The atomic replace allows to create cumulative patches. They are useful when you maintain many livepatches and want to remove one that is lower on the stack. In addition it is very useful when more patches touch the same function and there are dependencies between them.
Changes against v9: + Fixed check of valid NOPs for already loaded objects, regression introduced in v9 [Joe, Mirek] + Allow to replace even disabled patches [Evgenii] Changes against v8: + Fixed handling of statically defined struct klp_object with empty array of functions [Joe, Mirek] + Removed redundant func->new_func assignment for NOPs [Mirek] + Improved some wording [Mirek] Changes against v7: + Fixed handling of NOPs for not-yet-loaded modules + Made klp_replaced_patches list static [Mirek] + Made klp_free_object() public later [Mirek] + Fixed several reported typos [Mirek, Joe] + Updated documentation according to the feedback [Joe] + Added some Acks [Mirek] Changes against v6: + used list_move when disabling replaced patches [Jason] + renamed KLP_FUNC_ORIGINAL -> KLP_FUNC_STATIC [Mirek] + used klp_is_func_type() in klp_unpatch_object() [Mirek] + moved static definition of klp_get_or_add_object() [Mirek] + updated comment about synchronization in forced mode [Mirek] + added user documentation + fixed several typos Jason Baron (5): livepatch: Use lists to manage patches, objects and functions livepatch: Initial support for dynamic structures livepatch: Allow to unpatch only functions of the given type livepatch: Support separate list for replaced patches. livepatch: Add atomic replace Petr Mladek (5): livepatch: Free only structures with initialized kobject livepatch: Correctly handle atomic replace for not yet loaded modules livepatch: Improve dynamic struct klp_object detection and manipulation livepatch: Allow to replace even disabled patches livepatch: Atomic replace and cumulative patches documentation Documentation/livepatch/cumulative-patches.txt | 83 +++++ include/linux/livepatch.h | 65 +++- kernel/livepatch/core.c | 422 ++++++++++++++++++++++--- kernel/livepatch/core.h | 4 + kernel/livepatch/patch.c | 31 +- kernel/livepatch/patch.h | 4 +- kernel/livepatch/transition.c | 41 ++- 7 files changed, 598 insertions(+), 52 deletions(-) create mode 100644 Documentation/livepatch/cumulative-patches.txt -- 2.13.6