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livepatch: Don't block the removal of patches loaded after a forced transition

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module_put() is currently never called in klp_complete_transition() when
klp_force is set. As a result, we might keep the reference count even when
klp_enable_patch() fails and klp_cancel_transition() is called.

This might give the impression that a module might get blocked in some
strange init state. Fortunately, it is not the case. The reference count
is ignored when mod->init fails and erroneous modules are always removed.

Anyway, this might be confusing. Instead, this patch moves
the global klp_forced flag into struct klp_patch. As a result,
we block only modules that might still be in use after a forced
transition. Newly loaded livepatches might be eventually completely
removed later.

It is not a big deal. But the code is at least consistent with
the reality.

Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Petr Mladek 2019-01-09 13:43:22 +01:00 • committed by Jiri Kosina
parent 0430f78bf3
commit 68007289bf
4 changed files with 11 additions and 6 deletions
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2
include/linux/livepatch.h
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@ -143,6 +143,7 @@ struct klp_object {
* @kobj: kobject for sysfs resources
* @kobj_added: @kobj has been added and needs freeing
* @enabled: the patch is enabled (but operation may be incomplete)
* @forced: was involved in a forced transition
* @finish: for waiting till it is safe to remove the patch module
*/
struct klp_patch {
@ -155,6 +156,7 @@ struct klp_patch {
struct kobject kobj;
bool kobj_added;
bool enabled;
bool forced;
struct completion finish;
};