Re: [PATCH v5 08/36] locking/rwlock, spinlock: Support Clang's context analysis

[Bart Van Assche]

On 12/19/25 7:39 AM, Marco Elver wrote:

- extern void do_raw_read_lock(rwlock_t *lock) __acquires(lock);
+ extern void do_raw_read_lock(rwlock_t *lock) __acquires_shared(lock);

Given the "one change per patch" rule, shouldn't the annotation fixes
for rwlock operations be moved into a separate patch?

-typedef struct {
+context_lock_struct(rwlock) {
        arch_rwlock_t raw_lock;
  #ifdef CONFIG_DEBUG_SPINLOCK
        unsigned int magic, owner_cpu;
@@ -31,7 +31,8 @@ typedef struct {
  #ifdef CONFIG_DEBUG_LOCK_ALLOC
        struct lockdep_map dep_map;
  #endif
-} rwlock_t;
+};
+typedef struct rwlock rwlock_t;

This change introduces a new globally visible "struct rwlock". Although
I haven't found any existing "struct rwlock" definitions, maybe it's a
good idea to use a more unique name instead.

diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h
index 819aeba1c87e..018f5aabc1be 100644
--- a/include/linux/spinlock_api_up.h
+++ b/include/linux/spinlock_api_up.h
@@ -24,68 +24,77 @@
   * flags straight, to suppress compiler warnings of unused lock
   * variables, and to add the proper checker annotations:
   */
-#define ___LOCK(lock) \
-  do { __acquire(lock); (void)(lock); } while (0)
+#define ___LOCK_void(lock) \
+  do { (void)(lock); } while (0)

Instead of introducing a new macro ___LOCK_void(), please expand this
macro where it is used ((void)(lock)). I think this will make the code
in this header file easier to read.
   > -#define __LOCK(lock) \

-  do { preempt_disable(); ___LOCK(lock); } while (0)
+#define ___LOCK_(lock) \
+  do { __acquire(lock); ___LOCK_void(lock); } while (0)

Is the macro ___LOCK_() used anywhere? If not, can it be left out?

-#define __LOCK_BH(lock) \
-  do { __local_bh_disable_ip(_THIS_IP_, SOFTIRQ_LOCK_OFFSET); ___LOCK(lock); } 
while (0)
+#define ___LOCK_shared(lock) \
+  do { __acquire_shared(lock); ___LOCK_void(lock); } while (0)

The introduction of the new macros in this header file make the changes
hard to follow. Please consider splitting the changes for this header
file as follows:
* A first patch that splits ___LOCK() into ___LOCK_exclusive() and
  ___LOCK_shared().
* A second patch with the thread-safety annotation changes
  (__acquire() -> __acquire_shared()).

  /* Non PREEMPT_RT kernels map spinlock to raw_spinlock */
-typedef struct spinlock {
+context_lock_struct(spinlock) {
        union {
                struct raw_spinlock rlock;

@@ -26,7 +26,8 @@ typedef struct spinlock {

                };
  #endif
        };
-} spinlock_t;
+};
+typedef struct spinlock spinlock_t;

Also here, a new global struct name is introduced (spinlock). Maybe the
name of this new struct should be made more unique?

Thanks,

Bart.