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anv/allocator: Avoid race condition in anv_block_pool_map.

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Accessing bo->map and then pool->center_bo_offset without a lock is
racy. One way of avoiding such race condition is to store the bo->map +
center_bo_offset into pool->map at the time the block pool is growing,
which happens within a lock.

v2: Only set pool->map if not using softpin (Jason).
v3: Move things around and only update center_bo_offset if not using
softpin too (Jason).

Cc: Jason Ekstrand <jason@jlekstrand.net>
Reported-by: Ian Romanick <idr@freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109442
Fixes: fc3f588320
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This commit is contained in:
Rafael Antognolli 2019-01-23 12:36:39 -08:00
parent c1efa240c9
commit f2ece26601
2 changed files with 27 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
src/intel/vulkan/anv_allocator.c
View file

@ -436,7 +436,9 @@ anv_block_pool_init(struct anv_block_pool *pool,
pool->bo_flags = bo_flags;
pool->nbos = 0;
pool->size = 0;
pool->center_bo_offset = 0;
pool->start_address = gen_canonical_address(start_address);
pool->map = NULL;
/* This pointer will always point to the first BO in the list */
pool->bo = &pool->bos[0];
@ -536,6 +538,7 @@ anv_block_pool_expand_range(struct anv_block_pool *pool,
if (map == MAP_FAILED)
return vk_errorf(pool->device->instance, pool->device,
VK_ERROR_MEMORY_MAP_FAILED, "gem mmap failed: %m");
assert(center_bo_offset == 0);
} else {
/* Just leak the old map until we destroy the pool. We can't munmap it
* without races or imposing locking on the block allocate fast path. On
@ -549,6 +552,11 @@ anv_block_pool_expand_range(struct anv_block_pool *pool,
if (map == MAP_FAILED)
return vk_errorf(pool->device->instance, pool->device,
VK_ERROR_MEMORY_MAP_FAILED, "mmap failed: %m");
/* Now that we mapped the new memory, we can write the new
* center_bo_offset back into pool and update pool->map. */
pool->center_bo_offset = center_bo_offset;
pool->map = map + center_bo_offset;
gem_handle = anv_gem_userptr(pool->device, map, size);
if (gem_handle == 0) {
munmap(map, size);
@ -573,10 +581,6 @@ anv_block_pool_expand_range(struct anv_block_pool *pool,
if (!pool->device->info.has_llc)
anv_gem_set_caching(pool->device, gem_handle, I915_CACHING_CACHED);
/* Now that we successfull allocated everything, we can write the new
* center_bo_offset back into pool. */
pool->center_bo_offset = center_bo_offset;
/* For block pool BOs we have to be a bit careful about where we place them
* in the GTT. There are two documented workarounds for state base address
* placement : Wa32bitGeneralStateOffset and Wa32bitInstructionBaseOffset
@ -670,8 +674,12 @@ anv_block_pool_get_bo(struct anv_block_pool *pool, int32_t *offset)
void*
anv_block_pool_map(struct anv_block_pool *pool, int32_t offset)
{
struct anv_bo *bo = anv_block_pool_get_bo(pool, &offset);
return bo->map + pool->center_bo_offset + offset;
if (pool->bo_flags & EXEC_OBJECT_PINNED) {
struct anv_bo *bo = anv_block_pool_get_bo(pool, &offset);
return bo->map + offset;
} else {
return pool->map + offset;
}
}
/** Grows and re-centers the block pool.

13
src/intel/vulkan/anv_private.h
View file

@ -663,6 +663,19 @@ struct anv_block_pool {
*/
uint32_t center_bo_offset;
/* Current memory map of the block pool. This pointer may or may not
* point to the actual beginning of the block pool memory. If
* anv_block_pool_alloc_back has ever been called, then this pointer
* will point to the "center" position of the buffer and all offsets
* (negative or positive) given out by the block pool alloc functions
* will be valid relative to this pointer.
*
* In particular, map == bo.map + center_offset
*
* DO NOT access this pointer directly. Use anv_block_pool_map() instead,
* since it will handle the softpin case as well, where this points to NULL.
*/
void *map;
int fd;
/**