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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev, Thomas Gleixner <tglx@kernel.org>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	Przemek Kitszel <przemyslaw.kitszel@intel.com>,
	intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
	Joe Damato <joe@dama.to>,
	Aleksandr Loktionov <aleksandr.loktionov@intel.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.12 181/265] i40e: Fix preempt count leak in napi poll tracepoint
Date: Thu, 12 Mar 2026 21:09:28 +0100	[thread overview]
Message-ID: <20260312201024.845105273@linuxfoundation.org> (raw)
In-Reply-To: <20260312201018.128816016@linuxfoundation.org>

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

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: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/i40e/i40e_trace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_trace.h b/drivers/net/ethernet/intel/i40e/i40e_trace.h
index 759f3d1c4c8f0..dde0ccd789ed1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_trace.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_trace.h
@@ -88,7 +88,7 @@ TRACE_EVENT(i40e_napi_poll,
 		__entry->rx_clean_complete = rx_clean_complete;
 		__entry->tx_clean_complete = tx_clean_complete;
 		__entry->irq_num = q->irq_num;
-		__entry->curr_cpu = get_cpu();
+		__entry->curr_cpu = smp_processor_id();
 		__assign_str(qname);
 		__assign_str(dev_name);
 		__assign_bitmask(irq_affinity, cpumask_bits(&q->affinity_mask),
-- 
2.51.0




           reply	other threads:[~2026-03-12 20:23 UTC|newest]

Thread overview: expand[flat|nested]  mbox.gz  Atom feed
 [parent not found: <20260312201018.128816016@linuxfoundation.org>]

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