This is a note to let you know that I've just added the patch titled
rust: mutex: fix __mutex_init() usage in case of PREEMPT_RT
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rust-mutex-fix-__mutex_init-usage-in-case-of-preempt.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b02ff80e55d1439c24dd1b86b5797f02ebac190d
Author: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
Date: Mon Sep 16 09:37:52 2024 +0200
rust: mutex: fix __mutex_init() usage in case of PREEMPT_RT
[ 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@xxxxxxxxxx>
Link: https://lore.kernel.org/rust-for-linux/20240913-shack-estate-b376a65921b1@spud/
Link: https://lore.kernel.org/rust-for-linux/20240915123626.1a170103.gary@xxxxxxxxxxx/ [1]
Fixes: 6d20d629c6d8 ("rust: lock: introduce `Mutex`")
Signed-off-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
Tested-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240916073752.3123484-1-dirk.behme@xxxxxxxxxxxx
[ Reworded to include the proper example by Dirk. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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);
+}
