linux-kernel - [PATCHv2 09/11] dmapool: simplify freeing

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Date:   Fri, 16 Dec 2022 12:16:23 -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 09/11] dmapool: simplify freeing

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

The actions for busy and not busy are mostly the same, so combine these
and remove the unnecessary function. Also, the pool is about to be freed
so there's no need to poison the page data since we only check for
poison on alloc, which can't be done on a freed pool.

Signed-off-by: Keith Busch <kbusch@...nel.org>
---
 mm/dmapool.c | 29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 33d20ceff18c5..44622f2bf4641 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -241,18 +241,6 @@ static inline bool is_page_busy(struct dma_page *page)
 	return page->in_use != 0;
 }
 
-static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
-{
-	dma_addr_t dma = page->dma;
-
-#ifdef	DMAPOOL_DEBUG
-	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
-#endif
-	dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
-	list_del(&page->page_list);
-	kfree(page);
-}
-
 /**
  * dma_pool_destroy - destroys a pool of dma memory blocks.
  * @pool: dma pool that will be destroyed
@@ -280,14 +268,14 @@ void dma_pool_destroy(struct dma_pool *pool)
 	mutex_unlock(&pools_reg_lock);
 
 	list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
-		if (is_page_busy(page)) {
+		if (!is_page_busy(page))
+			dma_free_coherent(pool->dev, pool->allocation,
+					  page->vaddr, page->dma);
+		else
 			dev_err(pool->dev, "%s %s, %p busy\n", __func__,
 				pool->name, page->vaddr);
-			/* leak the still-in-use consistent memory */
-			list_del(&page->page_list);
-			kfree(page);
-		} else
-			pool_free_page(pool, page);
+		list_del(&page->page_list);
+		kfree(page);
 	}
 
 	kfree(pool);
@@ -445,11 +433,6 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 	page->in_use--;
 	*(int *)vaddr = page->offset;
 	page->offset = offset;
-	/*
-	 * Resist a temptation to do
-	 *    if (!is_page_busy(page)) pool_free_page(pool, page);
-	 * Better have a few empty pages hang around.
-	 */
 	spin_unlock_irqrestore(&pool->lock, flags);
 }
 EXPORT_SYMBOL(dma_pool_free);
-- 
2.30.2