linux-kernel - [PATCH v2 2/5] hwtracing: hisi_ptt: Handle the interrupt in hardirq context

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Date:   Thu, 14 Sep 2023 19:22:20 +0800
From:   Yicong Yang <yangyicong@...wei.com>
To:     <suzuki.poulose@....com>, <mathieu.poirier@...aro.org>,
        <jonathan.cameron@...wei.com>, <linux-kernel@...r.kernel.org>
CC:     <alexander.shishkin@...ux.intel.com>, <helgaas@...nel.org>,
        <linux-pci@...r.kernel.org>, <prime.zeng@...ilicon.com>,
        <linuxarm@...wei.com>, <yangyicong@...ilicon.com>,
        <hejunhao3@...wei.com>
Subject: [PATCH v2 2/5] hwtracing: hisi_ptt: Handle the interrupt in hardirq context

From: Yicong Yang <yangyicong@...ilicon.com>

Handle the trace interrupt in the hardirq context, make sure the irq
core won't threaded it by declaring IRQF_NO_THREAD and userspace won't
balance it by declaring IRQF_NOBALANCING. Otherwise we may violate the
synchronization requirements of the perf core, referenced to the
change of arm-ccn PMU commit 0811ef7e2f54 ("bus: arm-ccn: fix PMU interrupt flags").

In the interrupt handler we mainly doing 2 things:
- Copy the data from the local DMA buffer to the AUX buffer
- Commit the data in the AUX buffer

Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
---
 drivers/hwtracing/ptt/hisi_ptt.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
index 428cca54217e..3041238a6e54 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.c
+++ b/drivers/hwtracing/ptt/hisi_ptt.c
@@ -346,9 +346,9 @@ static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
 		return ret;
 
 	hisi_ptt->trace_irq = pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ);
-	ret = devm_request_threaded_irq(&pdev->dev, hisi_ptt->trace_irq,
-					NULL, hisi_ptt_isr, 0,
-					DRV_NAME, hisi_ptt);
+	ret = devm_request_irq(&pdev->dev, hisi_ptt->trace_irq, hisi_ptt_isr,
+				IRQF_NOBALANCING | IRQF_NO_THREAD, DRV_NAME,
+				hisi_ptt);
 	if (ret) {
 		pci_err(pdev, "failed to request irq %d, ret = %d\n",
 			hisi_ptt->trace_irq, ret);
-- 
2.24.0