[PATCH v4 3/3] livepatch: add transition notices

[Joe Lawrence]

Log a few kernel debug messages at the beginning of the following livepatch
transition functions:

  klp_complete_transition()
  klp_cancel_transition()
  klp_init_transition()
  klp_reverse_transition()

Also update the log notice message in klp_start_transition() for similar
verbiage as the above messages.

Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Suggested-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 kernel/livepatch/transition.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 53887f0bca10..3d44a3cf27be 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -82,6 +82,10 @@ static void klp_complete_transition(void)
 	unsigned int cpu;
 	bool immediate_func = false;
 
+	pr_debug("'%s': completing %s transition\n",
+		 klp_transition_patch->mod->name,
+		 klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
+
 	if (klp_target_state == KLP_UNPATCHED) {
 		/*
 		 * All tasks have transitioned to KLP_UNPATCHED so we can now
@@ -163,6 +167,9 @@ void klp_cancel_transition(void)
 	if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED))
 		return;
 
+	pr_debug("'%s': canceling transition, unpatching\n",
+		 klp_transition_patch->mod->name);
+
 	klp_target_state = KLP_UNPATCHED;
 	klp_complete_transition();
 }
@@ -441,7 +448,8 @@ void klp_start_transition(void)
 
 	WARN_ON_ONCE(klp_target_state == KLP_UNDEFINED);
 
-	pr_notice("'%s': %s...\n", klp_transition_patch->mod->name,
+	pr_notice("'%s': starting %s transition\n",
+		  klp_transition_patch->mod->name,
 		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
 
 	/*
@@ -489,6 +497,9 @@ void klp_init_transition(struct klp_patch *patch, int state)
 
 	WARN_ON_ONCE(klp_target_state != KLP_UNDEFINED);
 
+	pr_debug("'%s': initializing %s transition\n", patch->mod->name,
+		 klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
+
 	klp_transition_patch = patch;
 
 	/*
@@ -562,6 +573,11 @@ void klp_reverse_transition(void)
 	unsigned int cpu;
 	struct task_struct *g, *task;
 
+	pr_debug("'%s': reversing transition from %s\n",
+		 klp_transition_patch->mod->name,
+		 klp_target_state == KLP_PATCHED ? "patching to unpatching" :
+						   "unpatching to patching");
+
 	klp_transition_patch->enabled = !klp_transition_patch->enabled;
 
 	klp_target_state = !klp_target_state;
-- 
1.8.3.1