From: Heiner Kallweit <hkallweit1@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: David Miller <davem@davemloft.net>,
Realtek linux nic maintainers <nic_swsd@realtek.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Maxim Plotnikov <wgh@torlan.ru>
Subject: Re: [PATCH net] r8169: work around short packet hw bug on RTL8125
Date: Thu, 5 Nov 2020 11:31:48 +0100 [thread overview]
Message-ID: <4bd669af-847f-020e-9c80-51ff325b4cbc@gmail.com> (raw)
In-Reply-To: <20201104174521.2a902678@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On 05.11.2020 02:45, Jakub Kicinski wrote:
> On Tue, 3 Nov 2020 18:52:18 +0100 Heiner Kallweit wrote:
>> Network problems with RTL8125B have been reported [0] and with help
>> from Realtek it turned out that this chip version has a hw problem
>> with short packets (similar to RTL8168evl). Having said that activate
>> the same workaround as for RTL8168evl.
>> Realtek suggested to activate the workaround for RTL8125A too, even
>> though they're not 100% sure yet which RTL8125 versions are affected.
>>
>> [0] https://bugzilla.kernel.org/show_bug.cgi?id=209839
>>
>> Fixes: 0439297be951 ("r8169: add support for RTL8125B")
>> Reported-by: Maxim Plotnikov <wgh@torlan.ru>
>> Tested-by: Maxim Plotnikov <wgh@torlan.ru>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>
> Applied, thanks!
>
>> @@ -4125,7 +4133,7 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private *tp,
>>
>> opts[1] |= transport_offset << TCPHO_SHIFT;
>> } else {
>> - if (unlikely(rtl_test_hw_pad_bug(tp, skb)))
>> + if (unlikely(skb->len < ETH_ZLEN && rtl_test_hw_pad_bug(tp)))
>> return !eth_skb_pad(skb);
>> }
>
> But looks like we may have another bug here - looks like this function
> treas skb_cow_head() and eth_skb_pad() failures the same, but former
> doesn't free the skb on error, while the latter does.
>
Thanks for the hint, indeed we have an issue. The caller of
rtl8169_tso_csum_v2() also frees the skb if false is returned, therefore
we have a double free if eth_skb_pad() fails.
When checking eth_skb_pad() I saw that it uses kfree_skb() to free
the skb on error. Kernel documentation say about ndo_start_xmit context:
Process with BHs disabled or BH (timer),
will be called with interrupts disabled by netconsole.
Is it safe to use kfree_skb() if interrupts are disabled?
I'm asking because dev_kfree_skb_any() uses the irq path if
irqs_disabled() is true.
next prev parent reply other threads:[~2020-11-05 10:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 17:52 [PATCH net] r8169: work around short packet hw bug on RTL8125 Heiner Kallweit
2020-11-05 1:45 ` Jakub Kicinski
2020-11-05 10:31 ` Heiner Kallweit [this message]
2020-11-05 16:13 ` Jakub Kicinski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4bd669af-847f-020e-9c80-51ff325b4cbc@gmail.com \
--to=hkallweit1@gmail.com \
--cc=davem@davemloft.net \
--cc=kuba@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=nic_swsd@realtek.com \
--cc=wgh@torlan.ru \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).