Re: [PATCH] PCI/MSI: msix_setup_msi_descs: Restore logic for msi_attrib.can_mask

[Josef Johansson <josef@xxxxxxxxxxx>]

On 2/11/22 00:55, Bjorn Helgaas wrote:
> [+cc Jason, since you reviewed the original commit]
>
> On Sat, Jan 22, 2022 at 02:10:01AM +0100, Josef Johansson wrote:
>> From: Josef Johansson <josef@xxxxxxxxxxx>
>>
>> PCI/MSI: msix_setup_msi_descs: Restore logic for msi_attrib.can_mask
> Please match the form and style of previous subject lines (in
> particular, omit "msix_setup_msi_descs:").
Would this subject suffice?
PCI/MSI: Correct use of can_mask in msi_add_msi_desc()
>> Commit 71020a3c0dff4 ("PCI/MSI: Use msi_add_msi_desc()") modifies
>> the logic of checking msi_attrib.can_mask, without any reason.
>>     
>> This commits restores that logic.
> I agree, this looks like a typo in 71020a3c0dff4, but I might be
> missing something, so Thomas should take a look, and I added Jason
> since he reviewed it.
>
> Since it was merged by Thomas, I'll let him take care of this, too.
> If it *is* a typo, the fix looks like v5.17 material.
>
> Before: 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/msi/msi.c?id=71020a3c0dff4%5E#n522
> After:  
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/msi/msi.c?id=71020a3c0dff4#n520
It should be noted that I successfully ran the kernel with this patch.
>> Fixes: 71020a3c0dff4 ("PCI/MSI: Use msi_add_msi_desc()")
>> Signed-off-by: Josef Johansson <josef@xxxxxxxxxxx>
>>
>> ---
>> Trying to fix a NULL BUG in the NVMe MSIX implementation I stumbled upon 
>> this code,
>> which ironically was what my last MSI patch resulted into.
>>
>> I don't see any reason why this logic was change, nor do I have the 
>> possibility
>> to see if anything works with my patch or without, since the kernel crashes
>> in other places.
>>
>> As such this is still untested, but as far as I can tell it should restore
>> functionality.
>>
>> Re-sending since it was rejected by linux-pci@xxxxxxxxxxxxxxx due to HTML 
>> contents.
>> Sorry about that.
>>
>> CC xen-devel since it very much relates to Xen kernel (via 
>> pci_msi_ignore_mask).
>> ---
>>
>> diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
>> index c19c7ca58186..146e7b9a01cc 100644
>> --- a/drivers/pci/msi/msi.c
>> +++ b/drivers/pci/msi/msi.c
>> @@ -526,7 +526,7 @@ static int msix_setup_msi_descs(struct pci_dev *dev, 
>> void __iomem *base,
>>              desc.pci.msi_attrib.can_mask = !pci_msi_ignore_mask &&
>>                                             !desc.pci.msi_attrib.is_virtual;
>>  
>> -            if (!desc.pci.msi_attrib.can_mask) {
>> +            if (desc.pci.msi_attrib.can_mask) {
>>                      addr = pci_msix_desc_addr(&desc);
>>                      desc.pci.msix_ctrl = readl(addr + 
>> PCI_MSIX_ENTRY_VECTOR_CTRL);
>>              }
>>
>> --
>> 2.31.1
>>