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Date:   Tue, 6 Jun 2023 17:43:05 +0100
From:   Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To:     Yicong Yang <yangyicong@huawei.com>
CC:     <mathieu.poirier@linaro.org>, <suzuki.poulose@arm.com>,
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        <yangyicong@hisilicon.com>
Subject: Re: [PATCH v4 5/5] hwtracing: hisi_ptt: Fix potential sleep in
 atomic context
Message-ID: <20230606174305.00005a10@Huawei.com>
In-Reply-To: <20230606142244.10939-6-yangyicong@huawei.com>
References: <20230606142244.10939-1-yangyicong@huawei.com>
        <20230606142244.10939-6-yangyicong@huawei.com>
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On Tue, 6 Jun 2023 22:22:44 +0800
Yicong Yang <yangyicong@huawei.com> wrote:

> From: Yicong Yang <yangyicong@hisilicon.com>
> 
> We're using pci_irq_vector() to obtain the interrupt number and then
> bind it to the CPU start perf under the protection of spinlock in
> pmu::start(). pci_irq_vector() might sleep since [1] because it will
> call msi_domain_get_virq() to get the MSI interrupt number and it
> needs to acquire dev->msi.data->mutex. Getting a mutex will sleep on
> contention. So use pci_irq_vector() in an atomic context is problematic.
> 
> This patch cached the interrupt number in the probe() and uses the
> cached data instead to avoid potential sleep.
> 
> [1] commit 82ff8e6b78fc ("PCI/MSI: Use msi_get_virq() in pci_get_vector()")
> Fixes: ff0de066b463 ("hwtracing: hisi_ptt: Add trace function support for HiSilicon PCIe Tune and Trace device")
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>

LGTM

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>