Improve lockless buffer allocation by using offsets to extend tag length to avoid ABA issues. This also resolves Bug 1051.
Signed-off-by: Bill Fischofer <[email protected]> --- .../include/odp_buffer_pool_internal.h | 89 ++++++++++++++-------- platform/linux-generic/odp_buffer_pool.c | 7 +- 2 files changed, 59 insertions(+), 37 deletions(-) diff --git a/platform/linux-generic/include/odp_buffer_pool_internal.h b/platform/linux-generic/include/odp_buffer_pool_internal.h index 2e48ac3..169e02d 100644 --- a/platform/linux-generic/include/odp_buffer_pool_internal.h +++ b/platform/linux-generic/include/odp_buffer_pool_internal.h @@ -107,8 +107,8 @@ struct pool_entry_s { size_t pool_size; uint32_t buf_align; uint32_t buf_stride; - _odp_atomic_ptr_t buf_freelist; - _odp_atomic_ptr_t blk_freelist; + odp_atomic_u64_t buf_freelist; + odp_atomic_u64_t blk_freelist; odp_atomic_u32_t bufcount; odp_atomic_u32_t blkcount; odp_atomic_u64_t bufallocs; @@ -142,57 +142,77 @@ extern void *pool_entry_ptr[]; #define pool_is_secure(pool) 0 #endif -#define TAG_ALIGN ((size_t)16) +#define OFFSET_BITS ODP_BITSIZE((uint64_t)ODP_BUFFER_MAX_BUFFERS * \ + (uint32_t)ODP_CONFIG_PACKET_BUF_LEN_MAX) + +#define MAX_OFFSET (1ULL << BUF_OFFSET_BITS) +#define TAG_BITS (64 - OFFSET_BITS) +#define TAG_ALIGN (1ULL << TAG_BITS) + +#define NULL_OFFSET (~0ULL) +#define NULL_DETAGGED_OFFSET ((~0ULL) >> TAG_BITS) #define odp_cs(ptr, old, new) \ - _odp_atomic_ptr_cmp_xchg_strong(&ptr, (void **)&old, (void *)new, \ - _ODP_MEMMODEL_SC, \ - _ODP_MEMMODEL_SC) + _odp_atomic_u64_cmp_xchg_strong_mm(&ptr, (uint64_t *)&old, \ + (uint64_t)new, \ + _ODP_MEMMODEL_SC, _ODP_MEMMODEL_SC) + +/* Helper functions for offset tagging to avoid ABA race conditions */ +#define odp_tag(offset) \ + (((uint64_t)offset) & (TAG_ALIGN - 1)) -/* Helper functions for pointer tagging to avoid ABA race conditions */ -#define odp_tag(ptr) \ - (((size_t)ptr) & (TAG_ALIGN - 1)) +#define off2ptr(offset, base) \ + ((void *)((size_t)base + ((size_t)((uint64_t)offset >> TAG_BITS)))) -#define odp_detag(ptr) \ - ((void *)(((size_t)ptr) & -TAG_ALIGN)) +#define odp_detag(offset, base) \ + (((uint64_t)offset >> TAG_BITS) == NULL_DETAGGED_OFFSET ? NULL : \ + off2ptr(offset, base)) -#define odp_retag(ptr, tag) \ - ((void *)(((size_t)ptr) | odp_tag(tag))) +#define ptr2off(ptr, base) \ + ((uint64_t)(ptr == NULL ? (NULL_DETAGGED_OFFSET << TAG_BITS) : \ + (((uint64_t)((size_t)ptr - (size_t)base)) << TAG_BITS))) + +#define odp_retag(ptr, base, tag) (ptr2off(ptr, base) | odp_tag(tag)) static inline void *get_blk(struct pool_entry_s *pool) { - void *oldhead, *myhead, *newhead; + uint64_t oldhead, newhead; + void *myhead; - oldhead = _odp_atomic_ptr_load(&pool->blk_freelist, _ODP_MEMMODEL_ACQ); + oldhead = odp_atomic_load_u64(&pool->blk_freelist); do { - size_t tag = odp_tag(oldhead); - myhead = odp_detag(oldhead); + uint64_t tag = odp_tag(oldhead); + myhead = odp_detag(oldhead, pool->pool_base_addr); if (odp_unlikely(myhead == NULL)) break; - newhead = odp_retag(((odp_buf_blk_t *)myhead)->next, tag + 1); + newhead = odp_retag(((odp_buf_blk_t *)myhead)->next, + pool->pool_base_addr, tag + 1); } while (odp_cs(pool->blk_freelist, oldhead, newhead) == 0); - if (odp_unlikely(myhead == NULL)) + if (odp_unlikely(myhead == NULL)) { odp_atomic_inc_u64(&pool->blkempty); - else + } else { + odp_atomic_inc_u64(&pool->blkallocs); odp_atomic_dec_u32(&pool->blkcount); + } - return (void *)myhead; + return myhead; } static inline void ret_blk(struct pool_entry_s *pool, void *block) { - void *oldhead, *myhead, *myblock; + uint64_t oldhead, myblock; + void *myhead; - oldhead = _odp_atomic_ptr_load(&pool->blk_freelist, _ODP_MEMMODEL_ACQ); + oldhead = odp_atomic_load_u64(&pool->blk_freelist); do { size_t tag = odp_tag(oldhead); - myhead = odp_detag(oldhead); + myhead = odp_detag(oldhead, pool->pool_base_addr); ((odp_buf_blk_t *)block)->next = myhead; - myblock = odp_retag(block, tag + 1); + myblock = odp_retag(block, pool->pool_base_addr, tag + 1); } while (odp_cs(pool->blk_freelist, oldhead, myblock) == 0); odp_atomic_inc_u32(&pool->blkcount); @@ -201,16 +221,18 @@ static inline void ret_blk(struct pool_entry_s *pool, void *block) static inline odp_buffer_hdr_t *get_buf(struct pool_entry_s *pool) { - odp_buffer_hdr_t *oldhead, *myhead, *newhead; + uint64_t oldhead, newhead; + odp_buffer_hdr_t *myhead; - oldhead = _odp_atomic_ptr_load(&pool->buf_freelist, _ODP_MEMMODEL_ACQ); + oldhead = odp_atomic_load_u64(&pool->buf_freelist); do { size_t tag = odp_tag(oldhead); - myhead = odp_detag(oldhead); + myhead = odp_detag(oldhead, pool->pool_mdata_addr); if (odp_unlikely(myhead == NULL)) break; - newhead = odp_retag(myhead->next, tag + 1); + newhead = odp_retag(myhead->next, pool->pool_mdata_addr, + tag + 1); } while (odp_cs(pool->buf_freelist, oldhead, newhead) == 0); if (odp_unlikely(myhead == NULL)) { @@ -235,7 +257,8 @@ static inline odp_buffer_hdr_t *get_buf(struct pool_entry_s *pool) static inline void ret_buf(struct pool_entry_s *pool, odp_buffer_hdr_t *buf) { - odp_buffer_hdr_t *oldhead, *myhead, *mybuf; + uint64_t oldhead, mybuf; + odp_buffer_hdr_t *myhead; buf->allocator = ODP_FREEBUF; /* Mark buffer free */ @@ -249,13 +272,13 @@ static inline void ret_buf(struct pool_entry_s *pool, odp_buffer_hdr_t *buf) buf->size = 0; } - oldhead = _odp_atomic_ptr_load(&pool->buf_freelist, _ODP_MEMMODEL_ACQ); + oldhead = odp_atomic_load_u64(&pool->buf_freelist); do { size_t tag = odp_tag(oldhead); - myhead = odp_detag(oldhead); + myhead = odp_detag(oldhead, pool->pool_mdata_addr); buf->next = myhead; - mybuf = odp_retag(buf, tag + 1); + mybuf = odp_retag(buf, pool->pool_mdata_addr, tag + 1); } while (odp_cs(pool->buf_freelist, oldhead, mybuf) == 0); uint64_t bufcount = odp_atomic_fetch_add_u32(&pool->bufcount, 1) + 1; diff --git a/platform/linux-generic/odp_buffer_pool.c b/platform/linux-generic/odp_buffer_pool.c index eedb380..5d181bb 100644 --- a/platform/linux-generic/odp_buffer_pool.c +++ b/platform/linux-generic/odp_buffer_pool.c @@ -286,10 +286,9 @@ odp_buffer_pool_t odp_buffer_pool_create(const char *name, pool->s.pool_mdata_addr = mdata_base_addr; pool->s.buf_stride = buf_stride; - _odp_atomic_ptr_store(&pool->s.buf_freelist, NULL, - _ODP_MEMMODEL_RLX); - _odp_atomic_ptr_store(&pool->s.blk_freelist, NULL, - _ODP_MEMMODEL_RLX); + + odp_atomic_store_u64(&pool->s.buf_freelist, NULL_OFFSET); + odp_atomic_store_u64(&pool->s.blk_freelist, NULL_OFFSET); /* Initialization will increment these to their target vals */ odp_atomic_store_u32(&pool->s.bufcount, 0); -- 2.1.0 _______________________________________________ lng-odp mailing list [email protected] http://lists.linaro.org/mailman/listinfo/lng-odp
