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authorIngo Molnar <mingo@kernel.org>2017-08-21 09:45:19 +0200
committerIngo Molnar <mingo@kernel.org>2017-08-21 09:45:19 +0200
commit94edf6f3c20c9c8ee301bde04150a91bab4bf32c (patch)
tree4a2af658258cf42fde24c1224e44c3e6a18c2792 /kernel/membarrier.c
parentd5da6457bfadf64ff78f1816ae8329dbbba19513 (diff)
parent656e7c0c0a2e8d899f87fd7f081ea7a711146604 (diff)
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU updates from Paul E. McKenney: - Removal of spin_unlock_wait() - SRCU updates - Torture-test updates - Documentation updates - Miscellaneous fixes - CPU-hotplug fixes - Miscellaneous non-RCU fixes Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/membarrier.c')
-rw-r--r--kernel/membarrier.c70
1 files changed, 0 insertions, 70 deletions
diff --git a/kernel/membarrier.c b/kernel/membarrier.c
deleted file mode 100644
index 9f9284f37f8d..000000000000
--- a/kernel/membarrier.c
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * Copyright (C) 2010, 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * membarrier system call
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- */
-
-#include <linux/syscalls.h>
-#include <linux/membarrier.h>
-#include <linux/tick.h>
-
-/*
- * Bitmask made from a "or" of all commands within enum membarrier_cmd,
- * except MEMBARRIER_CMD_QUERY.
- */
-#define MEMBARRIER_CMD_BITMASK (MEMBARRIER_CMD_SHARED)
-
-/**
- * sys_membarrier - issue memory barriers on a set of threads
- * @cmd: Takes command values defined in enum membarrier_cmd.
- * @flags: Currently needs to be 0. For future extensions.
- *
- * If this system call is not implemented, -ENOSYS is returned. If the
- * command specified does not exist, or if the command argument is invalid,
- * this system call returns -EINVAL. For a given command, with flags argument
- * set to 0, this system call is guaranteed to always return the same value
- * until reboot.
- *
- * All memory accesses performed in program order from each targeted thread
- * is guaranteed to be ordered with respect to sys_membarrier(). If we use
- * the semantic "barrier()" to represent a compiler barrier forcing memory
- * accesses to be performed in program order across the barrier, and
- * smp_mb() to represent explicit memory barriers forcing full memory
- * ordering across the barrier, we have the following ordering table for
- * each pair of barrier(), sys_membarrier() and smp_mb():
- *
- * The pair ordering is detailed as (O: ordered, X: not ordered):
- *
- * barrier() smp_mb() sys_membarrier()
- * barrier() X X O
- * smp_mb() X O O
- * sys_membarrier() O O O
- */
-SYSCALL_DEFINE2(membarrier, int, cmd, int, flags)
-{
- /* MEMBARRIER_CMD_SHARED is not compatible with nohz_full. */
- if (tick_nohz_full_enabled())
- return -ENOSYS;
- if (unlikely(flags))
- return -EINVAL;
- switch (cmd) {
- case MEMBARRIER_CMD_QUERY:
- return MEMBARRIER_CMD_BITMASK;
- case MEMBARRIER_CMD_SHARED:
- if (num_online_cpus() > 1)
- synchronize_sched();
- return 0;
- default:
- return -EINVAL;
- }
-}