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Re: [PATCH v11 00/60] PCI: Resource allocation cleanup for v4.7

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On Thu, Apr 7, 2016 at 5:15 PM, Yinghai Lu <yinghai@kernel.org> wrote:
>
> After 5b28541552ef (PCI: Restrict 64-bit prefetchable bridge windows
> to 64-bit resources), we have several reports on resource allocation
> failure, and we try to fix the problem with resource clip, and find
> more problems.

Quite frankly, that commit 5b28541552ef is two years old by now, and
went into 3.16.

So whatever problems it caused are kind of water under the bridge.

It worries me a *lot* when there is then a 60-patch series to fix
those alleged problems, because my natural worry ends up being that
the series is as likely to introduce new issues as it is to fix
something that clearly people have been living with for a while now.

I'm not saying that this series is bad, but I *am* saying that at this
point, I'd much rather see this be done as much smaller series, and
merged slowly and carefully. I'm not seeing a lot of people reviewing
the code, but even *with* code review, things like "let's start
allocating from the top of the resource" tends to make me really
really nervous. Because those kinds of patches tend to show problems
even if the code itself was perfectly bug-free, just because it
changes some layout issue and hits some hardware weakness or
undocumented resource allocation issue.

Using tricks like a __weak pcibios_align_end_resource() to only
trigger on one single architecture (despite the naming) makes those
things even subtler.

So please, try to split this up sanely, and let's merge it in sane
pieces. I see that you have that M7101 quirk removal randomly in the
middle of this series, for example, and it doesn't seem to be the only
such random patch. That's entirely independent of all the other
patches in the series (and I thought I acked it already, but
whatever).

Put another way: this is less of a real targeted series, and more of a
random collection of patches. Very few people have the background to
review them, and basically nobody has the ability to test them
(although _individual_ parts of it are obviously testable).

I'd realyl like to see the misc per-device ones separated, for
example. Same for the pure cleanup ones that obviously don't change
any actual semantics. There's a number of those there. And then the
ones that do change real and generic pci allocation code need to be
done in smaller batches so that you don't have "everything changes at
once".

I tried to scan the patches, and I didn't find anything actually
_wrong_. Several looked like "that's an obvious improvement". But
several looked fairly complex, and all _together_ just looked pretty
scary.

              Linus

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[PATCH v11 00/60] PCI: Resource allocation cleanup for v4.7 Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 22/60] PCI: Get new realloc size for bridge for last try Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 42/60] PCI: Skip required+optional if there is no optional Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 25/60] PCI: Reuse res_to_dev_res() in reassign_resources_sorted() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 29/60] PCI: Don't add too much optional size for hotplug bridge MMIO Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 35/60] PCI: Simplify res reference using in __assign_resources_sorted() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 32/60] PCI: Rename pdev_sort_resources() to pdev_assign_resources_prepare() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 34/60] PCI: Add debug printout during releasing partial assigned resources Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 26/60] PCI: Use correct align for optional only resources during sorting Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 38/60] PCI: Check if resource is allocated before trying to assign one Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 31/60] PCI: Remove duplicated code for resource sorting Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 56/60] PCI: Add debug print out for min_align and alt_size Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 12/60] PCI: Check pref compatible bit for mem64 resource of PCIe device Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 58/60] PCI: Introduce resource_disabled() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 24/60] PCI: Cleanup res_to_dev_res() printout Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 39/60] PCI: Separate out save_resources()/restore_resources() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 49/60] PCI: Don't add too much io port for hotplug bridge with old size Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 54/60] resources: Make allocate_resource() return best fit resource Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 46/60] PCI: Fix size calculation with old_size on rescan path Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 48/60] PCI: Move ISA io port align out of calculate_iosize() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 02/60] alpha/PCI: Only check iomem_is_exclusive() for IORESOURCE_MEM, not IORESOURCE_IO Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 41/60] PCI: Separate required+optional assigning to another function Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 33/60] PCI: Treat ROM resource as optional during realloc Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:30 +0200
  [PATCH v11 28/60] PCI: Optimize bus align/size calculation for optional during sizing Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 04/60] sparc/PCI: Use correct offset for bus address to resource Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 23/60] PCI: Don't release sibling bridge resources during hotplug Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 05/60] sparc/PCI: Reserve legacy mmio after PCI mmio Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 53/60] PCI: Kill macro checking for bus io port sizing Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 03/60] PCI: Add pci_find_bus_resource() Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 11/60] OF/PCI: Add IORESOURCE_MEM_64 for 64-bit resource Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 06/60] sparc/PCI: Add IORESOURCE_MEM_64 for 64-bit resource in OF parsing Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 08/60] PCI: Kill wrong quirk about M7101 Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 14/60] PCI: Add has_mem64 for struct host_bridge Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 30/60] PCI: Reorder resources list for required/optional resources Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 44/60] PCI: Add alt_size ressource allocation support Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
    Re: [PATCH v11 44/60] PCI: Add alt_size ressource allocation support Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-08 03:00 +0200
      Re: [PATCH v11 44/60] PCI: Add alt_size ressource allocation support Yinghai Lu <yinghai@kernel.org> - 2016-04-08 08:00 +0200
      Re: [PATCH v11 44/60] PCI: Add alt_size ressource allocation support Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2016-04-08 08:40 +0200
  [PATCH v11 13/60] PCI: Only treat non-pref mmio64 as pref if all bridges have MEM_64 Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  [PATCH v11 19/60] PCI: Set resource to FIXED for LSI devices Yinghai Lu <yinghai@kernel.org> - 2016-04-08 02:40 +0200
  Re: [PATCH v11 00/60] PCI: Resource allocation cleanup for v4.7 Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-08 03:00 +0200
    Re: [PATCH v11 00/60] PCI: Resource allocation cleanup for v4.7 Yinghai Lu <yinghai@kernel.org> - 2016-04-09 07:40 +0200
  [PATCH v11 50/60] PCI: Unify calculate_size() for io port and MMIO Yinghai Lu <yinghai@kernel.org> - 2016-04-08 03:20 +0200

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