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Date: Fri, 18 Nov 2022 09:55:36 -0800 From: Anirudh Venkataramanan <anirudh.venkataramanan@...el.com> To: "Fabio M. De Francesco" <fmdefrancesco@...il.com>, <netdev@...r.kernel.org> CC: Ira Weiny <ira.weiny@...el.com> Subject: Re: [PATCH net-next 3/5] cassini: Remove unnecessary use of kmap_atomic() On 11/18/2022 12:35 AM, Fabio M. De Francesco wrote: > On giovedì 17 novembre 2022 23:25:55 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. >> >> I don't have hardware, so this change has only been compile tested. >> >> Cc: Ira Weiny <ira.weiny@...el.com> >> Cc: Fabio M. De Francesco <fmdefrancesco@...il.com> >> Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@...el.com> >> --- >> drivers/net/ethernet/sun/cassini.c | 34 ++++++++++-------------------- >> 1 file changed, 11 insertions(+), 23 deletions(-) >> >> 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; >> - } >> + > > This is a different logical change. Some maintainers I met would have asked > for a separate patch, but I'm OK with it being here. cas_page_map()/cap_page_unmap() were using addr. Once these went away addr became unnecessary. It would be weird to leave the declaration, init and reinit for a variable that's not of any use, and so it was removed as well. It's cleaner this way. Ani
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