Revision 443851200542932414ee63ad774750633a880b4f authored by Linus Torvalds on 02 July 2016, 16:36:49 UTC, committed by Linus Torvalds on 02 July 2016, 16:36:49 UTC
Pull clk fixes from Stephen Boyd: "A small fix for the newly added oxnas clk driver and a handful of rockchip clk driver fixes for newly added rk3399 support" * tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux: clk: Fix return value check in oxnas_stdclk_probe() clk: rockchip: release io resource when failing to init clk on rk3399 clk: rockchip: fix cpuclk registration error handling clk: rockchip: Revert "clk: rockchip: reset init state before mmc card initialization" clk: rockchip: fix incorrect parent for rk3399's {c,g}pll_aclk_perihp_src clk: rockchip: mark rk3399 GIC clocks as critical clk: rockchip: initialize flags of clk_init_data in mmc-phase clock
membarrier.c
/*
* 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>
/*
* 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)
{
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;
}
}
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