• Petr Mladek's avatar
    livepatch: Correctly call klp_post_unpatch_callback() in error paths · 5aaf1ab5
    Petr Mladek authored
    The post_unpatch_enabled flag in struct klp_callbacks is set when a
    pre-patch callback successfully executes, indicating that we need to
    call a corresponding post-unpatch callback when the patch is reverted.
    This is true for ordinary patch disable as well as the error paths of
    klp_patch_object() callers.
    
    As currently coded, we inadvertently execute the post-patch callback
    twice in klp_module_coming() when klp_patch_object() fails:
    
      - We explicitly call klp_post_unpatch_callback() for the failed object
      - We call it again for the same object (and all the others) via
        klp_cleanup_module_patches_limited()
    
    We should clear the flag in klp_post_unpatch_callback() to make
    sure that the callback is not called twice. It makes the API
    more safe.
    
    (We could have removed the callback from the former error path as it
    would be covered by the latter call, but I think that is is cleaner to
    clear the post_unpatch_enabled after its invoked. For example, someone
    might later decide to call the callback only when obj->patched flag is
    set.)
    
    There is another mistake in the error path of klp_coming_module() in
    which it skips the post-unpatch callback for the klp_transition_patch.
    However, the pre-patch callback was called even for this patch, so be
    sure to make the corresponding callbacks for all patches.
    
    Finally, I used this opportunity to make klp_pre_patch_callback() more
    readable.
    
    [jkosina@suse.cz: incorporate changelog wording changes proposed by Joe Lawrence]
    Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
    Acked-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
    Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
    5aaf1ab5
core.h 988 Bytes