From: Thomas Gleixner <tglx@kernel.org>
To: Joe Damato <joe@dama.to>
Cc: intel-wired-lan@lists.osuosl.org,
Tony Nguyen <anthony.l.nguyen@intel.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
netdev@vger.kernel.org
Subject: Re: i40e: Fix preempt count leak in napi poll tracepoint
Date: Mon, 09 Feb 2026 23:56:29 +0100 [thread overview]
Message-ID: <87a4xhbk6a.ffs@tglx> (raw)
In-Reply-To: <aYpalNvTIiD4nym4@devvm20253.cco0.facebook.com>
On Mon, Feb 09 2026 at 14:07, Joe Damato wrote:
> On Sat, Feb 07, 2026 at 11:50:23AM +0100, Thomas Gleixner wrote:
>> Using get_cpu() in the tracepoint assignment causes an obvious preempt
>> count leak because nothing invokes put_cpu() to undo it:
>>
>> softirq: huh, entered softirq 3 NET_RX with preempt_count 00000100, exited with 00000101?
>>
>> This clearly has seen a lot of testing in the last 3+ years...
>
> I'm the author who introduced the bug. FWIW, I did use it quite a bit when I
> had i40e devices.
Right, but always with PREEMPT_NONE and no debug option which would
enforce PREEMPT_COUNT ...
next prev parent reply other threads:[~2026-02-09 22:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-07 10:50 i40e: Fix preempt count leak in napi poll tracepoint Thomas Gleixner
2026-02-09 22:07 ` Joe Damato
2026-02-09 22:56 ` Thomas Gleixner [this message]
2026-02-10 0:25 ` Thomas Gleixner
2026-02-10 2:58 ` Joe Damato
2026-02-10 7:17 ` [Intel-wired-lan] " Loktionov, Aleksandr
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