netdev - [PATCH net-next 5/6] e1000: Remove unnecessary use of kmap

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Message-Id: <20221102203957.2944396-6-anthony.l.nguyen@intel.com>
Date:   Wed,  2 Nov 2022 13:39:56 -0700
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Anirudh Venkataramanan <anirudh.venkataramanan@...el.com>,
        netdev@...r.kernel.org, anthony.l.nguyen@...el.com,
        Ira Weiny <ira.weiny@...el.com>,
        "Fabio M . De Francesco" <fmdefrancesco@...il.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>
Subject: [PATCH net-next 5/6] e1000: Remove unnecessary use of kmap_atomic()

From: Anirudh Venkataramanan <anirudh.venkataramanan@...el.com>

buffer_info->rxbuf.page accessed in e1000_clean_jumbo_rx_irq() is
allocated using GFP_ATOMIC. Pages allocated with GFP_ATOMIC can't come from
highmem and so there's no need to kmap() them. Just use page_address().

I don't have access to a 32-bit system so did some limited testing on
qemu (qemu-system-i386 -m 4096 -smp 4 -device e1000e) with a 32-bit
Debian 11.04 image.

Cc: Ira Weiny <ira.weiny@...el.com>
Cc: Fabio M. De Francesco <fmdefrancesco@...il.com>
Cc: Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>
Suggested-by: Ira Weiny <ira.weiny@...el.com>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@...el.com>
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/e1000/e1000_main.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
index 61e60e4de600..da6e303ad99b 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_main.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
@@ -4229,8 +4229,6 @@ static bool e1000_clean_jumbo_rx_irq(struct e1000_adapter *adapter,
 				 */
 				p = buffer_info->rxbuf.page;
 				if (length <= copybreak) {
-					u8 *vaddr;
-
 					if (likely(!(netdev->features & NETIF_F_RXFCS)))
 						length -= 4;
 					skb = e1000_alloc_rx_skb(adapter,
@@ -4238,10 +4236,9 @@ static bool e1000_clean_jumbo_rx_irq(struct e1000_adapter *adapter,
 					if (!skb)
 						break;
 
-					vaddr = kmap_atomic(p);
-					memcpy(skb_tail_pointer(skb), vaddr,
-					       length);
-					kunmap_atomic(vaddr);
+					memcpy(skb_tail_pointer(skb),
+					       page_address(p), length);
+
 					/* re-use the page, so don't erase
 					 * buffer_info->rxbuf.page
 					 */
-- 
2.35.1