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Fix a race in rtree_szind_slab_update() for RTREE_LEAF_COMPACT.

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This commit is contained in:
Jason Evans 2017-03-27 04:08:51 -07:00
parent 7c00f04ff4
commit 4020523f67
2 changed files with 53 additions and 13 deletions
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1
include/jemalloc/internal/private_symbols.txt
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@ -439,6 +439,7 @@ rtree_leaf_elm_release
rtree_leaf_elm_slab_read
rtree_leaf_elm_slab_write
rtree_leaf_elm_szind_read
rtree_leaf_elm_szind_slab_update
rtree_leaf_elm_szind_write
rtree_leaf_elm_witness_access
rtree_leaf_elm_witness_acquire

65
include/jemalloc/internal/rtree_inlines.h
View File

@ -26,6 +26,8 @@ void rtree_leaf_elm_slab_write(tsdn_t *tsdn, rtree_t *rtree,
rtree_leaf_elm_t *elm, bool acquired, bool slab);
void rtree_leaf_elm_write(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm,
bool acquired, extent_t *extent, szind_t szind, bool slab);
void rtree_leaf_elm_szind_slab_update(tsdn_t *tsdn, rtree_t *rtree,
rtree_leaf_elm_t *elm, szind_t szind, bool slab);
rtree_leaf_elm_t *rtree_leaf_elm_lookup(tsdn_t *tsdn, rtree_t *rtree,
rtree_ctx_t *rtree_ctx, uintptr_t key, bool dependent, bool init_missing);
bool rtree_write(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
@ -41,12 +43,12 @@ bool rtree_extent_szind_read(tsdn_t *tsdn, rtree_t *rtree,
szind_t *r_szind);
bool rtree_szind_slab_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, bool dependent, szind_t *r_szind, bool *r_slab);
void rtree_szind_slab_update(tsdn_t *tsdn, rtree_t *rtree,
rtree_ctx_t *rtree_ctx, uintptr_t key, szind_t szind, bool slab);
rtree_leaf_elm_t *rtree_leaf_elm_acquire(tsdn_t *tsdn, rtree_t *rtree,
rtree_ctx_t *rtree_ctx, uintptr_t key, bool dependent, bool init_missing);
void rtree_leaf_elm_release(tsdn_t *tsdn, rtree_t *rtree,
rtree_leaf_elm_t *elm);
void rtree_szind_slab_update(tsdn_t *tsdn, rtree_t *rtree,
rtree_ctx_t *rtree_ctx, uintptr_t key, szind_t szind, bool slab);
void rtree_clear(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key);
#endif
@ -251,12 +253,12 @@ rtree_leaf_elm_slab_write(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm,
JEMALLOC_INLINE void
rtree_leaf_elm_write(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm,
bool acquired, extent_t *extent, szind_t szind, bool slab) {
#ifdef RTREE_LEAF_COMPACT
if (config_debug && acquired) {
rtree_leaf_elm_witness_access(tsdn, rtree, elm);
}
assert(!slab || szind < NBINS);
#ifdef RTREE_LEAF_COMPACT
uintptr_t bits = ((uintptr_t)szind << LG_VADDR) |
((uintptr_t)extent & (((uintptr_t)0x1 << LG_VADDR) - 1)) |
((uintptr_t)slab << 1) |
@ -274,6 +276,44 @@ rtree_leaf_elm_write(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm,
#endif
}
JEMALLOC_INLINE void
rtree_leaf_elm_szind_slab_update(tsdn_t *tsdn, rtree_t *rtree,
rtree_leaf_elm_t *elm, szind_t szind, bool slab) {
assert(!slab || szind < NBINS);
/*
* The caller implicitly assures that it is the only writer to the szind
* and slab fields, and that the extent field cannot currently change.
*/
#ifdef RTREE_LEAF_COMPACT
/*
* Another thread may concurrently acquire the elm, which means that
* even though the szind and slab fields will not be concurrently
* modified by another thread, the fact that the lock is embedded in the
* same word requires that a CAS operation be used here.
*/
uintptr_t old_bits = rtree_leaf_elm_bits_read(tsdn, rtree, elm, false,
true) & ~((uintptr_t)0x1); /* Mask lock bit. */
uintptr_t bits = ((uintptr_t)szind << LG_VADDR) |
((uintptr_t)rtree_leaf_elm_bits_extent_get(old_bits) &
(((uintptr_t)0x1 << LG_VADDR) - 1)) |
((uintptr_t)slab << 1);
spin_t spinner = SPIN_INITIALIZER;
while (true) {
if (likely(atomic_compare_exchange_strong_p(&elm->le_bits,
(void **)&old_bits, (void *)bits, ATOMIC_ACQUIRE,
ATOMIC_RELAXED))) {
break;
}
spin_adaptive(&spinner);
}
#else
/* No need to lock. */
rtree_leaf_elm_slab_write(tsdn, rtree, elm, false, slab);
rtree_leaf_elm_szind_write(tsdn, rtree, elm, false, szind);
#endif
}
JEMALLOC_ALWAYS_INLINE rtree_leaf_elm_t *
rtree_leaf_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, bool dependent, bool init_missing) {
@ -404,16 +444,6 @@ rtree_szind_slab_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
return false;
}
JEMALLOC_INLINE void
rtree_szind_slab_update(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, szind_t szind, bool slab) {
assert(!slab || szind < NBINS);
rtree_leaf_elm_t *elm = rtree_read(tsdn, rtree, rtree_ctx, key, true);
rtree_leaf_elm_slab_write(tsdn, rtree, elm, false, slab);
rtree_leaf_elm_szind_write(tsdn, rtree, elm, false, szind);
}
JEMALLOC_INLINE rtree_leaf_elm_t *
rtree_leaf_elm_acquire(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, bool dependent, bool init_missing) {
@ -464,6 +494,15 @@ rtree_leaf_elm_release(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm) {
}
}
JEMALLOC_INLINE void
rtree_szind_slab_update(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, szind_t szind, bool slab) {
assert(!slab || szind < NBINS);
rtree_leaf_elm_t *elm = rtree_read(tsdn, rtree, rtree_ctx, key, true);
rtree_leaf_elm_szind_slab_update(tsdn, rtree, elm, szind, slab);
}
JEMALLOC_INLINE void
rtree_clear(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key) {