To represent the size of a single allocation, dmapool currently uses
'unsigned int' in some places and 'size_t' in other places. Standardize
on 'unsigned int' to reduce overhead, but use 'size_t' when counting all
the blocks in the entire pool.
Signed-off-by: Tony Battersby
---
This was split off from "dmapool: reduce footprint in struct page" in v2.
This puts an upper bound on 'size' of INT_MAX to avoid overflowing the
following comparison in pool_initialize_free_block_list():
unsigned int offset = 0;
unsigned int next = offset + pool->size;
if (unlikely((next + pool->size) > ...
The actual maximum allocation size is probably lower anyway, probably
KMALLOC_MAX_SIZE, but that gets into the implementation details of other
subsystems which don't export a predefined maximum, so I didn't want to
hardcode it here. The purpose of the added bounds check is to avoid
overflowing integers, not to check the actual
(platform/device/config-specific?) maximum allocation size.
'boundary' is passed in as a size_t but gets stored as an unsigned int.
'boundary' values >= 'allocation' do not have any effect, so clipping
'boundary' to 'allocation' keeps it within the range of unsigned int
without affecting anything else. A few lines above (not in the diff)
you can see that if 'boundary' is passed in as 0 then it is set to
'allocation', so it is nothing new. For reference, here is the
relevant code after being patched:
if (!boundary)
boundary = allocation;
else if ((boundary < size) || (boundary & (boundary - 1)))
return NULL;
boundary = min(boundary, allocation);
--- linux/mm/dmapool.c.orig 2018-08-06 17:48:19.0 -0400
+++ linux/mm/dmapool.c 2018-08-06 17:48:54.0 -0400
@@ -57,10 +57,10 @@ struct dma_pool { /* the pool */
#define POOL_MAX_IDX2
struct list_head page_list[POOL_MAX_IDX];
spinlock_t lock;
- size_t size;
+ unsigned int size;
struct device *dev;
- size_t allocation;
- size_t boundary;
+ unsigned int allocation;
+ unsigned int boundary;
char name[32];
struct list_head pools;
};
@@ -86,7 +86,7 @@ show_pools(struct device *dev, struct de
mutex_lock(_lock);
list_for_each_entry(pool, >dma_pools, pools) {
unsigned pages = 0;
- unsigned blocks = 0;
+ size_t blocks = 0;
int list_idx;
spin_lock_irq(>lock);
@@ -103,9 +103,10 @@ show_pools(struct device *dev, struct de
spin_unlock_irq(>lock);
/* per-pool info, no real statistics yet */
- temp = scnprintf(next, size, "%-16s %4u %4zu %4zu %2u\n",
+ temp = scnprintf(next, size, "%-16s %4zu %4zu %4u %2u\n",
pool->name, blocks,
-pages * (pool->allocation / pool->size),
+(size_t) pages *
+(pool->allocation / pool->size),
pool->size, pages);
size -= temp;
next += temp;
@@ -150,7 +151,7 @@ struct dma_pool *dma_pool_create(const c
else if (align & (align - 1))
return NULL;
- if (size == 0)
+ if (size == 0 || size > INT_MAX)
return NULL;
else if (size < 4)
size = 4;
@@ -165,6 +166,8 @@ struct dma_pool *dma_pool_create(const c
else if ((boundary < size) || (boundary & (boundary - 1)))
return NULL;
+ boundary = min(boundary, allocation);
+
retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
if (!retval)
return retval;
@@ -344,7 +347,7 @@ void *dma_pool_alloc(struct dma_pool *po
{
unsigned long flags;
struct page *page;
- size_t offset;
+ unsigned int offset;
void *retval;
void *vaddr;
___
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