_all(&module_wq);
@@ -3314,7 +3317,13 @@ out_unlocked:
static int prepare_coming_module(struct module *mod)
{
+ int err;
+
ftrace_module_enable(mod);
+ err = klp_module_coming(mod);
+ if (err)
+ return err;
+
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
return 0;
@@ -3496,6 +3505,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
coming_cleanup:
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
+ klp_module_going(mod);
bug_cleanup:
/* module_bug_cleanup needs module_mutex protection */
--
2.4.3
On Fri 2016-03-11 15:03:48, Jessica Yu wrote:
> Remove the livepatch module notifier in favor of directly enabling and
> disabling patches to modules in the module loader. Hard-coding the
> function calls ensures that ftrace_module_enable() is run before
> klp_module_coming() during module load, and that klp_module_going() is
> run before ftrace_release_mod() during module unload. This way, ftrace
> and livepatch code is run in the correct order during the module
> load/unload sequence without dependence on the module notifier call chain.
>
> Signed-off-by: Jessica Yu <[email protected]>
> Acked-by: Josh Poimboeuf <[email protected]>
> Acked-by: Rusty Russell <[email protected]>
> ---
> include/linux/livepatch.h | 13 ++++
> kernel/livepatch/core.c | 147 ++++++++++++++++++++++------------------------
> kernel/module.c | 10 ++++
> 3 files changed, 94 insertions(+), 76 deletions(-)
>
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 780f00c..4fafbae 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -866,103 +866,108 @@ int klp_register_patch(struct klp_patch *patch)
> }
> EXPORT_SYMBOL_GPL(klp_register_patch);
>
> -static int klp_module_notify_coming(struct klp_patch *patch,
> - struct klp_object *obj)
> +int klp_module_coming(struct module *mod)
> {
> - struct module *pmod = patch->mod;
> - struct module *mod = obj->mod;
> int ret;
> + struct klp_patch *patch;
> + struct klp_object *obj;
>
> - ret = klp_init_object_loaded(patch, obj);
> - if (ret) {
> - pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
> - pmod->name, mod->name, ret);
> - return ret;
> - }
> + if (WARN_ON(mod->state != MODULE_STATE_COMING))
> + return -EINVAL;
>
> - if (patch->state == KLP_DISABLED)
> - return 0;
> + mutex_lock(&klp_mutex);
> + /*
> + * Each module has to know that klp_module_coming()
> + * has been called. We never know what module will
> + * get patched by a new patch.
> + */
> + mod->klp_alive = true;
>
> - pr_notice("applying patch '%s' to loading module '%s'\n",
> - pmod->name, mod->name);
> + list_for_each_entry(patch, &klp_patches, list) {
> + klp_for_each_object(patch, obj) {
> + if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
> + continue;
>
> - ret = klp_enable_object(obj);
> - if (ret)
> - pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
> - pmod->name, mod->name, ret);
> - return ret;
> -}
> + obj->mod = mod;
>
> -static void klp_module_notify_going(struct klp_patch *patch,
> - struct klp_object *obj)
> -{
> - struct module *pmod = patch->mod;
> - struct module *mod = obj->mod;
> + ret = klp_init_object_loaded(patch, obj);
> + if (ret) {
> + pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
> + patch->mod->name, obj->mod->name, ret);
> + goto err;
> + }
>
> - if (patch->state == KLP_DISABLED)
> - goto disabled;
> + if (patch->state == KLP_DISABLED)
> + break;
> +
> + pr_notice("applying patch '%s' to loading module '%s'\n",
> + patch->mod->name, obj->mod->name);
> +
> + ret = klp_enable_object(obj);
> + if (ret) {
> + pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
> + patch->mod->name, obj->mod->name, ret);
> + goto err;
> + }
> +
> + break;
> + }
> + }
>
> - pr_notice("reverting patch '%s' on unloading module '%s'\n",
> - pmod->name, mod->name);
> + mutex_unlock(&klp_mutex);
>
> - klp_disable_object(obj);
> + return 0;
>
> -disabled:
> +err:
> + /*
> + * If a patch is unsuccessfully applied, return
> + * error to the module loader.
> + */
> + pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
> + patch->mod->name, obj->mod->name, obj->mod->name);
One more thing. We should add here:
mod->klp_alive = true;
Otherwise, there is a small race window when a new patch will try to
patch the module.
> klp_free_object_loaded(obj);
> + mutex_unlock(&klp_mutex);
> +
> + return ret;
> }
With the above fix:
Reviewed-by: Petr Mladek <[email protected]>
Best Regards,
Petr
On Fri 2016-03-11 15:03:47, Jessica Yu wrote:
> Put all actions in complete_formation() that are performed after
> module->state is set to MODULE_STATE_COMING into a separate function
> prepare_coming_module(). This split prepares for the removal of the
> livepatch module notifiers in favor of hard-coding function calls to
> klp_module_{coming,going} in the module loader.
>
> The complete_formation -> prepare_coming_module split will also make error
> handling easier since we can jump to the appropriate error label to do any
> module GOING cleanup after all the COMING-actions have completed.
>
> Signed-off-by: Jessica Yu <[email protected]>
> Reviewed-by: Josh Poimboeuf <[email protected]>
> Acked-by: Rusty Russell <[email protected]>
> ---
> kernel/module.c | 26 ++++++++++++++++++--------
> 1 file changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 87cfeb2..1981ae0 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3312,6 +3312,14 @@ out_unlocked:
> return err;
> }
>
> +static int prepare_coming_module(struct module *mod)
> +{
> + ftrace_module_enable(mod);
> + blocking_notifier_call_chain(&module_notify_list,
> + MODULE_STATE_COMING, mod);
> + return 0;
> +}
Nit, just in case you send a new version. Please, move this below
complete_formation(). It is nice when the funtions are defined
in the same order as they are called :-)
It is a cosmetic change and it should not invalidate other acks.
In each case, the patch looks fine:
Reviewed-by: Petr Mladek <[email protected]>
Best Regards,
Petr
+++ Petr Mladek [14/03/16 16:06 +0100]:
>On Fri 2016-03-11 15:03:48, Jessica Yu wrote:
>> Remove the livepatch module notifier in favor of directly enabling and
>> disabling patches to modules in the module loader. Hard-coding the
>> function calls ensures that ftrace_module_enable() is run before
>> klp_module_coming() during module load, and that klp_module_going() is
>> run before ftrace_release_mod() during module unload. This way, ftrace
>> and livepatch code is run in the correct order during the module
>> load/unload sequence without dependence on the module notifier call chain.
>>
>> Signed-off-by: Jessica Yu <[email protected]>
>> Acked-by: Josh Poimboeuf <[email protected]>
>> Acked-by: Rusty Russell <[email protected]>
>> ---
>> include/linux/livepatch.h | 13 ++++
>> kernel/livepatch/core.c | 147 ++++++++++++++++++++++------------------------
>> kernel/module.c | 10 ++++
>> 3 files changed, 94 insertions(+), 76 deletions(-)
>>
>> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
>> index 780f00c..4fafbae 100644
>> --- a/kernel/livepatch/core.c
>> +++ b/kernel/livepatch/core.c
>> @@ -866,103 +866,108 @@ int klp_register_patch(struct klp_patch *patch)
>> }
>> EXPORT_SYMBOL_GPL(klp_register_patch);
>>
>> -static int klp_module_notify_coming(struct klp_patch *patch,
>> - struct klp_object *obj)
>> +int klp_module_coming(struct module *mod)
>> {
>> - struct module *pmod = patch->mod;
>> - struct module *mod = obj->mod;
>> int ret;
>> + struct klp_patch *patch;
>> + struct klp_object *obj;
>>
>> - ret = klp_init_object_loaded(patch, obj);
>> - if (ret) {
>> - pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
>> - pmod->name, mod->name, ret);
>> - return ret;
>> - }
>> + if (WARN_ON(mod->state != MODULE_STATE_COMING))
>> + return -EINVAL;
>>
>> - if (patch->state == KLP_DISABLED)
>> - return 0;
>> + mutex_lock(&klp_mutex);
>> + /*
>> + * Each module has to know that klp_module_coming()
>> + * has been called. We never know what module will
>> + * get patched by a new patch.
>> + */
>> + mod->klp_alive = true;
>>
>> - pr_notice("applying patch '%s' to loading module '%s'\n",
>> - pmod->name, mod->name);
>> + list_for_each_entry(patch, &klp_patches, list) {
>> + klp_for_each_object(patch, obj) {
>> + if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
>> + continue;
>>
>> - ret = klp_enable_object(obj);
>> - if (ret)
>> - pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
>> - pmod->name, mod->name, ret);
>> - return ret;
>> -}
>> + obj->mod = mod;
>>
>> -static void klp_module_notify_going(struct klp_patch *patch,
>> - struct klp_object *obj)
>> -{
>> - struct module *pmod = patch->mod;
>> - struct module *mod = obj->mod;
>> + ret = klp_init_object_loaded(patch, obj);
>> + if (ret) {
>> + pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
>> + patch->mod->name, obj->mod->name, ret);
>> + goto err;
>> + }
>>
>> - if (patch->state == KLP_DISABLED)
>> - goto disabled;
>> + if (patch->state == KLP_DISABLED)
>> + break;
>> +
>> + pr_notice("applying patch '%s' to loading module '%s'\n",
>> + patch->mod->name, obj->mod->name);
>> +
>> + ret = klp_enable_object(obj);
>> + if (ret) {
>> + pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
>> + patch->mod->name, obj->mod->name, ret);
>> + goto err;
>> + }
>> +
>> + break;
>> + }
>> + }
>>
>> - pr_notice("reverting patch '%s' on unloading module '%s'\n",
>> - pmod->name, mod->name);
>> + mutex_unlock(&klp_mutex);
>>
>> - klp_disable_object(obj);
>> + return 0;
>>
>> -disabled:
>> +err:
>> + /*
>> + * If a patch is unsuccessfully applied, return
>> + * error to the module loader.
>> + */
>> + pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
>> + patch->mod->name, obj->mod->name, obj->mod->name);
>
>One more thing. We should add here:
>
> mod->klp_alive = true;
>
>Otherwise, there is a small race window when a new patch will try to
>patch the module.
Ah, you are right. I think you meant false, though :-) Will fix that.
>> klp_free_object_loaded(obj);
>> + mutex_unlock(&klp_mutex);
>> +
>> + return ret;
>> }
>
>With the above fix:
>
>Reviewed-by: Petr Mladek <[email protected]>
>
>
>Best Regards,
>Petr
On Fri, Mar 11, 2016 at 03:03:48PM -0500, Jessica Yu wrote:
> +/* Module can be either COMING or GOING */
IMO this comment doesn't really add anything: the below WARN_ON already
says as much. Also the location of the comment right above the function
is confusing: someone not familiar with the code might wonder why the
function is called klp_module_going() if the module can be either coming
or going. So I think the comment can just be removed.
> +void klp_module_going(struct module *mod)
> {
> - int ret;
> - struct module *mod = data;
> struct klp_patch *patch;
> struct klp_object *obj;
>
> - if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING)
> - return 0;
> + if (WARN_ON(mod->state != MODULE_STATE_GOING &&
> + mod->state != MODULE_STATE_COMING))
> + return;
--
Josh
On Mon 2016-03-14 13:50:09, Jessica Yu wrote:
> +++ Petr Mladek [14/03/16 16:06 +0100]:
> >On Fri 2016-03-11 15:03:48, Jessica Yu wrote:
> >>+err:
> >>+ /*
> >>+ * If a patch is unsuccessfully applied, return
> >>+ * error to the module loader.
> >>+ */
> >>+ pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
> >>+ patch->mod->name, obj->mod->name, obj->mod->name);
> >
> >One more thing. We should add here:
> >
> > mod->klp_alive = true;
> >
> >Otherwise, there is a small race window when a new patch will try to
> >patch the module.
>
> Ah, you are right. I think you meant false, though :-) Will fix that.
Yeah, I meant false :-)
Thanks,
Petr