From: Matthieu CASTET <matthieu.castet@parrot.com>
Date: Wed, 12 Dec 2012 00:01:31 +0000 (-0800)
Subject: dmapool: make DMAPOOL_DEBUG detect corruption of free marker
X-Git-Tag: firefly_0821_release~3680^2~1516^2~38
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5de55b265a13bc263c823bbe05d87d2c5e785f6f;p=firefly-linux-kernel-4.4.55.git

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 <matthieu.castet@parrot.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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);