[PATCH] lockdep: add a hint for "INFO: trying to register non-static key." message

[PATCH] lockdep: add a hint for "INFO: trying to register non-static key." message

[Tetsuo Handa]

Since this message is printed when dynamically allocated spinlocks (e.g.
kzalloc()) are used without initialization (e.g. spin_lock_init()),
suggest developers to check whether initialization functions for objects
are called, before making developers wonder what annotation is missing.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 kernel/locking/lockdep.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c6d0c1dc6253..44c549f5c061 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -931,6 +931,7 @@ static bool assign_lock_key(struct lockdep_map *lock)
 		debug_locks_off();
 		pr_err("INFO: trying to register non-static key.\n");
 		pr_err("the code is fine but needs lockdep annotation.\n");
+		pr_err("maybe you didn't initialize this object before you use?\n");
 		pr_err("turning off the locking correctness validator.\n");
 		dump_stack();
 		return false;
-- 
2.18.4

[tip: perf/urgent] lockdep: Add a missing initialization hint to the "INFO: Trying to register non-static key" message

[tip-bot2 for Tetsuo Handa]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     3a85969e9d912d5dd85362ee37b5f81266e00e77
Gitweb:        https://git.kernel.org/tip/3a85969e9d912d5dd85362ee37b5f81266e00e77
Author:        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
AuthorDate:    Sun, 21 Mar 2021 15:49:13 +09:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sun, 21 Mar 2021 11:59:57 +01:00

lockdep: Add a missing initialization hint to the "INFO: Trying to register non-static key" message

Since this message is printed when dynamically allocated spinlocks (e.g.
kzalloc()) are used without initialization (e.g. spin_lock_init()),
suggest to developers to check whether initialization functions for objects
were called, before making developers wonder what annotation is missing.

[ mingo: Minor tweaks to the message. ]

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210321064913.4619-1-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/locking/lockdep.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c6d0c1d..c30eb88 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -930,7 +930,8 @@ static bool assign_lock_key(struct lockdep_map *lock)
 		/* Debug-check: all keys must be persistent! */
 		debug_locks_off();
 		pr_err("INFO: trying to register non-static key.\n");
-		pr_err("the code is fine but needs lockdep annotation.\n");
+		pr_err("The code is fine but needs lockdep annotation, or maybe\n");
+		pr_err("you didn't initialize this object before use?\n");
 		pr_err("turning off the locking correctness validator.\n");
 		dump_stack();
 		return false;

Re: [PATCH] lockdep: add a hint for "INFO: trying to register non-static key." message

[Waiman Long]

On 3/21/21 2:49 AM, Tetsuo Handa wrote:
> Since this message is printed when dynamically allocated spinlocks (e.g.
> kzalloc()) are used without initialization (e.g. spin_lock_init()),
> suggest developers to check whether initialization functions for objects
> are called, before making developers wonder what annotation is missing.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
>   kernel/locking/lockdep.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index c6d0c1dc6253..44c549f5c061 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -931,6 +931,7 @@ static bool assign_lock_key(struct lockdep_map *lock)
>   		debug_locks_off();
>   		pr_err("INFO: trying to register non-static key.\n");
>   		pr_err("the code is fine but needs lockdep annotation.\n");
> +		pr_err("maybe you didn't initialize this object before you use?\n");
>   		pr_err("turning off the locking correctness validator.\n");
>   		dump_stack();
>   		return false;

The only way this message is written is when the appropriate lock init 
function isn't called for locks in dynamically allocated objects. I 
think you can just say so without the word "maybe". Like "the code is 
fine but needs lockdep annotation by calling appropriate lock 
initialization function.".

Cheers,
Longman