linux-kernel - [patch 3/6] futex: Get rid of the val2 conditional dance

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Date:   Thu, 22 Apr 2021 21:44:20 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Adhemerval Zanella <adhemerval.zanella@...aro.org>,
        Lukasz Majewski <lukma@...x.de>,
        Florian Weimer <fweimer@...hat.com>,
        Carlos O'Donell <carlos@...hat.com>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Ingo Molnar <mingo@...nel.org>,
        Darren Hart <dvhart@...radead.org>,
        Andrei Vagin <avagin@...il.com>,
        Kurt Kanzenbach <kurt@...utronix.de>
Subject: [patch 3/6] futex: Get rid of the val2 conditional dance

There is no point in checking which FUTEX operand treats the utime pointer
as 'val2' argument because that argument to do_futex() is only used by
exactly these operands.

So just handing it in unconditionally is not making any difference, but
removes a lot of pointless gunk.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/futex.c |   16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3765,7 +3765,6 @@ SYSCALL_DEFINE6(futex, u32 __user *, uad
 {
 	struct timespec64 ts;
 	ktime_t t, *tp = NULL;
-	u32 val2 = 0;
 	int cmd = op & FUTEX_CMD_MASK;
 
 	if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
@@ -3785,15 +3784,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uad
 			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
-	/*
-	 * requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*.
-	 * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP.
-	 */
-	if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
-	    cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
-		val2 = (u32) (unsigned long) utime;
 
-	return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
+	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
 }
 
 #ifdef CONFIG_COMPAT
@@ -3961,7 +3953,6 @@ SYSCALL_DEFINE6(futex_time32, u32 __user
 {
 	struct timespec64 ts;
 	ktime_t t, *tp = NULL;
-	int val2 = 0;
 	int cmd = op & FUTEX_CMD_MASK;
 
 	if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
@@ -3979,11 +3970,8 @@ SYSCALL_DEFINE6(futex_time32, u32 __user
 			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
-	if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
-	    cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
-		val2 = (int) (unsigned long) utime;
 
-	return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
+	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
 }
 #endif /* CONFIG_COMPAT_32BIT_TIME */