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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>
93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
/*
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* linux/arch/m68knommu/kernel/time.c
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*
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* Copyright (C) 1991, 1992, 1995 Linus Torvalds
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*
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* This file contains the m68k-specific time handling details.
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* Most of the stuff is located in the machine specific files.
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*
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* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
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* "A Kernel Model for Precision Timekeeping" by Dave Mills
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*/
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#include <linux/errno.h>
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#include <linux/module.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/mm.h>
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#include <linux/profile.h>
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#include <linux/time.h>
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#include <linux/timex.h>
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#include <asm/machdep.h>
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#include <asm/irq_regs.h>
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#define TICK_SIZE (tick_nsec / 1000)
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static inline int set_rtc_mmss(unsigned long nowtime)
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{
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if (mach_set_clock_mmss)
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return mach_set_clock_mmss (nowtime);
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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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irqreturn_t arch_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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if (current->pid)
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profile_tick(CPU_PROFILING);
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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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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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write_sequnlock(&xtime_lock);
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#ifndef CONFIG_SMP
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update_process_times(user_mode(get_irq_regs()));
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#endif
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return(IRQ_HANDLED);
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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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if (mach_gettod)
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mach_gettod(&year, &mon, &day, &hour, &min, &sec);
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else
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year = mon = day = hour = min = sec = 0;
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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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wall_to_monotonic.tv_sec = -xtime.tv_sec;
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hw_timer_init();
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}
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