[PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface

Alexander Gordeev agordeev at redhat.com
Thu Sep 26 23:03:29 EST 2013

On Thu, Sep 26, 2013 at 08:32:53AM -0400, Mark Lord wrote:
> On 13-09-18 05:48 AM, Alexander Gordeev wrote:
> > The last pattern makes most of sense to me and could be updated with a more
> > clear sequence - a call to (bit modified) pci_msix_table_size() followed
> > by a call to pci_enable_msix(). I think this pattern can effectively
> > supersede the currently recommended "loop" practice.
> The loop is still necessary, because there's a race between those two calls,
> so that pci_enable_msix() can still fail due to lack of MSIX slots.

Moreover, the existing loop pattern is racy and could fail just as easily ;)
But (1) that is something drivers should expect and (2) there is basically
nothing to race against - that is probably the reason it has not been a
problem for pSeries. So I think we should not care about this.

Alexander Gordeev
agordeev at redhat.com

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