mirror of https://github.com/schoebel/mars
50 lines
1.0 KiB
C
50 lines
1.0 KiB
C
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// (c) 2010 Thomas Schoebel-Theuer / 1&1 Internet AG
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/semaphore.h>
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#include "lamport.h"
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struct semaphore lamport_sem = __SEMAPHORE_INITIALIZER(lamport_sem, 1); // TODO: replace with spinlock if possible (first check)
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struct timespec lamport_now = {};
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void get_lamport(struct timespec *now)
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{
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int diff;
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down(&lamport_sem);
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*now = CURRENT_TIME;
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diff = timespec_compare(now, &lamport_now);
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if (diff >= 0) {
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timespec_add_ns(now, 1);
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memcpy(&lamport_now, now, sizeof(lamport_now));
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timespec_add_ns(&lamport_now, 1);
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} else {
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timespec_add_ns(&lamport_now, 1);
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memcpy(now, &lamport_now, sizeof(*now));
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}
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up(&lamport_sem);
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}
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EXPORT_SYMBOL_GPL(get_lamport);
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void set_lamport(struct timespec *old)
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{
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int diff;
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down(&lamport_sem);
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diff = timespec_compare(old, &lamport_now);
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if (diff >= 0) {
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memcpy(&lamport_now, old, sizeof(lamport_now));
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timespec_add_ns(&lamport_now, 1);
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}
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up(&lamport_sem);
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}
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EXPORT_SYMBOL_GPL(set_lamport);
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