linux-kernel - [PATCHv2 10/11] dmapool: don't memset on free twice

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Date:   Fri, 16 Dec 2022 12:16:24 -0800
From:   Keith Busch <kbusch@...a.com>
To:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Matthew Wilcox <willy@...radead.org>
CC:     Tony Battersby <tonyb@...ernetics.com>,
        Kernel Team <kernel-team@...a.com>,
        Keith Busch <kbusch@...nel.org>
Subject: [PATCHv2 10/11] dmapool: don't memset on free twice

From: Keith Busch <kbusch@...nel.org>

If debug is enabled, dmapool will poison the range, so no need to clear
it to 0 immediately before writing over it.

Signed-off-by: Keith Busch <kbusch@...nel.org>
---
 mm/dmapool.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 44622f2bf4641..f5b79c3268856 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -372,10 +372,10 @@ static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 	return NULL;
 }
 
+#ifdef DMAPOOL_DEBUG
 static inline bool pool_page_err(struct dma_pool *pool, struct dma_page *page,
 				 void *vaddr)
 {
-#ifdef DMAPOOL_DEBUG
 	unsigned int chain = page->offset;
 
 	if ((dma - page->dma) != offset) {
@@ -394,9 +394,17 @@ static inline bool pool_page_err(struct dma_pool *pool, struct dma_page *page,
 		return true;
 	}
 	memset(vaddr, POOL_POISON_FREED, pool->size);
-#endif
 	return false;
 }
+#else
+static inline bool pool_page_err(struct dma_pool *pool, struct dma_page *page,
+				 void *vaddr)
+{
+	if (want_init_on_free())
+		memset(vaddr, 0, pool->size);
+	return false;
+}
+#endif
 
 /**
  * dma_pool_free - put block back into dma pool
@@ -423,8 +431,6 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 	}
 
 	offset = vaddr - page->vaddr;
-	if (want_init_on_free())
-		memset(vaddr, 0, pool->size);
 	if (pool_page_err(pool, page, vaddr)) {
 		spin_unlock_irqrestore(&pool->lock, flags);
 		return;
-- 
2.30.2