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From:   Yicong Yang <yangyicong@huawei.com>
To:     <suzuki.poulose@arm.com>, <mathieu.poirier@linaro.org>,
        <jonathan.cameron@huawei.com>, <linux-kernel@vger.kernel.org>
CC:     <alexander.shishkin@linux.intel.com>, <helgaas@kernel.org>,
        <linux-pci@vger.kernel.org>, <prime.zeng@hisilicon.com>,
        <linuxarm@huawei.com>, <yangyicong@hisilicon.com>,
        <hejunhao3@huawei.com>
Subject: [PATCH v3 5/5] hwtracing: hisi_ptt: Add dummy callback pmu::read()
Date:   Tue, 10 Oct 2023 16:47:31 +0800
Message-ID: <20231010084731.30450-6-yangyicong@huawei.com>
In-Reply-To: <20231010084731.30450-1-yangyicong@huawei.com>
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From: Junhao He <hejunhao3@huawei.com>

When start trace with perf option "-C $cpu" and immediately stop it
with SIGTERM or others, the perf core will invoke pmu::read() while
the driver doesn't implement it. Add a dummy pmu::read() to avoid
any issues.

Fixes: ff0de066b463 ("hwtracing: hisi_ptt: Add trace function support for HiSilicon PCIe Tune and Trace device")
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/hwtracing/ptt/hisi_ptt.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
index 62a444f5228e..c1b5fd2b8974 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.c
+++ b/drivers/hwtracing/ptt/hisi_ptt.c
@@ -1184,6 +1184,10 @@ static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
 	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
 }
 
+static void hisi_ptt_pmu_read(struct perf_event *event)
+{
+}
+
 static void hisi_ptt_remove_cpuhp_instance(void *hotplug_node)
 {
 	cpuhp_state_remove_instance_nocalls(hisi_ptt_pmu_online, hotplug_node);
@@ -1227,6 +1231,7 @@ static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
 		.stop		= hisi_ptt_pmu_stop,
 		.add		= hisi_ptt_pmu_add,
 		.del		= hisi_ptt_pmu_del,
+		.read		= hisi_ptt_pmu_read,
 	};
 
 	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
-- 
2.24.0