[tip: locking/urgent] futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI - tip-bot2 for Thomas Gleixner

From: "tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	stable@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org
Subject: [tip: locking/urgent] futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI
Date: Thu, 06 May 2021 18:14:32 -0000	[thread overview]
Message-ID: <162032487280.29796.15925063332304898548.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210422194704.984540159@linutronix.de>

The following commit has been merged into the locking/urgent branch of tip:

Commit-ID:     cdf78db4070967869e4d027c11f4dd825d8f815a
Gitweb:        https://git.kernel.org/tip/cdf78db4070967869e4d027c11f4dd825d8f815a
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Thu, 22 Apr 2021 21:44:19 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 06 May 2021 20:12:40 +02:00

futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI

FUTEX_LOCK_PI does not require to have the FUTEX_CLOCK_REALTIME bit set
because it has been using CLOCK_REALTIME based absolute timeouts
forever. Due to that, the time namespace adjustment which is applied when
FUTEX_CLOCK_REALTIME is not set, will wrongly take place for FUTEX_LOCK_PI
and wreckage the timeout.

Exclude it from that procedure.

Fixes: c2f7d08cccf4 ("futex: Adjust absolute futex timeouts with per time namespace offset")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210422194704.984540159@linutronix.de

---
 kernel/futex.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 4740200..b0f5304 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3780,7 +3780,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
 		t = timespec64_to_ktime(ts);
 		if (cmd == FUTEX_WAIT)
 			t = ktime_add_safe(ktime_get(), t);
-		else if (!(op & FUTEX_CLOCK_REALTIME))
+		else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
 			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
@@ -3974,7 +3974,7 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
 		t = timespec64_to_ktime(ts);
 		if (cmd == FUTEX_WAIT)
 			t = ktime_add_safe(ktime_get(), t);
-		else if (!(op & FUTEX_CLOCK_REALTIME))
+		else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
 			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
