linux-kernel - Re: [PATCH v1 1/4] PCI: Introduce pcim_alloc_irq

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Message-ID: <YCvZsy+TXXz6m4iM@rocinante>
Date:   Tue, 16 Feb 2021 15:41:55 +0100
From:   Krzysztof Wilczyński <kw@...ux.com>
To:     Dejin Zheng <zhengdejin5@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        corbet@....net, jarkko.nikula@...ux.intel.com,
        mika.westerberg@...ux.intel.com, rric@...nel.org,
        helgaas@...nel.org, wsa@...nel.org, linux-doc@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/4] PCI: Introduce pcim_alloc_irq_vectors()

Hi Dejin and Andy,

[...]
> > > Question: wouldn't you need to call pci_free_irq_vectors() somewhere,
> > > possibly to pcim_release() callback?  Although, I am not sure where the
> > > right place would be.
> > > 
> > > I am asking, as the documentation (see [4]) suggests that one would have
> > > to release allocated IRQ vectors (relevant exceprt):
> > 
> > It's done in pcim_release() but not explicitly.
> > 
> >         if (dev->msi_enabled)
> >                 pci_disable_msi(dev);
> >         if (dev->msix_enabled)
> >                 pci_disable_msix(dev);
> > 
> > Maybe above can be replaced by pci_free_irq_vectors() to be sure that any
> > future change to PCI IRQ allocation APIs.
> > 
> > Yes, I have checked and currently the above code is equivalent to
> > pci_free_irq_vectors().
> > 
> > Dejin, please update your patch accordingly.
> >
> Hi Andy and Krzysztof,
> 
> I have modified it and sent patch v2. thank you very much!

Thank you Andy for double-checking!  Much appreciated.

Moving to pci_free_irq_vectors() directly looks great as we are also
removing the surplus checks that pcim_release() is doing - since both
the pci_disable_msi() and the pci_disable_msix() are doing internal
validation to see whether MSI/MSI-X is currently enabled.

Thank you again, Dejin and Andy. :)

Krzysztof