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livepatch: Keep replaced patches until post_patch callback is called

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Pre/post (un)patch callbacks might manipulate the system state. Cumulative
livepatches might need to take over the changes made by the replaced
ones. For this they might need to access some data stored or referenced
by the old livepatches.

Therefore the replaced livepatches have to stay around until post_patch()
callback is called. It is achieved by calling the free functions later.
It is the same location where disabled livepatches have already been
freed.

Link: http://lkml.kernel.org/r/20191030154313.13263-2-pmladek@suse.com
To: Jiri Kosina <jikos@kernel.org>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: live-patching@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Petr Mladek
2019-10-30 16:43:09 +01:00
parent 9f7582d15f
commit 7e35e4eb7e
3 changed files with 35 additions and 18 deletions
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12
kernel/livepatch/transition.c
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@@ -78,7 +78,7 @@ static void klp_complete_transition(void)
klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
if (klp_transition_patch->replace && klp_target_state == KLP_PATCHED) {
klp_discard_replaced_patches(klp_transition_patch);
klp_unpatch_replaced_patches(klp_transition_patch);
klp_discard_nops(klp_transition_patch);
}
@@ -446,14 +446,14 @@ void klp_try_complete_transition(void)
klp_complete_transition();
/*
* It would make more sense to free the patch in
* It would make more sense to free the unused patches in
* klp_complete_transition() but it is called also
* from klp_cancel_transition().
*/
if (!patch->enabled) {
klp_free_patch_start(patch);
schedule_work(&patch->free_work);
}
if (!patch->enabled)
klp_free_patch_async(patch);
else if (patch->replace)
klp_free_replaced_patches_async(patch);
}
/*