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Date: Fri, 25 Nov 2022 16:38:30 +0100 From: "Fabio M. De Francesco" <fmdefrancesco@...il.com> To: netdev@...r.kernel.org, Anirudh Venkataramanan <anirudh.venkataramanan@...el.com> Cc: Ira Weiny <ira.weiny@...el.com>, Anirudh Venkataramanan <anirudh.venkataramanan@...el.com> Subject: Re: [PATCH v2 net-next 3/6] cassini: Use page_address() instead of kmap_atomic() 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@...el.com> > Cc: Fabio M. De Francesco <fmdefrancesco@...il.com> > Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@...el.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@...il.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
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