From: Sergey Shtylyov <s.shtylyov@omp.ru>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>,
<netdev@vger.kernel.org>, <linux-renesas-soc@vger.kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] sh_eth: remove open coded netif_running()
Date: Sat, 25 Mar 2023 23:56:09 +0300 [thread overview]
Message-ID: <346b2451-6862-011e-9842-284a43fcf337@omp.ru> (raw)
In-Reply-To: <CAMuHMdUt_kTH3tnrdF=oKBLyjrstei8PLsyr+dFXVoPEyxTLAA@mail.gmail.com>
Hello!
On 3/23/23 11:32 AM, Geert Uytterhoeven wrote:
[...]
>>> It had a purpose back in the days, but today we have a handy helper.
>>
>> Well, the is_opened flag doesn't get set/cleared at the same time as
>> __LINK_STATE_START. I'm not sure they are interchangeable...
>>
>>> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
>>> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>
>>> --- a/drivers/net/ethernet/renesas/sh_eth.c
>>> +++ b/drivers/net/ethernet/renesas/sh_eth.c
>>> @@ -2441,8 +2441,6 @@ static int sh_eth_open(struct net_device *ndev)
>>>
>>> netif_start_queue(ndev);
>>>
>>> - mdp->is_opened = 1;
>>> -
>>
>> __LINK_STATE_START gets set before the ndo_open() method call, so
>> before the RPM call that enbales the clocks...
>>
>>> return ret;
>>>
>>> out_free_irq:
>>> @@ -2565,7 +2563,7 @@ static struct net_device_stats *sh_eth_get_stats(struct net_device *ndev)
>>> if (mdp->cd->no_tx_cntrs)
>>> return &ndev->stats;
>>>
>>> - if (!mdp->is_opened)
>>> + if (!netif_running(ndev))
>>> return &ndev->stats;
>>
>> I guess mdp->is_opened is checked here to avoid reading the counter
>> regs when RPM hasn't been called yet to enable the clocks...
>
> Exactly, cfr. commit 7fa2955ff70ce453 ("sh_eth: Fix sleeping function
> called from invalid context").
Yeah, pm_runtime_get_sync() couldn't be called in this case as
netstat_show() invoked read_lock() that ensued calling preempt_disable()...
> So you mean sh_eth_get_stats() can now be called after setting
> __LINK_STATE_START, but before RPM has enabled the clocks?
Yes, probably...
> Is there some protection against parallel execution of ndo_open()
> and get_stats()?
Haven't seen it (yet?)...
> Gr{oetje,eeting}s,
>
> Geert
MBR, Sergey
prev parent reply other threads:[~2023-03-25 20:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-21 6:58 [PATCH net-next] sh_eth: remove open coded netif_running() Wolfram Sang
2023-03-21 8:22 ` Leon Romanovsky
2023-03-21 14:33 ` Geert Uytterhoeven
2023-03-21 16:58 ` Florian Fainelli
2023-03-22 12:30 ` patchwork-bot+netdevbpf
2023-03-22 20:57 ` Sergey Shtylyov
2023-03-22 20:54 ` Sergey Shtylyov
2023-03-23 8:32 ` Geert Uytterhoeven
2023-03-23 16:40 ` Jakub Kicinski
2023-03-25 20:27 ` Sergey Shtylyov
2023-03-27 8:14 ` Wolfram Sang
2023-03-25 20:56 ` Sergey Shtylyov [this message]
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=346b2451-6862-011e-9842-284a43fcf337@omp.ru \
--to=s.shtylyov@omp.ru \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=geert+renesas@glider.be \
--cc=geert@linux-m68k.org \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-renesas-soc@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=wsa+renesas@sang-engineering.com \
/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).