linux-kernel - Re: revert bab65e48cb064 PCI/MSI Sanitize MSI-X checks

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Date:   Fri, 7 Apr 2023 12:26:26 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     David Laight <David.Laight@...lab.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Gunthorpe <jgg@...dia.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: revert bab65e48cb064 PCI/MSI Sanitize MSI-X checks

On Fri, Apr 7, 2023 at 5:25 AM David Laight <David.Laight@...lab.com> wrote:
>
> I think it depends on why the driver is asking for more
> interrupts than the hardware supports.
> Potentially the driver could do:
>         for (i = 0; i < 8; i++)
>                 msix_tbl[i].entry = 2 * i;
> if the hardware supports 8 interrupts perhaps it
> should return 4?

Hmm.

Something like this might get that case right too. Again - entirely
untested, but looks superficially sane to me.

It just returns how many of the msix_entry[] entries can be used (or
negative for error). So then the (only) caller can just say "is that
still enough for what we required". Seems reasonable, and would get
that non-contiguous case right, I think.

Thomas?

I'm going to drop this and assume I'll get a pull from you with what
you consider the proper fix, but since I was looking at this anyway, I
decided I might as well send out this RFC patch.

                Linus

View attachment "patch.diff" of type "text/x-patch" (1911 bytes)