[tip: locking/core] kcsan, debugfs: Move debugfs file creation out of early init

[tip-bot2 for Marco Elver]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     e36299efe7d749976fbdaaf756dee6ef32543c2c
Gitweb:        https://git.kernel.org/tip/e36299efe7d749976fbdaaf756dee6ef32543c2c
Author:        Marco Elver <elver@xxxxxxxxxx>
AuthorDate:    Wed, 03 Mar 2021 10:38:45 +01:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 08 Mar 2021 14:27:43 -08:00

kcsan, debugfs: Move debugfs file creation out of early init

Commit 56348560d495 ("debugfs: do not attempt to create a new file
before the filesystem is initalized") forbids creating new debugfs files
until debugfs is fully initialized.  This means that KCSAN's debugfs
file creation, which happened at the end of __init(), no longer works.
And was apparently never supposed to work!

However, there is no reason to create KCSAN's debugfs file so early.
This commit therefore moves its creation to a late_initcall() callback.

Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Fixes: 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized")
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/kcsan/core.c    | 2 --
 kernel/kcsan/debugfs.c | 4 +++-
 kernel/kcsan/kcsan.h   | 5 -----
 3 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 3bf98db..23e7acb 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -639,8 +639,6 @@ void __init kcsan_init(void)
 
 	BUG_ON(!in_task());
 
-	kcsan_debugfs_init();
-
 	for_each_possible_cpu(cpu)
 		per_cpu(kcsan_rand_state, cpu) = (u32)get_cycles();
 
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 3c8093a..209ad8d 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -261,7 +261,9 @@ static const struct file_operations debugfs_ops =
 	.release = single_release
 };
 
-void __init kcsan_debugfs_init(void)
+static void __init kcsan_debugfs_init(void)
 {
 	debugfs_create_file("kcsan", 0644, NULL, NULL, &debugfs_ops);
 }
+
+late_initcall(kcsan_debugfs_init);
diff --git a/kernel/kcsan/kcsan.h b/kernel/kcsan/kcsan.h
index 8d4bf34..87ccdb3 100644
--- a/kernel/kcsan/kcsan.h
+++ b/kernel/kcsan/kcsan.h
@@ -31,11 +31,6 @@ void kcsan_save_irqtrace(struct task_struct *task);
 void kcsan_restore_irqtrace(struct task_struct *task);
 
 /*
- * Initialize debugfs file.
- */
-void kcsan_debugfs_init(void);
-
-/*
  * Statistics counters displayed via debugfs; should only be modified in
  * slow-paths.
  */