From: Benjamin Herrenschmidt <benh@kernel.crashing.org> To: Dylan Hung <dylan_hung@aspeedtech.com>, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ratbert@faraday-tech.com, linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org Cc: BMC-SW@aspeedtech.com, Joel Stanley <joel@jms.id.au> Subject: Re: [PATCH 1/4] ftgmac100: Fix race issue on TX descriptor[0] Date: Tue, 20 Oct 2020 10:19:25 +1100 [thread overview] Message-ID: <be7a978c48c9f1c6c29583350dee6168385c3039.camel@kernel.crashing.org> (raw) In-Reply-To: <20201019085717.32413-2-dylan_hung@aspeedtech.com> On Mon, 2020-10-19 at 16:57 +0800, Dylan Hung wrote: > These rules must be followed when accessing the TX descriptor: > > 1. A TX descriptor is "cleanable" only when its value is non-zero > and the owner bit is set to "software" Can you elaborate ? What is the point of that change ? The owner bit should be sufficient, why do we need to check other fields ? > 2. A TX descriptor is "writable" only when its value is zero > regardless the edotr mask. Again, why is that ? Can you elaborate ? What race are you trying to address here ? Cheers, Ben. > Fixes: 52c0cae87465 ("ftgmac100: Remove tx descriptor accessors") > Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com> > Signed-off-by: Joel Stanley <joel@jms.id.au> > --- > drivers/net/ethernet/faraday/ftgmac100.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c > b/drivers/net/ethernet/faraday/ftgmac100.c > index 00024dd41147..7cacbe4aecb7 100644 > --- a/drivers/net/ethernet/faraday/ftgmac100.c > +++ b/drivers/net/ethernet/faraday/ftgmac100.c > @@ -647,6 +647,9 @@ static bool ftgmac100_tx_complete_packet(struct > ftgmac100 *priv) > if (ctl_stat & FTGMAC100_TXDES0_TXDMA_OWN) > return false; > > + if ((ctl_stat & ~(priv->txdes0_edotr_mask)) == 0) > + return false; > + > skb = priv->tx_skbs[pointer]; > netdev->stats.tx_packets++; > netdev->stats.tx_bytes += skb->len; > @@ -756,6 +759,9 @@ static netdev_tx_t > ftgmac100_hard_start_xmit(struct sk_buff *skb, > pointer = priv->tx_pointer; > txdes = first = &priv->txdes[pointer]; > > + if (le32_to_cpu(txdes->txdes0) & ~priv->txdes0_edotr_mask) > + goto drop; > + > /* Setup it up with the packet head. Don't write the head to > the > * ring just yet > */ > @@ -787,6 +793,10 @@ static netdev_tx_t > ftgmac100_hard_start_xmit(struct sk_buff *skb, > /* Setup descriptor */ > priv->tx_skbs[pointer] = skb; > txdes = &priv->txdes[pointer]; > + > + if (le32_to_cpu(txdes->txdes0) & ~priv- > >txdes0_edotr_mask) > + goto dma_err; > + > ctl_stat = ftgmac100_base_tx_ctlstat(priv, pointer); > ctl_stat |= FTGMAC100_TXDES0_TXDMA_OWN; > ctl_stat |= FTGMAC100_TXDES0_TXBUF_SIZE(len);
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org> To: Dylan Hung <dylan_hung@aspeedtech.com>, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ratbert@faraday-tech.com, linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org Cc: BMC-SW@aspeedtech.com Subject: Re: [PATCH 1/4] ftgmac100: Fix race issue on TX descriptor[0] Date: Tue, 20 Oct 2020 10:19:25 +1100 [thread overview] Message-ID: <be7a978c48c9f1c6c29583350dee6168385c3039.camel@kernel.crashing.org> (raw) In-Reply-To: <20201019085717.32413-2-dylan_hung@aspeedtech.com> On Mon, 2020-10-19 at 16:57 +0800, Dylan Hung wrote: > These rules must be followed when accessing the TX descriptor: > > 1. A TX descriptor is "cleanable" only when its value is non-zero > and the owner bit is set to "software" Can you elaborate ? What is the point of that change ? The owner bit should be sufficient, why do we need to check other fields ? > 2. A TX descriptor is "writable" only when its value is zero > regardless the edotr mask. Again, why is that ? Can you elaborate ? What race are you trying to address here ? Cheers, Ben. > Fixes: 52c0cae87465 ("ftgmac100: Remove tx descriptor accessors") > Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com> > Signed-off-by: Joel Stanley <joel@jms.id.au> > --- > drivers/net/ethernet/faraday/ftgmac100.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c > b/drivers/net/ethernet/faraday/ftgmac100.c > index 00024dd41147..7cacbe4aecb7 100644 > --- a/drivers/net/ethernet/faraday/ftgmac100.c > +++ b/drivers/net/ethernet/faraday/ftgmac100.c > @@ -647,6 +647,9 @@ static bool ftgmac100_tx_complete_packet(struct > ftgmac100 *priv) > if (ctl_stat & FTGMAC100_TXDES0_TXDMA_OWN) > return false; > > + if ((ctl_stat & ~(priv->txdes0_edotr_mask)) == 0) > + return false; > + > skb = priv->tx_skbs[pointer]; > netdev->stats.tx_packets++; > netdev->stats.tx_bytes += skb->len; > @@ -756,6 +759,9 @@ static netdev_tx_t > ftgmac100_hard_start_xmit(struct sk_buff *skb, > pointer = priv->tx_pointer; > txdes = first = &priv->txdes[pointer]; > > + if (le32_to_cpu(txdes->txdes0) & ~priv->txdes0_edotr_mask) > + goto drop; > + > /* Setup it up with the packet head. Don't write the head to > the > * ring just yet > */ > @@ -787,6 +793,10 @@ static netdev_tx_t > ftgmac100_hard_start_xmit(struct sk_buff *skb, > /* Setup descriptor */ > priv->tx_skbs[pointer] = skb; > txdes = &priv->txdes[pointer]; > + > + if (le32_to_cpu(txdes->txdes0) & ~priv- > >txdes0_edotr_mask) > + goto dma_err; > + > ctl_stat = ftgmac100_base_tx_ctlstat(priv, pointer); > ctl_stat |= FTGMAC100_TXDES0_TXDMA_OWN; > ctl_stat |= FTGMAC100_TXDES0_TXBUF_SIZE(len);
next prev parent reply other threads:[~2020-10-19 23:30 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-19 8:57 [PATCH 0/4] fix ftgmac100 issues on aspeed soc Dylan Hung 2020-10-19 8:57 ` Dylan Hung 2020-10-19 8:57 ` [PATCH 1/4] ftgmac100: Fix race issue on TX descriptor[0] Dylan Hung 2020-10-19 8:57 ` Dylan Hung 2020-10-19 23:19 ` Benjamin Herrenschmidt [this message] 2020-10-19 23:19 ` Benjamin Herrenschmidt 2020-10-20 4:13 ` Joel Stanley 2020-10-20 4:13 ` Joel Stanley 2020-10-20 6:23 ` Benjamin Herrenschmidt 2020-10-20 6:23 ` Benjamin Herrenschmidt 2020-10-20 7:13 ` Joel Stanley 2020-10-20 7:13 ` Joel Stanley 2020-10-19 8:57 ` [PATCH 2/4] ftgmac100: Fix missing-poll issue Dylan Hung 2020-10-19 8:57 ` Dylan Hung 2020-10-19 8:57 ` [PATCH 3/4] ftgmac100: Add a dummy read to ensure running sequence Dylan Hung 2020-10-19 8:57 ` Dylan Hung 2020-10-19 23:25 ` Benjamin Herrenschmidt 2020-10-19 23:25 ` Benjamin Herrenschmidt 2020-10-19 8:57 ` [PATCH 4/4] ftgmac100: Restart MAC HW once Dylan Hung 2020-10-19 8:57 ` Dylan Hung 2020-10-19 23:26 ` Benjamin Herrenschmidt 2020-10-19 23:26 ` Benjamin Herrenschmidt 2020-10-20 4:14 ` Joel Stanley 2020-10-20 4:14 ` Joel Stanley 2021-03-12 0:26 ` Joel Stanley 2021-03-12 0:26 ` Joel Stanley 2021-03-12 0:28 ` David Miller 2021-03-12 0:28 ` David Miller
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