Re: [PATCH v8 2/2] locking/lockdep: Test no new string literal is created in lockdep_set_subclass()
From: Boqun Feng
Date: Tue Sep 10 2024 - 05:56:29 EST
Hi Ahmed,
On Thu, Sep 05, 2024 at 04:12:20AM +0300, Ahmed Ehab wrote:
> Add a test case to ensure that no new name string literal will be
> created in lockdep_set_subclass(), otherwise a warning will be triggered
> in look_up_lock_class(). Add this to catch the problem in the future.
>
This overall looks good to me, I'm going to take it and create a PR for
tip in next release. However, please note a few things:
* Since you only send one of the patch from your original series, you
should avoid use "2/2" in the title, because it could be confusing
whether there is "1/2" lost in sending. If you want to make sure
people aware that this is a continued work of the patch #2 in your
original series, you can put some description after the following
"---"
* You need also to put changes between patch versions after "---" so
that people can know the context, for example, I have no idea why you
send a v8 after v7 and what's the delta here. Here is an example of
how to document the delta:
https://lore.kernel.org/rust-for-linux/20240827-static-mutex-v2-1-17fc32b20332@xxxxxxxxxx/
Regards,
Boqun
> Signed-off-by: Ahmed Ehab <bottaawesome633@xxxxxxxxx>
> ---
> lib/locking-selftest.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
> index 6f6a5fc85b42..0783ee97c971 100644
> --- a/lib/locking-selftest.c
> +++ b/lib/locking-selftest.c
> @@ -2710,6 +2710,44 @@ static void local_lock_3B(void)
>
> }
>
> +#if CONFIG_DEBUG_LOCK_ALLOC
> +static inline const char *rw_semaphore_lockdep_name(struct rw_semaphore *rwsem)
> +{
> + return rwsem->dep_map.name;
> +}
> +#else
> +static inline const char *rw_semaphore_lockdep_name(struct rw_semaphore *rwsem)
> +{
> + return NULL;
> +}
> +#endif
> +
> +static void lock_class_subclass_X1(void)
> +{
> + const char *name_before_setting_subclass = rw_semaphore_lockdep_name(&rwsem_X1);
> + const char *name_after_setting_subclass;
> +
> + lockdep_set_subclass(&rwsem_X1, 1);
> + name_after_setting_subclass = rw_semaphore_lockdep_name(&rwsem_X1);
> + DEBUG_LOCKS_WARN_ON(name_before_setting_subclass != name_after_setting_subclass);
> +}
> +
> +/*
> + * after setting the subclass the lockdep_map.name changes
> + * if we initialize a new string literal for the subclass
> + * we will have a new name pointer
> + */
> +static void class_subclass_X1_name_test(void)
> +{
> + printk(" --------------------------------------------------------------------------\n");
> + printk(" | class and subclass name test|\n");
> + printk(" ---------------------\n");
> +
> + print_testname("lock class and subclass same name");
> + dotest(lock_class_subclass_X1, SUCCESS, LOCKTYPE_RWSEM);
> + pr_cont("\n");
> +}
> +
> static void local_lock_tests(void)
> {
> printk(" --------------------------------------------------------------------------\n");
> @@ -2920,6 +2958,8 @@ void locking_selftest(void)
> dotest(hardirq_deadlock_softirq_not_deadlock, FAILURE, LOCKTYPE_SPECIAL);
> pr_cont("\n");
>
> + class_subclass_X1_name_test();
> +
> if (unexpected_testcase_failures) {
> printk("-----------------------------------------------------------------\n");
> debug_locks = 0;
> --
> 2.46.0
>