linux-kernel - [PATCH v3 2/3] dmapool: Use pool_find_block() in pool_block

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Message-Id: <20241122211144.4186080-2-bjohannesmeyer@gmail.com>
Date: Fri, 22 Nov 2024 22:11:42 +0100
From: Brian Johannesmeyer <bjohannesmeyer@...il.com>
To: Keith Busch <kbusch@...nel.org>,
	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Cc: Brian Johannesmeyer <bjohannesmeyer@...il.com>,
	Raphael Isemann <teemperor@...il.com>,
	Cristiano Giuffrida <giuffrida@...vu.nl>,
	Herbert Bos <h.j.bos@...nl>,
	Greg KH <gregkh@...uxfoundation.org>
Subject: [PATCH v3 2/3] dmapool: Use pool_find_block() in pool_block_err()

In the previous patch, the `pool_find_block()` function was added to
translate a virtual address into the corresponding `struct dma_block`. The
existing `pool_find_page()` function performs a similar role by translating
a DMA address into the `struct dma_page` containing it.

To reduce redundant code and improve consistency, remove the
`pool_find_page()` function and update `pool_block_err()` to use
`pool_find_block()` instead. Doing so eliminates duplicate functionality
and consolidates the block lookup process.

Co-developed-by: Raphael Isemann <teemperor@...il.com>
Signed-off-by: Raphael Isemann <teemperor@...il.com>
Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@...il.com>
---
 mm/dmapool.c | 38 ++++++++++++--------------------------
 1 file changed, 12 insertions(+), 26 deletions(-)

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 3790ca4a631d..f2b96be25412 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -141,39 +141,25 @@ static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
 		memset(block->vaddr, POOL_POISON_ALLOCATED, pool->size);
 }
 
-static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
-{
-	struct dma_page *page;
-
-	list_for_each_entry(page, &pool->page_list, page_list) {
-		if (dma < page->dma)
-			continue;
-		if ((dma - page->dma) < pool->allocation)
-			return page;
-	}
-	return NULL;
-}
-
 static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 {
-	struct dma_block *block = pool->next_block;
-	struct dma_page *page;
+	struct dma_block *block = pool_find_block(pool, vaddr);
 
-	page = pool_find_page(pool, dma);
-	if (!page) {
-		dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
-			__func__, pool->name, vaddr, &dma);
+	if (!block) {
+		dev_err(pool->dev, "%s %s, invalid block %p\n",
+			__func__, pool->name, vaddr);
 		return true;
 	}
 
-	while (block) {
-		if (block->vaddr != vaddr) {
-			block = block->next_block;
-			continue;
+	struct dma_block *iter = pool->next_block;
+
+	while (iter) {
+		if (iter == block) {
+			dev_err(pool->dev, "%s %s, dma %pad already free\n",
+				__func__, pool->name, &dma);
+			return true;
 		}
-		dev_err(pool->dev, "%s %s, dma %pad already free\n",
-			__func__, pool->name, &dma);
-		return true;
+		iter = iter->next_block;
 	}
 
 	memset(vaddr, POOL_POISON_FREED, pool->size);
-- 
2.34.1