Re: [PATCH v4 5/5] hwtracing: hisi_ptt: Fix potential sleep in atomic context

[Jonathan Cameron]

On Tue, 6 Jun 2023 22:22:44 +0800
Yicong Yang <yangyicong@xxxxxxxxxx> wrote:

> From: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxx>

LGTM

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>