diff mbox series

[v2,net-next,3/6] cassini: Use page_address() instead of kmap_atomic()

Message ID 20221123205219.31748-4-anirudh.venkataramanan@intel.com (mailing list archive)
State Accepted
Commit c191445874bba16a636a88fc4afc7c3ab09228fd
Delegated to: Netdev Maintainers
Headers show
Series Remove uses of kmap_atomic() | expand

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Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 7 this patch: 7
netdev/cc_maintainers warning 5 maintainers not CCed: pabeni@redhat.com edumazet@google.com kuba@kernel.org christophe.jaillet@wanadoo.fr davem@davemloft.net
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
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netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 7 this patch: 7
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Anirudh Venkataramanan Nov. 23, 2022, 8:52 p.m. UTC 
Pages for Rx buffers are allocated in cas_page_alloc() using either
GFP_ATOMIC or GFP_KERNEL. Memory allocated with GFP_KERNEL/GFP_ATOMIC can't
come from highmem and so there's no need to kmap() them. Just use
page_address() instead. This makes the variable 'addr' unnecessary, so
remove it too.

Note that kmap_atomic() disables preemption and page-fault processing,
but page_address() doesn't. When removing uses of kmap_atomic(), one has to
check if the code being executed between the map/unmap implicitly depends
on page-faults and/or preemption being disabled. If yes, then code to
disable page-faults and/or preemption should also be added for functional
correctness. That however doesn't appear to be the case here, so just
page_address() is used.

I don't have hardware, so this change has only been compile tested.

Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
---
v1 -> v2: Update commit message
---
 drivers/net/ethernet/sun/cassini.c | 34 ++++++++++--------------------
 1 file changed, 11 insertions(+), 23 deletions(-)

Comments

Fabio M. De Francesco Nov. 25, 2022, 3:38 p.m. UTC | #1 
On mercoledì 23 novembre 2022 21:52:16 CET Anirudh Venkataramanan wrote:
> Pages for Rx buffers are allocated in cas_page_alloc() using either
> GFP_ATOMIC or GFP_KERNEL. Memory allocated with GFP_KERNEL/GFP_ATOMIC can't
> come from highmem and so there's no need to kmap() them. Just use
> page_address() instead. This makes the variable 'addr' unnecessary, so
> remove it too.
> 
> Note that kmap_atomic() disables preemption and page-fault processing,
> but page_address() doesn't. When removing uses of kmap_atomic(), one has to
> check if the code being executed between the map/unmap implicitly depends
> on page-faults and/or preemption being disabled. If yes, then code to
> disable page-faults and/or preemption should also be added for functional
> correctness. That however doesn't appear to be the case here, so just
> page_address() is used.
> 
> I don't have hardware, so this change has only been compile tested.
> 
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
> ---
> v1 -> v2: Update commit message
> ---
>  drivers/net/ethernet/sun/cassini.c | 34 ++++++++++--------------------
>  1 file changed, 11 insertions(+), 23 deletions(-)

Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>

Thanks,

Fabio

> diff --git a/drivers/net/ethernet/sun/cassini.c
> b/drivers/net/ethernet/sun/cassini.c index 0aca193..2f66cfc 100644
> --- a/drivers/net/ethernet/sun/cassini.c
> +++ b/drivers/net/ethernet/sun/cassini.c
> @@ -1915,7 +1915,7 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, int off, swivel = RX_SWIVEL_OFF_VAL;
>  	struct cas_page *page;
>  	struct sk_buff *skb;
> -	void *addr, *crcaddr;
> +	void *crcaddr;
>  	__sum16 csum;
>  	char *p;
> 
> @@ -1936,7 +1936,7 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, skb_reserve(skb, swivel);
> 
>  	p = skb->data;
> -	addr = crcaddr = NULL;
> +	crcaddr = NULL;
>  	if (hlen) { /* always copy header pages */
>  		i = CAS_VAL(RX_COMP2_HDR_INDEX, words[1]);
>  		page = cp->rx_pages[CAS_VAL(RX_INDEX_RING, i)]
[CAS_VAL(RX_INDEX_NUM, i)];
> @@ -1948,12 +1948,10 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, i += cp->crc_size;
>  		dma_sync_single_for_cpu(&cp->pdev->dev, page->dma_addr + 
off,
>  					i, DMA_FROM_DEVICE);
> -		addr = cas_page_map(page->buffer);
> -		memcpy(p, addr + off, i);
> +		memcpy(p, page_address(page->buffer) + off, i);
>  		dma_sync_single_for_device(&cp->pdev->dev,
>  					   page->dma_addr + off, i,
>  					   DMA_FROM_DEVICE);
> -		cas_page_unmap(addr);
>  		RX_USED_ADD(page, 0x100);
>  		p += hlen;
>  		swivel = 0;
> @@ -1984,12 +1982,11 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, /* make sure we always copy a header */
>  		swivel = 0;
>  		if (p == (char *) skb->data) { /* not split */
> -			addr = cas_page_map(page->buffer);
> -			memcpy(p, addr + off, RX_COPY_MIN);
> +			memcpy(p, page_address(page->buffer) + off,
> +			       RX_COPY_MIN);
>  			dma_sync_single_for_device(&cp->pdev->dev,
>  						   page->dma_addr 
+ off, i,
>  						   
DMA_FROM_DEVICE);
> -			cas_page_unmap(addr);
>  			off += RX_COPY_MIN;
>  			swivel = RX_COPY_MIN;
>  			RX_USED_ADD(page, cp->mtu_stride);
> @@ -2036,10 +2033,8 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, RX_USED_ADD(page, hlen + cp->crc_size);
>  		}
> 
> -		if (cp->crc_size) {
> -			addr = cas_page_map(page->buffer);
> -			crcaddr  = addr + off + hlen;
> -		}
> +		if (cp->crc_size)
> +			crcaddr = page_address(page->buffer) + off + 
hlen;
> 
>  	} else {
>  		/* copying packet */
> @@ -2061,12 +2056,10 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, i += cp->crc_size;
>  		dma_sync_single_for_cpu(&cp->pdev->dev, page->dma_addr + 
off,
>  					i, DMA_FROM_DEVICE);
> -		addr = cas_page_map(page->buffer);
> -		memcpy(p, addr + off, i);
> +		memcpy(p, page_address(page->buffer) + off, i);
>  		dma_sync_single_for_device(&cp->pdev->dev,
>  					   page->dma_addr + off, i,
>  					   DMA_FROM_DEVICE);
> -		cas_page_unmap(addr);
>  		if (p == (char *) skb->data) /* not split */
>  			RX_USED_ADD(page, cp->mtu_stride);
>  		else
> @@ -2081,20 +2074,17 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, page->dma_addr,
>  						dlen + cp-
>crc_size,
>  						DMA_FROM_DEVICE);
> -			addr = cas_page_map(page->buffer);
> -			memcpy(p, addr, dlen + cp->crc_size);
> +			memcpy(p, page_address(page->buffer), dlen + cp-
>crc_size);
>  			dma_sync_single_for_device(&cp->pdev->dev,
>  						   page->dma_addr,
>  						   dlen + cp-
>crc_size,
>  						   
DMA_FROM_DEVICE);
> -			cas_page_unmap(addr);
>  			RX_USED_ADD(page, dlen + cp->crc_size);
>  		}
>  end_copy_pkt:
> -		if (cp->crc_size) {
> -			addr    = NULL;
> +		if (cp->crc_size)
>  			crcaddr = skb->data + alloclen;
> -		}
> +
>  		skb_put(skb, alloclen);
>  	}
> 
> @@ -2103,8 +2093,6 @@ static int cas_rx_process_pkt(struct cas *cp, struct
> cas_rx_comp *rxc, /* checksum includes FCS. strip it out. */
>  		csum = csum_fold(csum_partial(crcaddr, cp->crc_size,
>  					      csum_unfold(csum)));
> -		if (addr)
> -			cas_page_unmap(addr);
>  	}
>  	skb->protocol = eth_type_trans(skb, cp->dev);
>  	if (skb->protocol == htons(ETH_P_IP)) {
> --
> 2.37.2
diff mbox series

Patch

diff --git a/drivers/net/ethernet/sun/cassini.c b/drivers/net/ethernet/sun/cassini.c
index 0aca193..2f66cfc 100644
--- a/drivers/net/ethernet/sun/cassini.c
+++ b/drivers/net/ethernet/sun/cassini.c
@@ -1915,7 +1915,7 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 	int off, swivel = RX_SWIVEL_OFF_VAL;
 	struct cas_page *page;
 	struct sk_buff *skb;
-	void *addr, *crcaddr;
+	void *crcaddr;
 	__sum16 csum;
 	char *p;
 
@@ -1936,7 +1936,7 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 	skb_reserve(skb, swivel);
 
 	p = skb->data;
-	addr = crcaddr = NULL;
+	crcaddr = NULL;
 	if (hlen) { /* always copy header pages */
 		i = CAS_VAL(RX_COMP2_HDR_INDEX, words[1]);
 		page = cp->rx_pages[CAS_VAL(RX_INDEX_RING, i)][CAS_VAL(RX_INDEX_NUM, i)];
@@ -1948,12 +1948,10 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 			i += cp->crc_size;
 		dma_sync_single_for_cpu(&cp->pdev->dev, page->dma_addr + off,
 					i, DMA_FROM_DEVICE);
-		addr = cas_page_map(page->buffer);
-		memcpy(p, addr + off, i);
+		memcpy(p, page_address(page->buffer) + off, i);
 		dma_sync_single_for_device(&cp->pdev->dev,
 					   page->dma_addr + off, i,
 					   DMA_FROM_DEVICE);
-		cas_page_unmap(addr);
 		RX_USED_ADD(page, 0x100);
 		p += hlen;
 		swivel = 0;
@@ -1984,12 +1982,11 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 		/* make sure we always copy a header */
 		swivel = 0;
 		if (p == (char *) skb->data) { /* not split */
-			addr = cas_page_map(page->buffer);
-			memcpy(p, addr + off, RX_COPY_MIN);
+			memcpy(p, page_address(page->buffer) + off,
+			       RX_COPY_MIN);
 			dma_sync_single_for_device(&cp->pdev->dev,
 						   page->dma_addr + off, i,
 						   DMA_FROM_DEVICE);
-			cas_page_unmap(addr);
 			off += RX_COPY_MIN;
 			swivel = RX_COPY_MIN;
 			RX_USED_ADD(page, cp->mtu_stride);
@@ -2036,10 +2033,8 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 			RX_USED_ADD(page, hlen + cp->crc_size);
 		}
 
-		if (cp->crc_size) {
-			addr = cas_page_map(page->buffer);
-			crcaddr  = addr + off + hlen;
-		}
+		if (cp->crc_size)
+			crcaddr = page_address(page->buffer) + off + hlen;
 
 	} else {
 		/* copying packet */
@@ -2061,12 +2056,10 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 			i += cp->crc_size;
 		dma_sync_single_for_cpu(&cp->pdev->dev, page->dma_addr + off,
 					i, DMA_FROM_DEVICE);
-		addr = cas_page_map(page->buffer);
-		memcpy(p, addr + off, i);
+		memcpy(p, page_address(page->buffer) + off, i);
 		dma_sync_single_for_device(&cp->pdev->dev,
 					   page->dma_addr + off, i,
 					   DMA_FROM_DEVICE);
-		cas_page_unmap(addr);
 		if (p == (char *) skb->data) /* not split */
 			RX_USED_ADD(page, cp->mtu_stride);
 		else
@@ -2081,20 +2074,17 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 						page->dma_addr,
 						dlen + cp->crc_size,
 						DMA_FROM_DEVICE);
-			addr = cas_page_map(page->buffer);
-			memcpy(p, addr, dlen + cp->crc_size);
+			memcpy(p, page_address(page->buffer), dlen + cp->crc_size);
 			dma_sync_single_for_device(&cp->pdev->dev,
 						   page->dma_addr,
 						   dlen + cp->crc_size,
 						   DMA_FROM_DEVICE);
-			cas_page_unmap(addr);
 			RX_USED_ADD(page, dlen + cp->crc_size);
 		}
 end_copy_pkt:
-		if (cp->crc_size) {
-			addr    = NULL;
+		if (cp->crc_size)
 			crcaddr = skb->data + alloclen;
-		}
+
 		skb_put(skb, alloclen);
 	}
 
@@ -2103,8 +2093,6 @@  static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc,
 		/* checksum includes FCS. strip it out. */
 		csum = csum_fold(csum_partial(crcaddr, cp->crc_size,
 					      csum_unfold(csum)));
-		if (addr)
-			cas_page_unmap(addr);
 	}
 	skb->protocol = eth_type_trans(skb, cp->dev);
 	if (skb->protocol == htons(ETH_P_IP)) {