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e79e0881cd
Although accesses to ram_list.dirty_memory[] use atomics so multiple threads can safely dirty the bitmap, the data structure is not fully thread-safe yet. This patch handles the RAM hotplug case where ram_list.dirty_memory[] is grown. ram_list.dirty_memory[] is change from a regular bitmap to an RCU array of pointers to fixed-size bitmap blocks. Threads can continue accessing bitmap blocks while the array is being extended. See the comments in the code for an in-depth explanation of struct DirtyMemoryBlocks. I have tested that live migration with virtio-blk dataplane works. Backports commit 5b82b703b69acc67b78b98a5efc897a3912719eb from qemu
81 lines
2.4 KiB
C
81 lines
2.4 KiB
C
/*
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* Bitmap Module
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*
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* Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
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*
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* Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*/
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#ifndef BITMAP_H
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#define BITMAP_H
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#include "glib_compat.h"
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#include <string.h>
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#include <stdlib.h>
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#include "qemu/osdep.h"
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#include "qemu/bitops.h"
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/*
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* The available bitmap operations and their rough meaning in the
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* case that the bitmap is a single unsigned long are thus:
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*
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* Note that nbits should be always a compile time evaluable constant.
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* Otherwise many inlines will generate horrible code.
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*
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* bitmap_set(dst, pos, nbits) Set specified bit area
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* bitmap_set_atomic(dst, pos, nbits) Set specified bit area with atomic ops
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* bitmap_clear(dst, pos, nbits) Clear specified bit area
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* bitmap_test_and_clear_atomic(dst, pos, nbits) Test and clear area
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*/
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/*
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* Also the following operations apply to bitmaps.
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*
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* set_bit(bit, addr) *addr |= bit
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* clear_bit(bit, addr) *addr &= ~bit
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*/
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#define BITMAP_LAST_WORD_MASK(nbits) \
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( \
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((nbits) % BITS_PER_LONG) ? \
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(1UL<<((nbits) % BITS_PER_LONG))-1 : ~0UL \
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)
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#define DECLARE_BITMAP(name,bits) \
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unsigned long name[BITS_TO_LONGS(bits)]
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static inline unsigned long *bitmap_try_new(long nbits)
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{
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long len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
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return g_try_malloc0(len);
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}
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static inline unsigned long *bitmap_new(long nbits)
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{
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unsigned long *ptr = bitmap_try_new(nbits);
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if (ptr == NULL) {
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abort();
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}
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return ptr;
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}
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void bitmap_set(unsigned long *map, long i, long len);
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void bitmap_set_atomic(unsigned long *map, long i, long len);
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void bitmap_clear(unsigned long *map, long start, long nr);
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bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr);
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static inline unsigned long *bitmap_zero_extend(unsigned long *old,
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long old_nbits, long new_nbits)
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{
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long new_len = BITS_TO_LONGS(new_nbits) * sizeof(unsigned long);
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unsigned long *new = g_realloc(old, new_len);
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bitmap_clear(new, old_nbits, new_nbits - old_nbits);
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return new;
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}
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#endif /* BITMAP_H */
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