Messages in this thread | | | Date | Fri, 4 Nov 2022 18:36:15 -0700 | From | Brian Norris <> | Subject | Re: [PATCH] iommu: Avoid races around device probe |
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On Fri, Nov 04, 2022 at 07:51:43PM +0000, Robin Murphy wrote: > We currently have 3 different ways that __iommu_probe_device() may be > called, but no real guarantee that multiple callers can't tread on each > other, especially once asynchronous driver probe gets involved. It would > likely have taken a fair bit of luck to hit this previously, but commit > 57365a04c921 ("iommu: Move bus setup to IOMMU device registration") ups > the odds since now it's not just omap-iommu that may trigger multiple > bus_iommu_probe() calls in parallel if probing asynchronously. > > Add a lock to ensure we can't try to double-probe a device, and also > close some possible race windows to make sure we're truly robust against > trying to double-initialise a group via two different member devices. > > Reported-by: Brian Norris <briannorris@chromium.org> > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > drivers/iommu/iommu.c | 28 ++++++++++++++++++++++------ > 1 file changed, 22 insertions(+), 6 deletions(-)
If I've tested appropriately (there's always room for operator error), this seems to resolve the problems I reported:
Tested-by: Brian Norris <briannorris@chromium.org>
I haven't reviewed closely enough to know how precisely this is a regression (your description sounds like you think the bug existed some time before that), but based on testing, this sounds like:
Fixes: 57365a04c921 ("iommu: Move bus setup to IOMMU device registration")
But even if not, the report could probably use:
Link: https://lore.kernel.org/lkml/Y1CHh2oM5wyHs06J@google.com/
And most of all, thanks!
Brian
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