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? -- Jens Axboe
