[PATCH] futex: fix shared futex operations on nommu

From	Rich Felker <dalias@libc.org>
Newsgroups	linux.kernel
Subject	[PATCH] futex: fix shared futex operations on nommu
Date	2016-04-26 03:10 +0200
Message-ID	<rrZFL-7e1-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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The shared get_futex_key code does not work on nommu, but is not
needed anyway because it's impossible for a given backing to have
multiple distinct virtual addresses on nommu. Simply disable these
code paths by refraining from setting FLAG_SHARED when CONFIG_MMU is
not enabled.

Signed-off-by: Rich Felker <dalias@libc.org>
---
 kernel/futex.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index a5d2e74..ed6f475 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3131,8 +3131,10 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 	int cmd = op & FUTEX_CMD_MASK;
 	unsigned int flags = 0;
 
+#ifdef CONFIG_MMU
 	if (!(op & FUTEX_PRIVATE_FLAG))
 		flags |= FLAGS_SHARED;
+#endif
 
 	if (op & FUTEX_CLOCK_REALTIME) {
 		flags |= FLAGS_CLOCKRT;
-- 
2.8.1

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[PATCH] futex: fix shared futex operations on nommu Rich Felker <dalias@libc.org> - 2016-04-26 03:10 +0200
  Re: [PATCH] futex: fix shared futex operations on nommu Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-04-26 12:00 +0200
    Re: [PATCH] futex: fix shared futex operations on nommu Rich Felker <dalias@libc.org> - 2016-04-26 18:00 +0200
      Re: [PATCH] futex: fix shared futex operations on nommu Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-04-26 18:20 +0200
        Re: [PATCH] futex: fix shared futex operations on nommu Rich Felker <dalias@libc.org> - 2016-04-26 18:30 +0200
          Re: [PATCH] futex: fix shared futex operations on nommu Andrew Morton <akpm@linux-foundation.org> - 2016-04-27 00:30 +0200
            Re: [PATCH] futex: fix shared futex operations on nommu Rich Felker <dalias@libc.org> - 2016-04-27 00:40 +0200
  Re: [PATCH] futex: fix shared futex operations on nommu Thomas Gleixner <tglx@linutronix.de> - 2016-04-27 15:50 +0200

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