[PATCH bpf-next v2 05/26] rqspinlock: Add rqspinlock.h header

Kumar Kartikeya Dwivedi
2025-02-06T10:54:45Z

This header contains the public declarations usable in the rest of the
kernel for rqspinlock.

Let's also type alias qspinlock to rqspinlock_t to ensure consistent use
of the new lock type. We want to remove dependence on the qspinlock type
in later patches as we need to provide a test-and-set fallback, hence
begin abstracting away from now onwards.

Reviewed-by: Barret Rhoden <brho@google.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
include/asm-generic/rqspinlock.h | 19 +++++++++++++++++++
kernel/locking/rqspinlock.c | 3 ++-
2 files changed, 21 insertions(+), 1 deletion(-)
create mode 100644 include/asm-generic/rqspinlock.h

diff --git a/include/asm-generic/rqspinlock.h b/include/asm-generic/rqspinlock.h
new file mode 100644
index 000000000000..54860b519571
--- /dev/null
+++ b/include/asm-generic/rqspinlock.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Resilient Queued Spin Lock
+ *
+ * (C) Copyright 2024 Meta Platforms, Inc. and affiliates.
+ *
+ * Authors: Kumar Kartikeya Dwivedi <memxor@gmail.com>
+ */
+#ifndef __ASM_GENERIC_RQSPINLOCK_H
+#define __ASM_GENERIC_RQSPINLOCK_H
+
+#include <linux/types.h>
+
+struct qspinlock;
+typedef struct qspinlock rqspinlock_t;
+
+extern void resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val);
+
+#endif /* __ASM_GENERIC_RQSPINLOCK_H */
diff --git a/kernel/locking/rqspinlock.c b/kernel/locking/rqspinlock.c
index caaa7c9bbc79..18eb9ef3e908 100644
--- a/kernel/locking/rqspinlock.c
+++ b/kernel/locking/rqspinlock.c
@@ -23,6 +23,7 @@
#include <asm/byteorder.h>
#include <asm/qspinlock.h>
#include <trace/events/lock.h>
+#include <asm/rqspinlock.h>

/*
* Include queued spinlock definitions and statistics code
@@ -127,7 +128,7 @@ static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock,
* contended : (*,x,y) +--> (*,0,0) ---> (*,0,1) -' :
* queue : ^--' :
*/
-void __lockfunc resilient_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
+void __lockfunc resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val)
{
struct mcs_spinlock *prev, *next, *node;
u32 old, tail;
--
2.43.5