aa02cd2d9b
Commit d3d74453c3 ("hrtimer: fixup the
HRTIMER_CB_IRQSAFE_NO_SOFTIRQ fallback") broke several archs, and since
only Russell bothered to merge the fix, and Greg to ACK his arch, I'm
sending this for merger.
I have confirmation that the Alpha bit results in a booting kernel.
That leaves: blackfin, frv, sh and sparc untested.
The deadlock in question was found by Russell:
IRQ handle
-> timer_tick() - xtime seqlock held for write
-> update_process_times()
-> run_local_timers()
-> hrtimer_run_queues()
-> hrtimer_get_softirq_time() - tries to get a read lock
Now, Thomas assures me the fix is trivial, only do_timer() needs to be
done under the xtime_lock, and update_process_times() can savely be
removed from under it.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Greg Ungerer <gerg@uclinux.org>
CC: Richard Henderson <rth@twiddle.net>
CC: Bryan Wu <bryan.wu@analog.com>
CC: David Howells <dhowells@redhat.com>
CC: Paul Mundt <lethal@linux-sh.org>
CC: William Irwin <wli@holomorphy.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
154 lines
4.1 KiB
C
154 lines
4.1 KiB
C
/* time.c: FRV arch-specific time handling
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*
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* Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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* - Derived from arch/m68k/kernel/time.c
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/string.h>
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#include <linux/interrupt.h>
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#include <linux/profile.h>
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#include <linux/irq.h>
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#include <linux/mm.h>
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#include <asm/io.h>
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#include <asm/timer-regs.h>
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#include <asm/mb-regs.h>
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#include <asm/mb86943a.h>
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#include <linux/timex.h>
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#define TICK_SIZE (tick_nsec / 1000)
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unsigned long __nongprelbss __clkin_clock_speed_HZ;
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unsigned long __nongprelbss __ext_bus_clock_speed_HZ;
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unsigned long __nongprelbss __res_bus_clock_speed_HZ;
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unsigned long __nongprelbss __sdram_clock_speed_HZ;
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unsigned long __nongprelbss __core_bus_clock_speed_HZ;
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unsigned long __nongprelbss __core_clock_speed_HZ;
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unsigned long __nongprelbss __dsu_clock_speed_HZ;
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unsigned long __nongprelbss __serial_clock_speed_HZ;
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unsigned long __delay_loops_MHz;
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static irqreturn_t timer_interrupt(int irq, void *dummy);
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static struct irqaction timer_irq = {
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.handler = timer_interrupt,
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.flags = IRQF_DISABLED,
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.mask = CPU_MASK_NONE,
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.name = "timer",
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};
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static inline int set_rtc_mmss(unsigned long nowtime)
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{
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return -1;
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}
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/*
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* timer_interrupt() needs to keep up the real-time clock,
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* as well as call the "do_timer()" routine every clocktick
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*/
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static irqreturn_t timer_interrupt(int irq, void *dummy)
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{
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/* last time the cmos clock got updated */
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static long last_rtc_update = 0;
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profile_tick(CPU_PROFILING);
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/*
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* Here we are in the timer irq handler. We just have irqs locally
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* disabled but we don't know if the timer_bh is running on the other
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* CPU. We need to avoid to SMP race with it. NOTE: we don't need
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* the irq version of write_lock because as just said we have irq
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* locally disabled. -arca
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*/
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write_seqlock(&xtime_lock);
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do_timer(1);
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/*
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* If we have an externally synchronized Linux clock, then update
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* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
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* called as close as possible to 500 ms before the new second starts.
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*/
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if (ntp_synced() &&
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xtime.tv_sec > last_rtc_update + 660 &&
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(xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
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(xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2
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) {
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if (set_rtc_mmss(xtime.tv_sec) == 0)
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last_rtc_update = xtime.tv_sec;
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else
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last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
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}
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#ifdef CONFIG_HEARTBEAT
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static unsigned short n;
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n++;
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__set_LEDS(n);
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#endif /* CONFIG_HEARTBEAT */
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write_sequnlock(&xtime_lock);
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update_process_times(user_mode(get_irq_regs()));
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return IRQ_HANDLED;
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}
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void time_divisor_init(void)
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{
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unsigned short base, pre, prediv;
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/* set the scheduling timer going */
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pre = 1;
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prediv = 4;
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base = __res_bus_clock_speed_HZ / pre / HZ / (1 << prediv);
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__set_TPRV(pre);
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__set_TxCKSL_DATA(0, prediv);
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__set_TCTR(TCTR_SC_CTR0 | TCTR_RL_RW_LH8 | TCTR_MODE_2);
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__set_TCSR_DATA(0, base & 0xff);
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__set_TCSR_DATA(0, base >> 8);
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}
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void time_init(void)
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{
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unsigned int year, mon, day, hour, min, sec;
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extern void arch_gettod(int *year, int *mon, int *day, int *hour, int *min, int *sec);
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/* FIX by dqg : Set to zero for platforms that don't have tod */
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/* without this time is undefined and can overflow time_t, causing */
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/* very strange errors */
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year = 1980;
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mon = day = 1;
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hour = min = sec = 0;
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arch_gettod (&year, &mon, &day, &hour, &min, &sec);
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if ((year += 1900) < 1970)
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year += 100;
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xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
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xtime.tv_nsec = 0;
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/* install scheduling interrupt handler */
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setup_irq(IRQ_CPU_TIMER0, &timer_irq);
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time_divisor_init();
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}
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/*
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* Scheduler clock - returns current time in nanosec units.
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*/
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unsigned long long sched_clock(void)
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{
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return jiffies_64 * (1000000000 / HZ);
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}
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