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Fix chunk_alloc_dss() regression.

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Fix chunk_alloc_dss() to account for bytes that are not a multiple of
the chunk size.  This regression was introduced by
e2bcf037d445a84a71c7997670819ebd0a893b4a (Make dss operations
lockless.), which was first released in 4.3.0.
This commit is contained in:
Jason Evans 2017-02-24 09:45:33 -08:00
parent 08c24e7c1a
commit adae7cfc4a
1 changed files with 27 additions and 18 deletions
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45
src/chunk_dss.c
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@ -115,8 +115,9 @@ chunk_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
* malloc. * malloc.
*/ */
while (true) { while (true) {
void *ret, *cpad, *max_cur, *dss_next, *dss_prev; void *ret, *max_cur, *dss_next, *dss_prev;
size_t gap_size, cpad_size; void *gap_addr_chunk, *gap_addr_subchunk;
size_t gap_size_chunk, gap_size_subchunk;
intptr_t incr; intptr_t incr;
max_cur = chunk_dss_max_update(new_addr); max_cur = chunk_dss_max_update(new_addr);
@ -124,25 +125,32 @@ chunk_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
goto label_oom; goto label_oom;
/* /*
* Calculate how much padding is necessary to * Compute how much chunk-aligned gap space (if any) is
* chunk-align the end of the DSS.
*/
gap_size = (chunksize - CHUNK_ADDR2OFFSET(dss_max)) &
chunksize_mask;
/*
* Compute how much chunk-aligned pad space (if any) is
* necessary to satisfy alignment. This space can be * necessary to satisfy alignment. This space can be
* recycled for later use. * recycled for later use.
*/ */
cpad = (void *)((uintptr_t)dss_max + gap_size); gap_addr_chunk = (void *)(CHUNK_CEILING(
ret = (void *)ALIGNMENT_CEILING((uintptr_t)dss_max, (uintptr_t)max_cur));
alignment); ret = (void *)ALIGNMENT_CEILING(
cpad_size = (uintptr_t)ret - (uintptr_t)cpad; (uintptr_t)gap_addr_chunk, alignment);
gap_size_chunk = (uintptr_t)ret -
(uintptr_t)gap_addr_chunk;
/*
* Compute the address just past the end of the desired
* allocation space.
*/
dss_next = (void *)((uintptr_t)ret + size); dss_next = (void *)((uintptr_t)ret + size);
if ((uintptr_t)ret < (uintptr_t)dss_max || if ((uintptr_t)ret < (uintptr_t)max_cur ||
(uintptr_t)dss_next < (uintptr_t)dss_max) (uintptr_t)dss_next < (uintptr_t)max_cur)
goto label_oom; /* Wrap-around. */ goto label_oom; /* Wrap-around. */
incr = gap_size + cpad_size + size; /* Compute the increment, including subchunk bytes. */
gap_addr_subchunk = max_cur;
gap_size_subchunk = (uintptr_t)ret -
(uintptr_t)gap_addr_subchunk;
incr = gap_size_subchunk + size;
assert((uintptr_t)max_cur + incr == (uintptr_t)ret +
size);
/* /*
* Optimistically update dss_max, and roll back below if * Optimistically update dss_max, and roll back below if
@ -157,11 +165,12 @@ chunk_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
dss_prev = chunk_dss_sbrk(incr); dss_prev = chunk_dss_sbrk(incr);
if (dss_prev == max_cur) { if (dss_prev == max_cur) {
/* Success. */ /* Success. */
if (cpad_size != 0) { if (gap_size_chunk != 0) {
chunk_hooks_t chunk_hooks = chunk_hooks_t chunk_hooks =
CHUNK_HOOKS_INITIALIZER; CHUNK_HOOKS_INITIALIZER;
chunk_dalloc_wrapper(tsdn, arena, chunk_dalloc_wrapper(tsdn, arena,
&chunk_hooks, cpad, cpad_size, &chunk_hooks, gap_addr_chunk,
gap_size_chunk,
arena_extent_sn_next(arena), false, arena_extent_sn_next(arena), false,
true); true);
} }