2024-06-15 21:02:09 +02:00
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright IBM Corp. 2007, 2012
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* Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
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*/
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#include <linux/vmalloc.h>
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#include <linux/bitmap.h>
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#include <linux/bitops.h>
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#include "idset.h"
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#include "css.h"
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struct idset {
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int num_ssid;
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int num_id;
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unsigned long bitmap[];
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};
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2024-03-27 16:23:45 +01:00
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static inline unsigned long idset_bitmap_size(int num_ssid, int num_id)
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{
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bitmap: introduce generic optimized bitmap_size()
commit a37fbe666c016fd89e4460d0ebfcea05baba46dc upstream.
The number of times yet another open coded
`BITS_TO_LONGS(nbits) * sizeof(long)` can be spotted is huge.
Some generic helper is long overdue.
Add one, bitmap_size(), but with one detail.
BITS_TO_LONGS() uses DIV_ROUND_UP(). The latter works well when both
divident and divisor are compile-time constants or when the divisor
is not a pow-of-2. When it is however, the compilers sometimes tend
to generate suboptimal code (GCC 13):
48 83 c0 3f add $0x3f,%rax
48 c1 e8 06 shr $0x6,%rax
48 8d 14 c5 00 00 00 00 lea 0x0(,%rax,8),%rdx
%BITS_PER_LONG is always a pow-2 (either 32 or 64), but GCC still does
full division of `nbits + 63` by it and then multiplication by 8.
Instead of BITS_TO_LONGS(), use ALIGN() and then divide by 8. GCC:
8d 50 3f lea 0x3f(%rax),%edx
c1 ea 03 shr $0x3,%edx
81 e2 f8 ff ff 1f and $0x1ffffff8,%edx
Now it shifts `nbits + 63` by 3 positions (IOW performs fast division
by 8) and then masks bits[2:0]. bloat-o-meter:
add/remove: 0/0 grow/shrink: 20/133 up/down: 156/-773 (-617)
Clang does it better and generates the same code before/after starting
from -O1, except that with the ALIGN() approach it uses %edx and thus
still saves some bytes:
add/remove: 0/0 grow/shrink: 9/133 up/down: 18/-538 (-520)
Note that we can't expand DIV_ROUND_UP() by adding a check and using
this approach there, as it's used in array declarations where
expressions are not allowed.
Add this helper to tools/ as well.
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-27 16:23:49 +01:00
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return bitmap_size(size_mul(num_ssid, num_id));
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}
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static struct idset *idset_new(int num_ssid, int num_id)
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{
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struct idset *set;
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2024-03-27 16:23:45 +01:00
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set = vmalloc(sizeof(struct idset) +
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idset_bitmap_size(num_ssid, num_id));
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if (set) {
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set->num_ssid = num_ssid;
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set->num_id = num_id;
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memset(set->bitmap, 0, idset_bitmap_size(num_ssid, num_id));
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}
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return set;
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}
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void idset_free(struct idset *set)
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{
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vfree(set);
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}
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void idset_fill(struct idset *set)
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{
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2024-03-27 16:23:45 +01:00
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memset(set->bitmap, 0xff,
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idset_bitmap_size(set->num_ssid, set->num_id));
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2024-06-15 21:02:09 +02:00
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}
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static inline void idset_add(struct idset *set, int ssid, int id)
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{
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set_bit(ssid * set->num_id + id, set->bitmap);
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}
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static inline void idset_del(struct idset *set, int ssid, int id)
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{
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clear_bit(ssid * set->num_id + id, set->bitmap);
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}
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static inline int idset_contains(struct idset *set, int ssid, int id)
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{
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return test_bit(ssid * set->num_id + id, set->bitmap);
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}
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struct idset *idset_sch_new(void)
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{
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return idset_new(max_ssid + 1, __MAX_SUBCHANNEL + 1);
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}
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void idset_sch_add(struct idset *set, struct subchannel_id schid)
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{
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idset_add(set, schid.ssid, schid.sch_no);
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}
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void idset_sch_del(struct idset *set, struct subchannel_id schid)
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{
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idset_del(set, schid.ssid, schid.sch_no);
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}
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/* Clear ids starting from @schid up to end of subchannel set. */
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void idset_sch_del_subseq(struct idset *set, struct subchannel_id schid)
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{
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int pos = schid.ssid * set->num_id + schid.sch_no;
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bitmap_clear(set->bitmap, pos, set->num_id - schid.sch_no);
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}
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int idset_sch_contains(struct idset *set, struct subchannel_id schid)
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{
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return idset_contains(set, schid.ssid, schid.sch_no);
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}
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int idset_is_empty(struct idset *set)
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{
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return bitmap_empty(set->bitmap, set->num_ssid * set->num_id);
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}
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void idset_add_set(struct idset *to, struct idset *from)
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{
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int len = min(to->num_ssid * to->num_id, from->num_ssid * from->num_id);
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bitmap_or(to->bitmap, to->bitmap, from->bitmap, len);
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}
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