Re: change MSI/MSI-X APIs

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hi,

On 2015/05/12 23:37, Christos Zoulas wrote:
> In article <55516416.3050901%iij.ad.jp@localhost> you write:
>> Because some device drivers must select INTx, MSI, or MSI-X depending
>> on using devices; e.g. some devices have errata about MSI-X,
>> so the device driver cannot use MSI-X even if the devices have
>> MSI-X capability. In addition, some other the device drivers should
>> use MSI-X and INTx only since some devices have errata about MSI.
>> In a similar way, other device drivers should use MSI-X and MSI only.
>>
>> These selection logic codes can be done only in the device drivers
>> codes, therefore it is required for the device drivers to be able to
>> select interrupt types by allocation APIs.
>>
>>> Also can we add the disestablish/free code in the driver? What are the
>>> steps to undo the interrupt allocation/establishment?
>>
>> Here is the example code of if_wm:
>>    http://www.netbsd.org/~knakahara/unify-msi-apis/if_wm-example.diff
>>
>> This diff includes pci_intr_disestablish()/pci_intr_release() and
>> pci_{intx,msi,msix}_alloc()/pci_intr_establish().
>> How about this sample code?
> 
> I don't see where it free's the sc_intrs[] it allocated in the msi* alloc
> functions. I think that a lot of the code could be merged as follows:
> 
> 	http://www.netbsd.org/~christos/if_wm-example.diff
> 	[I have not even tried to compile this, just some thoughts]
> 
> What do you think?

At first, in my example code of if_wm, "sc->sc_intrs" is allocated by
pci_msix_alloc_exact(), pci_msi_alloc_exact(), or pci_intr_alloc(). 
# pci_msix_alloc_exact() and pci_msi_alloc_exact() allocate the array
# of pci_intr_handle_t (and setting other resources such as mapping
# MSI-X table).
And then "sc->sc_intrs" is freed by pci_intr_release().
# pci_intr_release() free all of the pci_intr_handle_t array (and
# destruct other resources such as unmapping MSI-X table).
I think above.... Well, could you tell me what do you mean
"free's the sc_intrs[]"?

Sorry, my example is a very simple pattern. A practical example is using
multiqueue. In the multiqueue case, the number of TX interrupt handlers
and RX interrupt handlers is decided dynamically by ncpu and the device's
MSI-X vector number. So, in the multiqueue pattern, it cannot use
such *static* struct {} wm_msix_info[].
My example is also intended multiqueue expansion, therefore it divides
processing to establish TX interrupt(s), to establish RX interrupt(s),
and to establish a link-state-changing interrupt.
# "WM_NINTR" must be gone and it is required to decide dynamically
# the number of using interrupts in the future.


Thanks,

-- 
//////////////////////////////////////////////////////////////////////
Internet Initiative Japan Inc.

Device Engineering Section,
Core Product Development Department,
Product Division,
Technology Unit

Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>