The following commit has been merged into the locking/core branch of tip:
Commit-ID: 36c2cf88808d47e926d11b98734f154fe4a9f50f
Gitweb: https://git.kernel.org/tip/36c2cf88808d47e926d11b98734f154fe4a9f50f
Author: David Lechner <dlechner@xxxxxxxxxxxx>
AuthorDate: Tue, 01 Oct 2024 17:30:18 -05:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 25 Oct 2024 10:01:51 +02:00
cleanup: Add conditional guard helper
Add a new if_not_guard() macro to cleanup.h for handling
conditional guards such as mutext_trylock().
This is more ergonomic than scoped_guard() for most use cases.
Instead of hiding the error handling statement in the macro args, it
works like a normal if statement and allow the error path to be indented
while the normal code flow path is not indented. And it avoid unwanted
side-effect from hidden for loop in scoped_guard().
Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
Co-developed-by: Fabio M. De Francesco <fabio.m.de.francesco@xxxxxxxxxxxxxxx>
Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20241001-cleanup-if_not_cond_guard-v1-1-7753810b0f7a@xxxxxxxxxxxx
---
include/linux/cleanup.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 0cc66f8..e859f79 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -273,6 +273,12 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
* an anonymous instance of the (guard) class, not recommended for
* conditional locks.
*
+ * if_not_guard(name, args...) { <error handling> }:
+ * convenience macro for conditional guards that calls the statement that
+ * follows only if the lock was not acquired (typically an error return).
+ *
+ * Only for conditional locks.
+ *
* scoped_guard (name, args...) { }:
* similar to CLASS(name, scope)(args), except the variable (with the
* explicit name 'scope') is declard in a for-loop such that its scope is
@@ -343,6 +349,15 @@ _label: \
#define scoped_cond_guard(_name, _fail, args...) \
__scoped_cond_guard(_name, _fail, __UNIQUE_ID(label), args)
+
+#define __if_not_guard(_name, _id, args...) \
+ BUILD_BUG_ON(!__is_cond_ptr(_name)); \
+ CLASS(_name, _id)(args); \
+ if (!__guard_ptr(_name)(&_id))
+
+#define if_not_guard(_name, args...) \
+ __if_not_guard(_name, __UNIQUE_ID(guard), args)
+
/*
* Additional helper macros for generating lock guards with types, either for
* locks that don't have a native type (eg. RCU, preempt) or those that need a
|