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Date:   Tue, 20 Dec 2022 10:55:11 +0530
From:   Deepak R Varma <drv@mailo.com>
To:     Russell King <linux@armlinux.org.uk>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     Saurabh Singh Sengar <ssengar@microsoft.com>,
        Praveen Kumar <kumarpraveen@linux.microsoft.com>, drv@mailo.com
Subject: [PATCH] ARM/dma-mapping: use kvzalloc for fallback memory allocation
 need
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When the memory sizes are not known upfront, it is preferred to use the
kvzalloc helper function instead of direct conditional evaluation of
size and kzalloc/vzalloc fallback design. The kvzalloc helper function
in this case is more efficient as it avoids indefinite kzalloc retries
when a small memory size is needed but is unavailable.
This LWN article has further details on the advantages of using
kvzalloc in case of fallback memory allocation needs:
 	https://lwn.net/Articles/711653/

This patch proposal is based on following Coccinelle warning using the
kvmalloc.cocci semantic patch.

arch/arm/mm/dma-mapping.c:858:28-29: WARNING opportunity for kvmalloc

Signed-off-by: Deepak R Varma <drv@mailo.com>
---
Note: The patch proposal is compile tested only.

 arch/arm/mm/dma-mapping.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index c135f6e37a00..2b79af377a81 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -855,10 +855,7 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size,
 	int i = 0;
 	int order_idx = 0;

-	if (array_size <= PAGE_SIZE)
-		pages = kzalloc(array_size, GFP_KERNEL);
-	else
-		pages = vzalloc(array_size);
+	pages = kvzalloc(array_size, GFP_KERNEL);
 	if (!pages)
 		return NULL;

--
2.34.1