linux-kernel - [PATCH 1/7] futex: abstract out futex_op_to

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Date:   Tue, 11 Jul 2023 18:46:59 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     io-uring@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, peterz@...radead.org,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 1/7] futex: abstract out futex_op_to_flags() helper

Rather than needing to duplicate this for the io_uring hook of futexes,
abstract out a helper.

No functional changes intended in this patch.

Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
 kernel/futex/futex.h    | 15 +++++++++++++++
 kernel/futex/syscalls.c | 11 ++---------
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h
index b5379c0e6d6d..d2949fca37d1 100644
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -291,4 +291,19 @@ extern int futex_unlock_pi(u32 __user *uaddr, unsigned int flags);
 
 extern int futex_lock_pi(u32 __user *uaddr, unsigned int flags, ktime_t *time, int trylock);
 
+static inline bool futex_op_to_flags(int op, int cmd, unsigned int *flags)
+{
+	if (!(op & FUTEX_PRIVATE_FLAG))
+		*flags |= FLAGS_SHARED;
+
+	if (op & FUTEX_CLOCK_REALTIME) {
+		*flags |= FLAGS_CLOCKRT;
+		if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI &&
+		    cmd != FUTEX_LOCK_PI2)
+			return false;
+	}
+
+	return true;
+}
+
 #endif /* _FUTEX_H */
diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c
index a8074079b09e..75ca8c41cc94 100644
--- a/kernel/futex/syscalls.c
+++ b/kernel/futex/syscalls.c
@@ -88,15 +88,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 	int cmd = op & FUTEX_CMD_MASK;
 	unsigned int flags = 0;
 
-	if (!(op & FUTEX_PRIVATE_FLAG))
-		flags |= FLAGS_SHARED;
-
-	if (op & FUTEX_CLOCK_REALTIME) {
-		flags |= FLAGS_CLOCKRT;
-		if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI &&
-		    cmd != FUTEX_LOCK_PI2)
-			return -ENOSYS;
-	}
+	if (!futex_op_to_flags(op, cmd, &flags))
+		return -ENOSYS;
 
 	switch (cmd) {
 	case FUTEX_WAIT:
-- 
2.40.1