Re: [PATCH v7] rust: support for shadow call stack sanitizer

[Gary Guo <gary@garyguo.net>]

On Sun, 15 Sep 2024 09:32:44 +0200
Dirk Behme <dirk.behme@gmail.com> wrote:

> Yes, it is unrelated to this change. It is PREEMPT_RT usage related. I 
> think we could add something like
> 
> #ifdef CONFIG_PREEMPT_RT
> void rust_helper___mutex_init(struct mutex *mutex, const char *name,
> 			 struct lock_class_key *key)
> {
> 	return __mutex_init(mutex, name, key);
> }
> #endif

There's no need to use `ifdef` here (we don't want to try replicate all
ifdefs). Simply add a helper is sufficient. We have logic in
rust/bindings/lib.rs to prefer externed function to helpers if an
externed function exist.

Best,
Gary

> 
> to helpers to fix
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/rust/kernel/sync/lock/mutex.rs?&id=6d20d629c6d8575be98eeebe49a16fb2d7b32350
> 
> ?
> 
> Explanation: Looking at
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/mutex.h?#n52
> 
> we have (simplified)
> 
> #ifndef CONFIG_PREEMPT_RT
> extern void __mutex_init(struct mutex *lock, const char *name,
> 			 struct lock_class_key *key);
> #else
> #define __mutex_init(mutex, name, key)			\
> do {							\
> 	rt_mutex_base_init(&(mutex)->rtmutex);		\
> 	__mutex_rt_init((mutex), name, key);		\
> } while (0)
> #endif
> 
> So in the CONFIG_PREEMPT_RT case bindgen doesn't resolve the macro 
> what could be fixed by adding a helper.
> 
> Dirk