In case CONFIG_PREEMPT_RT is enabled __mutex_init() becomes a macro
instead of an extern function (simplified from
include/linux/mutex.h):
#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
The macro isn't resolved by bindgen, then. What results in a build
error:
error[E0425]: cannot find function `__mutex_init` in crate `bindings`
--> rust/kernel/sync/lock/mutex.rs:104:28
|
104 | unsafe { bindings::__mutex_init(ptr, name, key) }
| ^^^^^^^^^^^^ help: a function with a similar name exists: `__mutex_rt_init`
|
::: rust/bindings/bindings_generated.rs:23722:5
|
23722 | / pub fn __mutex_rt_init(
23723 | | lock: *mut mutex,
23724 | | name: *const core::ffi::c_char,
23725 | | key: *mut lock_class_key,
23726 | | );
| |_____- similarly named function `__mutex_rt_init` defined here
Fix this by adding a helper.
As explained by Gary Guo in [1] no #ifdef CONFIG_PREEMPT_RT
is needed here as rust/bindings/lib.rs prefers externed function to
helpers if an externed function exists.
Reported-by: Conor Dooley <conor@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/20240913-shack-estate-b376a65921b1@spud/
Link: https://lore.kernel.org/rust-for-linux/20240915123626.1a170103.gary@garyguo.net/ [1]
Fixes: 6d20d629c6 ("rust: lock: introduce `Mutex`")
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240916073752.3123484-1-dirk.behme@de.bosch.com
[ Reworded to include the proper example by Dirk. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
d065cc7605