Re: [patch V5 09/16] futex: Add support for unlocking robust futexes

From: Peter Zijlstra

Date: Wed Jun 03 2026 - 05:32:28 EST


On Wed, Jun 03, 2026 at 10:22:20AM +0200, Peter Zijlstra wrote:

> Would you mind terribly if I did: 's/UNLOCK_ROBUST/ROBUST_UNLOCK/g' on
> the whole series?

--- a/include/uapi/linux/futex.h
+++ b/include/uapi/linux/futex.h
@@ -25,11 +25,11 @@

#define FUTEX_PRIVATE_FLAG 128
#define FUTEX_CLOCK_REALTIME 256
-#define FUTEX_UNLOCK_ROBUST 512
+#define FUTEX_ROBUST_UNLOCK 512
#define FUTEX_ROBUST_LIST32 1024

#define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME | \
- FUTEX_UNLOCK_ROBUST | FUTEX_ROBUST_LIST32)
+ FUTEX_ROBUST_UNLOCK | FUTEX_ROBUST_LIST32)

#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
@@ -49,23 +49,23 @@
* Operations to unlock a futex, clear the robust list pending op pointer and
* wake waiters.
*/
-#define FUTEX_UNLOCK_PI_LIST64 (FUTEX_UNLOCK_PI | FUTEX_UNLOCK_ROBUST)
+#define FUTEX_UNLOCK_PI_LIST64 (FUTEX_UNLOCK_PI | FUTEX_ROBUST_UNLOCK)
#define FUTEX_UNLOCK_PI_LIST64_PRIVATE (FUTEX_UNLOCK_PI_LIST64 | FUTEX_PRIVATE_FLAG)
-#define FUTEX_UNLOCK_PI_LIST32 (FUTEX_UNLOCK_PI | FUTEX_UNLOCK_ROBUST | \
+#define FUTEX_UNLOCK_PI_LIST32 (FUTEX_UNLOCK_PI | FUTEX_ROBUST_UNLOCK | \
FUTEX_ROBUST_LIST32)
#define FUTEX_UNLOCK_PI_LIST32_PRIVATE (FUTEX_UNLOCK_PI_LIST32 | FUTEX_PRIVATE_FLAG)

-#define FUTEX_UNLOCK_WAKE_LIST64 (FUTEX_WAKE | FUTEX_UNLOCK_ROBUST)
+#define FUTEX_UNLOCK_WAKE_LIST64 (FUTEX_WAKE | FUTEX_ROBUST_UNLOCK)
#define FUTEX_UNLOCK_WAKE_LIST64_PRIVATE (FUTEX_UNLOCK_WAKE_LIST64 | FUTEX_PRIVATE_FLAG)

-#define FUTEX_UNLOCK_WAKE_LIST32 (FUTEX_WAKE | FUTEX_UNLOCK_ROBUST | \
+#define FUTEX_UNLOCK_WAKE_LIST32 (FUTEX_WAKE | FUTEX_ROBUST_UNLOCK | \
FUTEX_ROBUST_LIST32)
#define FUTEX_UNLOCK_WAKE_LIST32_PRIVATE (FUTEX_UNLOCK_WAKE_LIST32 | FUTEX_PRIVATE_FLAG)

-#define FUTEX_UNLOCK_BITSET_LIST64 (FUTEX_WAKE_BITSET | FUTEX_UNLOCK_ROBUST)
+#define FUTEX_UNLOCK_BITSET_LIST64 (FUTEX_WAKE_BITSET | FUTEX_ROBUST_UNLOCK)
#define FUTEX_UNLOCK_BITSET_LIST64_PRIVATE (FUTEX_UNLOCK_BITSET_LIST64 | FUTEX_PRIVATE_FLAG)

-#define FUTEX_UNLOCK_BITSET_LIST32 (FUTEX_WAKE_BITSET | FUTEX_UNLOCK_ROBUST | \
+#define FUTEX_UNLOCK_BITSET_LIST32 (FUTEX_WAKE_BITSET | FUTEX_ROBUST_UNLOCK | \
FUTEX_ROBUST_LIST32)
#define FUTEX_UNLOCK_BITSET_LIST32_PRIVATE (FUTEX_UNLOCK_BITSET_LIST32 | FUTEX_PRIVATE_FLAG)

--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -40,7 +40,7 @@
#define FLAGS_NUMA 0x0080
#define FLAGS_STRICT 0x0100
#define FLAGS_MPOL 0x0200
-#define FLAGS_UNLOCK_ROBUST 0x0400
+#define FLAGS_ROBUST_UNLOCK 0x0400
#define FLAGS_ROBUST_LIST32 0x0800

/* FUTEX_ to FLAGS_ */
@@ -54,8 +54,8 @@ static inline unsigned int futex_to_flag
if (op & FUTEX_CLOCK_REALTIME)
flags |= FLAGS_CLOCKRT;

- if (op & FUTEX_UNLOCK_ROBUST)
- flags |= FLAGS_UNLOCK_ROBUST;
+ if (op & FUTEX_ROBUST_UNLOCK)
+ flags |= FLAGS_ROBUST_UNLOCK;

if (op & FUTEX_ROBUST_LIST32)
flags |= FLAGS_ROBUST_LIST32;
--- a/kernel/futex/pi.c
+++ b/kernel/futex/pi.c
@@ -1305,7 +1305,7 @@ int futex_unlock_pi(u32 __user *uaddr, u
{
int ret = __futex_unlock_pi(uaddr, flags);

- if (ret || !(flags & FLAGS_UNLOCK_ROBUST))
+ if (ret || !(flags & FLAGS_ROBUST_UNLOCK))
return ret;

if (!futex_robust_list_clear_pending(pop, flags))
--- a/kernel/futex/syscalls.c
+++ b/kernel/futex/syscalls.c
@@ -118,7 +118,7 @@ long do_futex(u32 __user *uaddr, int op,
return -ENOSYS;
}

- if (flags & FLAGS_UNLOCK_ROBUST) {
+ if (flags & FLAGS_ROBUST_UNLOCK) {
if (cmd != FUTEX_WAKE &&
cmd != FUTEX_WAKE_BITSET &&
cmd != FUTEX_UNLOCK_PI)
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -154,7 +154,7 @@ void futex_wake_mark(struct wake_q_head
*/
static bool futex_robust_unlock(u32 __user *uaddr, unsigned int flags, void __user *pop)
{
- if (!(flags & FLAGS_UNLOCK_ROBUST))
+ if (!(flags & FLAGS_ROBUST_UNLOCK))
return true;

/* First unlock the futex, which requires release semantics. */