From 5de55b265a13bc263c823bbe05d87d2c5e785f6f Mon Sep 17 00:00:00 2001 From: Matthieu CASTET Date: Tue, 11 Dec 2012 16:01:31 -0800 Subject: [PATCH] dmapool: make DMAPOOL_DEBUG detect corruption of free marker This can help to catch the case where hardware is writing after dma free. [akpm@linux-foundation.org: tidy code, fix comment, use sizeof(page->offset), use pr_err()] Signed-off-by: Matthieu Castet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/dmapool.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/mm/dmapool.c b/mm/dmapool.c index da1b0f0b8709..c69781e97cf9 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -332,6 +332,30 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, retval = offset + page->vaddr; *handle = offset + page->dma; #ifdef DMAPOOL_DEBUG + { + int i; + u8 *data = retval; + /* page->offset is stored in first 4 bytes */ + for (i = sizeof(page->offset); i < pool->size; i++) { + if (data[i] == POOL_POISON_FREED) + continue; + if (pool->dev) + dev_err(pool->dev, + "dma_pool_alloc %s, %p (corruped)\n", + pool->name, retval); + else + pr_err("dma_pool_alloc %s, %p (corruped)\n", + pool->name, retval); + + /* + * Dump the first 4 bytes even if they are not + * POOL_POISON_FREED + */ + print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1, + data, pool->size, 1); + break; + } + } memset(retval, POOL_POISON_ALLOCATED, pool->size); #endif spin_unlock_irqrestore(&pool->lock, flags); -- 2.30.2