6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dirk Behme dirk.behme@de.bosch.com
[ Upstream commit d065cc76054d21e48a839a2a19ba99dbc51a4d11 ]
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@sp... Link: https://lore.kernel.org/rust-for-linux/20240915123626.1a170103.gary@garyguo.... [1] Fixes: 6d20d629c6d8 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- rust/helpers/mutex.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/rust/helpers/mutex.c b/rust/helpers/mutex.c index 200db7e6279f0..a17ca8cdb50ca 100644 --- a/rust/helpers/mutex.c +++ b/rust/helpers/mutex.c @@ -7,3 +7,9 @@ void rust_helper_mutex_lock(struct mutex *lock) { mutex_lock(lock); } + +void rust_helper___mutex_init(struct mutex *mutex, const char *name, + struct lock_class_key *key) +{ + __mutex_init(mutex, name, key); +}