From: Jacob Keller <jacob.e.keller@intel.com>
To: <charles_xu@189.cn>, <tglx@kernel.org>,
<anthony.l.nguyen@intel.com>, <przemyslaw.kitszel@intel.com>,
<intel-wired-lan@lists.osuosl.org>, <netdev@vger.kernel.org>,
<joe@dama.to>, <aleksandr.loktionov@intel.com>,
<stable@vger.kernel.org>
Subject: Re: [PATCH 6.6.y] i40e: Fix preempt count leak in napi poll tracepoint
Date: Thu, 23 Apr 2026 10:38:58 -0700 [thread overview]
Message-ID: <e256413a-531e-462e-8d8b-ab42f3fc4d18@intel.com> (raw)
In-Reply-To: <20260421071838.3878-1-charles_xu@189.cn>
On 4/21/2026 12:18 AM, charles_xu@189.cn wrote:
> From: Thomas Gleixner <tglx@kernel.org>
>
> [ Upstream commit 4b3d54a85bd37ebf2d9836f0d0de775c0ff21af9 ]
>
> 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...
>
> Use smp_processor_id() instead.
>
> Fixes: 6d4d584a7ea8 ("i40e: Add i40e_napi_poll tracepoint")
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
> Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
> Cc: intel-wired-lan@lists.osuosl.org
> Cc: netdev@vger.kernel.org
> Reviewed-by: Joe Damato <joe@dama.to>
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
> Signed-off-by: Charles Xu <charles_xu@189.cn>
> ---
This was already backported 6.12, but wasn't in v6.6. The v6.6 tree does
have the i40e_napi_poll tracepoint, so it makes sense to backport this
there as well.
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
prev parent reply other threads:[~2026-04-23 17:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-21 7:18 [PATCH 6.6.y] i40e: Fix preempt count leak in napi poll tracepoint charles_xu
2026-04-23 17:38 ` Jacob Keller [this message]
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