[PATCH 1/2 v4] cleanup: Add cond_guard() to conditional guards

Fabio M. De Francesco
2024-02-08T13:04:37Z

Add cond_guard() macro to conditional guards.

cond_guard() is a guard to be used with the conditional variants of locks,
like down_read_trylock() or mutex_lock_interruptible().

It takes a statement (or statement-expression) that is passed as its
second argument. That statement (or statement-expression) is executed if
waiting for a lock is interrupted or if a _trylock() fails in case of
contention.

Usage example:

cond_guard(mutex_intr, return -EINTR, &mutex);

Consistent with other usage of _guard(), locks are unlocked at the exit of the
scope where cond_guard() is called.

Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@linux.intel.com>
---
include/linux/cleanup.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index c2d09bc4f976..7b54ee996414 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -134,6 +134,16 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
* an anonymous instance of the (guard) class, not recommended for
* conditional locks.
*
+ * cond_guard(name, fail, args...):
+ * a guard to be used with the conditional variants of locks, like
+ * down_read_trylock() or mutex_lock_interruptible. 'fail' is a
+ * statement or statement-expression that is executed if waiting for a
+ * lock is interrupted or if a _trylock() fails in case of contention.
+ *
+ * Example:
+ *
+ * cond_guard(mutex_intr, return -EINTR, &mutex);
+ *
* 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
@@ -165,6 +175,11 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \

#define __guard_ptr(_name) class_##_name##_lock_ptr

+#define cond_guard(_name, _fail, args...) \
+ CLASS(_name, scope)(args); \
+ if (!__guard_ptr(_name)(&scope)) _fail; \
+ else { }
+
#define scoped_guard(_name, args...) \
for (CLASS(_name, scope)(args), \
*done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
--
2.43.0