From: Matthieu CASTET <matthieu.castet@parrot.com>
Date: Fri, 9 Nov 2012 03:04:19 +0000 (+1100)
Subject: dmapool: make DMAPOOL_DEBUG detect corruption of free marker
X-Git-Tag: next-20121112~5^2~190
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ba748dc82bfbd1d8b6b3a70e8f41a7476a6eb993;p=karo-tx-linux.git

dmapool: make DMAPOOL_DEBUG detect corruption of free marker

This can help to catch the case where hardware is writing after dma free.

Signed-off-by: Matthieu Castet <matthieu.castet@parrot.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/dmapool.c b/mm/dmapool.c
index c5ab33bca0a8..e10898a08ca3 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -346,6 +346,29 @@ 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(int); i < pool->size; i++) {
+			if (data[i] != POOL_POISON_FREED) {
+				if (pool->dev)
+					dev_err(pool->dev,
+							"dma_pool_alloc %s, %p (corruped)\n",
+							pool->name, retval);
+				else
+					printk(KERN_ERR
+							"dma_pool_alloc %s, %p (corruped)\n",
+							pool->name, retval);
+
+				/* we dump the first 4 bytes even if there 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
  done: