Re: [PATCH] Locking: Let PREEMPT_RT compile again with new rwsem asserts.

From: Waiman Long
Date: Tue Mar 19 2024 - 11:54:22 EST



On 3/19/24 10:15, Sebastian Andrzej Siewior wrote:
On 2024-03-19 13:38:06 [+0000], Matthew Wilcox wrote:
On Tue, Mar 19, 2024 at 08:05:50AM +0100, Sebastian Andrzej Siewior wrote:
-static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
+static __always_inline bool rwsem_held_write(const struct rw_semaphore *sem)
The locking maintainers were very clear that this predicate Should Not
Exist. It encourages people to write bad code. Assertions only!
What do you refer to? The inline vs __always_inline or
rwsem_held_write() should not exists and it should invoke directly
rw_base_is_write_locked()?

Just merge rwsem_held_write() into rwsem_assert_held_write_nolockdep() and we should be all set.

Cheers,
Longman

{
- rw_base_assert_held_write(sem);
+ return rw_base_is_write_locked(&sem->rwbase);
+}
+
+static __always_inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
+{
+ WARN_ON(!rwsem_held_write(sem));
}
static __always_inline int rwsem_is_contended(struct rw_semaphore *sem)
Sebastian