c633f9e788
In the old times, the whole idle task was considered as an RCU quiescent state. But as RCU became more and more successful overtime, some RCU read side critical section have been added even in the code of some architectures idle tasks, for tracing for example. So nowadays, rcu_idle_enter() and rcu_idle_exit() must be called by the architecture to tell RCU about the part in the idle loop that doesn't make use of rcu read side critical sections, typically the part that puts the CPU in low power mode. This is necessary for RCU to find the quiescent states in idle in order to complete grace periods. Add this missing pair of calls in the Cris's idle loop. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Cris <linux-cris-kernel@axis.com> Cc: <stable@vger.kernel.org> # 3.3+ Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
134 lines
2.8 KiB
C
134 lines
2.8 KiB
C
/*
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* linux/arch/cris/kernel/process.c
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*
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* Copyright (C) 1995 Linus Torvalds
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* Copyright (C) 2000-2002 Axis Communications AB
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*
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* Authors: Bjorn Wesen (bjornw@axis.com)
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*
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*/
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/*
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* This file handles the architecture-dependent parts of process handling..
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*/
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#include <linux/atomic.h>
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#include <asm/pgtable.h>
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#include <asm/uaccess.h>
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#include <asm/irq.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/init_task.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/user.h>
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#include <linux/elfcore.h>
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#include <linux/mqueue.h>
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#include <linux/reboot.h>
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#include <linux/rcupdate.h>
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//#define DEBUG
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/*
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* The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
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* there would ever be a halt sequence (for power save when idle) with
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* some largish delay when halting or resuming *and* a driver that can't
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* afford that delay. The hlt_counter would then be checked before
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* executing the halt sequence, and the driver marks the unhaltable
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* region by enable_hlt/disable_hlt.
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*/
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int cris_hlt_counter=0;
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void disable_hlt(void)
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{
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cris_hlt_counter++;
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}
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EXPORT_SYMBOL(disable_hlt);
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void enable_hlt(void)
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{
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cris_hlt_counter--;
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}
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EXPORT_SYMBOL(enable_hlt);
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/*
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* The following aren't currently used.
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*/
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void (*pm_idle)(void);
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extern void default_idle(void);
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void (*pm_power_off)(void);
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EXPORT_SYMBOL(pm_power_off);
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/*
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* The idle thread. There's no useful work to be
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* done, so just try to conserve power and have a
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* low exit latency (ie sit in a loop waiting for
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* somebody to say that they'd like to reschedule)
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*/
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void cpu_idle (void)
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{
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/* endless idle loop with no priority at all */
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while (1) {
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rcu_idle_enter();
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while (!need_resched()) {
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void (*idle)(void);
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/*
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* Mark this as an RCU critical section so that
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* synchronize_kernel() in the unload path waits
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* for our completion.
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*/
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idle = pm_idle;
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if (!idle)
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idle = default_idle;
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idle();
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}
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rcu_idle_exit();
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schedule_preempt_disabled();
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}
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}
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void hard_reset_now (void);
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void machine_restart(char *cmd)
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{
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hard_reset_now();
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}
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/*
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* Similar to machine_power_off, but don't shut off power. Add code
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* here to freeze the system for e.g. post-mortem debug purpose when
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* possible. This halt has nothing to do with the idle halt.
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*/
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void machine_halt(void)
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{
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}
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/* If or when software power-off is implemented, add code here. */
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void machine_power_off(void)
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{
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}
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/*
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* When a process does an "exec", machine state like FPU and debug
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* registers need to be reset. This is a hook function for that.
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* Currently we don't have any such state to reset, so this is empty.
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*/
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void flush_thread(void)
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{
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}
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/* Fill in the fpu structure for a core dump. */
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int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
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{
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return 0;
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}
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