On 10/30/18 11:34 AM, Jens Axboe wrote: > On 10/30/18 11:25 AM, Thomas Gleixner wrote: >> Jens, >> >> On Tue, 30 Oct 2018, Jens Axboe wrote: >>> On 10/30/18 10:02 AM, Keith Busch wrote: >>>> pci_alloc_irq_vectors_affinity() starts at the provided max_vecs. If >>>> that doesn't work, it will iterate down to min_vecs without returning to >>>> the caller. The caller doesn't have a chance to adjust its sets between >>>> iterations when you provide a range. >>>> >>>> The 'masks' overrun problem happens if the caller provides min_vecs >>>> as a smaller value than the sum of the set (plus any reserved). >>>> >>>> If it's up to the caller to ensure that doesn't happen, then min and >>>> max must both be the same value, and that value must also be the same as >>>> the set sum + reserved vectors. The range just becomes redundant since >>>> it is already bounded by the set. >>>> >>>> Using the nvme example, it would need something like this to prevent the >>>> 'masks' overrun: >>> >>> OK, now I hear what you are saying. And you are right, the callers needs >>> to provide minvec == maxvec for sets, and then have a loop around that >>> to adjust as needed. >> >> But then we should enforce it in the core code, right? > > Yes, I was going to ask you if you want a followup patch for that, or > an updated version of the original? Here's an incremental, I'm going to fold this into the original unless I hear otherwise. diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index af24ed50a245..e6c6e10b9ceb 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -1036,6 +1036,13 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec, if (maxvec < minvec) return -ERANGE; + /* + * If the caller is passing in sets, we can't support a range of + * vectors. The caller needs to handle that. + */ + if (affd->nr_sets && minvec != maxvec) + return -EINVAL; + if (WARN_ON_ONCE(dev->msi_enabled)) return -EINVAL; @@ -1087,6 +1094,13 @@ static int __pci_enable_msix_range(struct pci_dev *dev, if (maxvec < minvec) return -ERANGE; + /* + * If the caller is passing in sets, we can't support a range of + * supported vectors. The caller needs to handle that. + */ + if (affd->nr_sets && minvec != maxvec) + return -EINVAL; + if (WARN_ON_ONCE(dev->msix_enabled)) return -EINVAL; -- Jens Axboe
