From: David Laight <david.laight.linux@gmail•com>
To: Alexander Lobakin <aleksander.lobakin@intel•com>
Cc: Justin Lai <justinlai0215@realtek•com>, <kuba@kernel•org>,
<davem@davemloft•net>, <edumazet@google•com>, <pabeni@redhat•com>,
<andrew+netdev@lunn•ch>, <linux-kernel@vger•kernel.org>,
<netdev@vger•kernel.org>, <horms@kernel•org>,
<pkshih@realtek•com>, <larry.chiu@realtek•com>
Subject: Re: [PATCH] rtase: Avoid sleeping in get_stats64()
Date: Mon, 1 Jun 2026 22:42:03 +0100 [thread overview]
Message-ID: <20260601224203.5d282c21@pumpkin> (raw)
In-Reply-To: <f4b96c08-c6f7-422f-aceb-aa48fa2bfef6@intel.com>
On Mon, 1 Jun 2026 15:14:50 +0200
Alexander Lobakin <aleksander.lobakin@intel•com> wrote:
> From: Justin Lai <justinlai0215@realtek•com>
> Date: Mon, 1 Jun 2026 14:24:47 +0800
>
> > The .ndo_get_stats64 callback must not sleep because it can be
> > called when reading /proc/net/dev.
> >
> > rtase_get_stats64() calls rtase_dump_tally_counter(), which polls
> > the tally counter dump bit with read_poll_timeout(). This may
> > sleep while waiting for the hardware counter dump to complete.
> >
> > Use read_poll_timeout_atomic() instead to avoid sleeping in the
> > get_stats64() path.
> >
> > Signed-off-by: Justin Lai <justinlai0215@realtek•com>
>
> Looks legit.
>
> One question: for how long can this poll for in real life scenarios? Up
> to ~1 ms is okay-ish for atomic, but if longer, then you'd better to
> split it into shorter polls and reschedule() time to time.
Anyone trying to get a thread running at an RT priority won't thank you
for spinning for anywhere near that long.
When an RT processes becomes runnable the scheduler will preempt a lower
priority process that is running on the cpu the RT process last ran on.
The RT process won't run until the preempt actually happens.
1ms is a very long time.
-- David
>
> Thanks,
> Olek
>
next prev parent reply other threads:[~2026-06-01 21:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-01 6:24 [PATCH] rtase: Avoid sleeping in get_stats64() Justin Lai
2026-06-01 13:14 ` Alexander Lobakin
2026-06-01 21:42 ` David Laight [this message]
2026-06-02 13:43 ` Alexander Lobakin
2026-06-03 9:59 ` David Laight
2026-06-03 13:26 ` Alexander Lobakin
2026-06-02 10:50 ` Justin Lai
2026-06-02 18:09 ` Jakub Kicinski
2026-06-03 4:08 ` Justin Lai
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