Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching

Pull livepatching updates from Jiri Kosina:

 - stacktrace handling improvements from Miroslav benes

 - debug output improvements from Petr Mladek

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
  livepatch: Remove duplicate warning about missing reliable stacktrace support
  Revert "livepatch: Remove reliable stacktrace check in klp_try_switch_task()"
  stacktrace: Remove weak version of save_stack_trace_tsk_reliable()
  livepatch: Use static buffer for debugging messages under rq lock
  livepatch: Remove stale kobj_added entries from kernel-doc descriptions

3 files changed, 8 insertions, 14 deletions

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index eeba421cc671..273400814020 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -35,7 +35,6 @@
  * @stack_node: list node for klp_ops func_stack list
  * @old_size:   size of the old function
  * @new_size:   size of the new function
- * @kobj_added: @kobj has been added and needs freeing
  * @nop:        temporary patch to use the original code again; dyn. allocated
  * @patched:    the func has been added to the klp_ops list
  * @transition: the func is currently being applied or reverted
@@ -113,7 +112,6 @@ struct klp_callbacks {
  * @node:       list node for klp_patch obj_list
  * @mod:        kernel module associated with the patched object
  *              (NULL for vmlinux)
- * @kobj_added: @kobj has been added and needs freeing
  * @dynamic:    temporary object for nop functions; dynamically allocated
  * @patched:    the object's funcs have been added to the klp_ops list
  */
@@ -140,7 +138,6 @@ struct klp_object {
  * @list:       list node for global list of actively used patches
  * @kobj:       kobject for sysfs resources
  * @obj_list:   dynamic list of the object entries
- * @kobj_added: @kobj has been added and needs freeing
  * @enabled:    the patch is enabled (but operation may be incomplete)
  * @forced:     was involved in a forced transition
  * @free_work:  patch cleanup from workqueue-context
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index abb2a4a2cbb2..cdf318d86dd6 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -247,7 +247,6 @@ static int klp_check_stack(struct task_struct *task, char *err_buf)
         int ret, nr_entries;
 
         ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
-        WARN_ON_ONCE(ret == -ENOSYS);
         if (ret < 0) {
                 snprintf(err_buf, STACK_ERR_BUF_SIZE,
                          "%s: %s:%d has an unreliable stack\n",
@@ -281,11 +280,11 @@ static int klp_check_stack(struct task_struct *task, char *err_buf)
  */
 static bool klp_try_switch_task(struct task_struct *task)
 {
+        static char err_buf[STACK_ERR_BUF_SIZE];
         struct rq *rq;
         struct rq_flags flags;
         int ret;
         bool success = false;
-        char err_buf[STACK_ERR_BUF_SIZE];
 
         err_buf[0] = '\0';
 
@@ -294,6 +293,13 @@ static bool klp_try_switch_task(struct task_struct *task)
                 return true;
 
         /*
+         * For arches which don't have reliable stack traces, we have to rely
+         * on other methods (e.g., switching tasks at kernel exit).
+         */
+        if (!klp_have_reliable_stack())
+                return false;
+
+        /*
          * Now try to check the stack for any to-be-patched or to-be-unpatched
          * functions.  If all goes well, switch the task to the target patch
          * state.
@@ -328,7 +334,6 @@ done:
                 pr_debug("%s", err_buf);
 
         return success;
-
 }
 
 /*
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index c8d0f05721a1..e6a02b274b73 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -255,14 +255,6 @@ save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
         WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
 }
 
-__weak int
-save_stack_trace_tsk_reliable(struct task_struct *tsk,
-                              struct stack_trace *trace)
-{
-        WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n");
-        return -ENOSYS;
-}
-
 /**
  * stack_trace_save - Save a stack trace into a storage array
  * @store:      Pointer to storage array