Introduce pcim_alloc_irq_vectors(), a explicit device-managed version of
pci_alloc_irq_vectors().
Suggested-by: Andy Shevchenko <[email protected]>
Signed-off-by: Dejin Zheng <[email protected]>
---
drivers/pci/pci.c | 19 +++++++++++++++++++
include/linux/pci.h | 3 +++
2 files changed, 22 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b67c4327d307..33244b512057 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2054,6 +2054,25 @@ void pcim_pin_device(struct pci_dev *pdev)
}
EXPORT_SYMBOL(pcim_pin_device);
+/**
+ * pcim_alloc_irq_vectors - a device-managed pci_alloc_irq_vectors()
+ *
+ * It depends on calling pcim_enable_device() to make irq resources manageable.
+ */
+int pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
+ unsigned int max_vecs, unsigned int flags)
+{
+ struct pci_devres *dr;
+
+ /*Ensure that the pcim_enable_device() function has been called*/
+ dr = find_pci_dr(dev);
+ if (!dr || !dr->enabled)
+ return -EINVAL;
+
+ return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
+}
+EXPORT_SYMBOL(pcim_alloc_irq_vectors);
+
/*
* pcibios_add_device - provide arch specific hooks when adding device dev
* @dev: the PCI device being added
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 86c799c97b77..d75ba85ddfc5 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1818,6 +1818,9 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
NULL);
}
+int pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
+ unsigned int max_vecs, unsigned int flags);
+
/* Include architecture-dependent settings and functions */
#include <asm/pci.h>
--
2.25.0
Hi Dejin,
Thank you for all the work here!
The subject and the commit message could be improved to include a little
more details about why do you want to do it, and what problems does it
aims to solve.
> Introduce pcim_alloc_irq_vectors(), a explicit device-managed version of
> pci_alloc_irq_vectors().
You can probably drop the "explicit" word from the sentence above.
> +/**
> + * pcim_alloc_irq_vectors - a device-managed pci_alloc_irq_vectors()
> + *
> + * It depends on calling pcim_enable_device() to make irq resources manageable.
> + */
It would be "IRQ" in the sentence above. Also see [1] for more details
about how to make a patch ready to be accepted.
Also, this comment looks like it's intended to be compliant with the
kernel-doc format, and if so, then you should describe each argument as
the bare minimum, so that the entire comment would become this function
documentation making it also a little more useful. See [2] for an
example of how to use kernel-doc.
> +int pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> + unsigned int max_vecs, unsigned int flags)
> +{
> + struct pci_devres *dr;
> +
> + /*Ensure that the pcim_enable_device() function has been called*/
The comment above has to be correctly aligned and it's also missing
spaces around the sentence to be properly formatted, see [3].
> + dr = find_pci_dr(dev);
> + if (!dr || !dr->enabled)
> + return -EINVAL;
> +
> + return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
> +}
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):
>> To automatically use MSI or MSI-X interrupt vectors, use the following
>> function:
>>
>> int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
>> unsigned int max_vecs, unsigned int flags);
>>
>> which allocates up to max_vecs interrupt vectors for a PCI device.
>>
>> (...)
>>
>> Any allocated resources should be freed before removing the device using
>> the following function:
>>
>> void pci_free_irq_vectors(struct pci_dev *dev);
What do you think?
1. https://lore.kernel.org/linux-pci/[email protected]/
2. https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html
3. https://www.kernel.org/doc/html/latest/process/coding-style.html
4. https://www.kernel.org/doc/html/latest/PCI/msi-howto.html
Krzysztof
On Mon, Feb 15, 2021 at 09:55:06PM +0100, Krzysztof Wilczyński wrote:
> 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.
--
With Best Regards,
Andy Shevchenko
On Tue, Feb 16, 2021 at 12:12:39PM +0200, Andy Shevchenko wrote:
> On Mon, Feb 15, 2021 at 09:55:06PM +0100, Krzysztof Wilczyński wrote:
>
> > 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!
BR,
Dejin
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
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