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Message-ID: <79eb8baa3f2d96d47ab3e4d4c4c6bdc8bacfa207.camel@gmail.com>
Date: Mon, 06 Feb 2023 08:37:41 -0800
From: Alexander H Duyck <alexander.duyck@...il.com>
To: Geoff Levand <geoff@...radead.org>, netdev@...r.kernel.org,
Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net v4 2/2] net/ps3_gelic_net: Use dma_mapping_error
On Sun, 2023-02-05 at 22:10 +0000, Geoff Levand wrote:
> The current Gelic Etherenet driver was checking the return value of its
> dma_map_single call, and not using the dma_mapping_error() routine.
>
> Fixes runtime problems like these:
>
> DMA-API: ps3_gelic_driver sb_05: device driver failed to check map error
> WARNING: CPU: 0 PID: 0 at kernel/dma/debug.c:1027 .check_unmap+0x888/0x8dc
>
> Fixes: 02c1889166b4 (ps3: gigabit ethernet driver for PS3, take3)
> Signed-off-by: Geoff Levand <geoff@...radead.org>
> ---
> drivers/net/ethernet/toshiba/ps3_gelic_net.c | 52 ++++++++++----------
> 1 file changed, 27 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/net/ethernet/toshiba/ps3_gelic_net.c b/drivers/net/ethernet/toshiba/ps3_gelic_net.c
> index 7a8b5e1e77a6..5622b512e2e4 100644
> --- a/drivers/net/ethernet/toshiba/ps3_gelic_net.c
> +++ b/drivers/net/ethernet/toshiba/ps3_gelic_net.c
> @@ -309,22 +309,34 @@ static int gelic_card_init_chain(struct gelic_card *card,
> struct gelic_descr_chain *chain,
> struct gelic_descr *start_descr, int no)
> {
> - int i;
> + struct device *dev = ctodev(card);
> struct gelic_descr *descr;
> + int i;
>
> - descr = start_descr;
> - memset(descr, 0, sizeof(*descr) * no);
> + memset(start_descr, 0, no * sizeof(*start_descr));
>
> /* set up the hardware pointers in each descriptor */
> - for (i = 0; i < no; i++, descr++) {
> + for (i = 0, descr = start_descr; i < no; i++, descr++) {
> gelic_descr_set_status(descr, GELIC_DESCR_DMA_NOT_IN_USE);
> descr->bus_addr =
> dma_map_single(ctodev(card), descr,
> GELIC_DESCR_SIZE,
> DMA_BIDIRECTIONAL);
Are bus_addr and the CPU the same byte ordering? Just wondering since
this is being passed raw. I would have expected it to go through a
cpu_to_be32.
>
> - if (!descr->bus_addr)
> - goto iommu_error;
> + if (unlikely(dma_mapping_error(dev, descr->bus_addr))) {
The expectation for dma_mapping_error is that the address is in cpu
order. So in this case it is partially correct since bus_addr wasn't
byte swapped, but generally the dma address used should be a CPU byte
ordered variable.
> + dev_err(dev, "%s:%d: dma_mapping_error\n", __func__,
> + __LINE__);
> +
> + for (i--, descr--; i > 0; i--, descr--) {
> + if (descr->bus_addr) {
So I am pretty sure this is broken. Usually for something like this I
will resort to just doing a while (i--) as "i == 0" should be a valid
buffer to have to unmap.
Maybe something like:
while (i--) {
descr--;
Also I think you can get rid of the if since descr->bus_addr should be
valid for all values since you populated it just a few lines above for
each value of i.
> + dma_unmap_single(ctodev(card),
> + descr->bus_addr,
> + GELIC_DESCR_SIZE,
> + DMA_BIDIRECTIONAL);
> + }
> + }
> + return -ENOMEM;
> + }
>
> descr->next = descr + 1;
> descr->prev = descr - 1;
> @@ -334,8 +346,7 @@ static int gelic_card_init_chain(struct gelic_card *card,
> start_descr->prev = (descr - 1);
>
> /* chain bus addr of hw descriptor */
> - descr = start_descr;
> - for (i = 0; i < no; i++, descr++) {
> + for (i = 0, descr = start_descr; i < no; i++, descr++) {
> descr->next_descr_addr = cpu_to_be32(descr->next->bus_addr);
> }
>
This seems like an unrelated change that was snuck in.
> @@ -346,14 +357,6 @@ static int gelic_card_init_chain(struct gelic_card *card,
> (descr - 1)->next_descr_addr = 0;
>
> return 0;
> -
> -iommu_error:
> - for (i--, descr--; 0 <= i; i--, descr--)
> - if (descr->bus_addr)
> - dma_unmap_single(ctodev(card), descr->bus_addr,
> - GELIC_DESCR_SIZE,
> - DMA_BIDIRECTIONAL);
> - return -ENOMEM;
> }
>
> /**
> @@ -407,19 +410,18 @@ static int gelic_descr_prepare_rx(struct gelic_card *card,
> cpu_addr = dma_map_single(dev, descr->skb->data, descr->buf_size,
> DMA_FROM_DEVICE);
>
> - descr->buf_addr = cpu_to_be32(cpu_addr);
> -
> - if (!descr->buf_addr) {
> + if (unlikely(dma_mapping_error(dev, cpu_addr))) {
> + dev_err(dev, "%s:%d: dma_mapping_error\n", __func__, __LINE__);
> dev_kfree_skb_any(descr->skb);
> descr->buf_addr = 0;
> descr->buf_size = 0;
> descr->skb = NULL;
> - dev_info(dev,
> - "%s:Could not iommu-map rx buffer\n", __func__);
> gelic_descr_set_status(descr, GELIC_DESCR_DMA_NOT_IN_USE);
> return -ENOMEM;
> }
>
> + descr->buf_addr = cpu_to_be32(cpu_addr);
> +
Okay, so this addresses the comment I had in the earlier patch.
> gelic_descr_set_status(descr, GELIC_DESCR_DMA_CARDOWNED);
> return 0;
> }
> @@ -775,6 +777,7 @@ static int gelic_descr_prepare_tx(struct gelic_card *card,
> struct gelic_descr *descr,
> struct sk_buff *skb)
> {
> + struct device *dev = ctodev(card);
> dma_addr_t buf;
>
> if (card->vlan_required) {
> @@ -789,11 +792,10 @@ static int gelic_descr_prepare_tx(struct gelic_card *card,
> skb = skb_tmp;
> }
>
> - buf = dma_map_single(ctodev(card), skb->data, skb->len, DMA_TO_DEVICE);
> + buf = dma_map_single(dev, skb->data, skb->len, DMA_TO_DEVICE);
>
> - if (!buf) {
> - dev_err(ctodev(card),
> - "dma map 2 failed (%p, %i). Dropping packet\n",
> + if (unlikely(dma_mapping_error(dev, buf))) {
> + dev_err(dev, "dma map 2 failed (%p, %i). Dropping packet\n",
> skb->data, skb->len);
> return -ENOMEM;
> }
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