module_put() is not called for a patch with "forced" flag. It should
block the removal of the livepatch module when the code might still
be in use after forced transition.
klp_force_transition() currently sets "forced" flag for all patches on
the list.
In fact, any patch can be safely unloaded when it passed through
the consistency model in KLP_UNPATCHED transition.
By other words, the "forced" flag must be set only for livepatches
that are being removed. In particular, set the "forced" flag:
+ only for klp_transition_patch when the transition to KLP_UNPATCHED
state was forced.
+ all replaced patches when the transition to KLP_PATCHED state was
forced and the patch was replacing the existing patches.
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
---
Changes in v3:
- rewrite more clear commit message by Petr.
Changes in v2:
- interact nicely with the atomic replace feature noted by Miroslav.
---
kernel/livepatch/transition.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 5683ac0d2566..7f25a5ae89f6 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -641,6 +641,18 @@ void klp_force_transition(void)
for_each_possible_cpu(cpu)
klp_update_patch_state(idle_task(cpu));
- klp_for_each_patch(patch)
- patch->forced = true;
+ /*
+ * Only need to set forced flag for the transition patch
+ * when force transition to KLP_UNPATCHED state, but
+ * have to set forced flag for all replaced patches
+ * when force atomic replace transition.
+ */
+ if (klp_target_state == KLP_UNPATCHED)
+ klp_transition_patch->forced = true;
+ else if (klp_transition_patch->replace) {
+ klp_for_each_patch(patch) {
+ if (patch != klp_transition_patch)
+ patch->forced = true;
+ }
+ }
}
--
2.20.1
