* [PATCH 6.12 181/265] i40e: Fix preempt count leak in napi poll tracepoint
[not found] <20260312201018.128816016@linuxfoundation.org>
@ 2026-03-12 20:09 ` Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2026-03-12 20:09 UTC (permalink / raw)
To: stable
Cc: Greg Kroah-Hartman, patches, Thomas Gleixner, Tony Nguyen,
Przemek Kitszel, intel-wired-lan, netdev, Joe Damato,
Aleksandr Loktionov, Sasha Levin
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
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