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| author |   Robin Murphy <robin.murphy@arm.com> | 2025-03-11 15:19:25 +0000 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-04 14:46:27 +0200 |
| commit | 9eff7605ebccdba7b3d83bbe9043bb9c14fedb13 (patch) | |
| tree | b3a71df0d657f5f7809ec1f6fbdcbb6314e1c6da | |
| parent | coredump: hand a pidfd to the usermode coredump helper (diff) | |
| download | laptop-kernel-9eff7605ebccdba7b3d83bbe9043bb9c14fedb13.tar.xz laptop-kernel-9eff7605ebccdba7b3d83bbe9043bb9c14fedb13.zip | |
iommu: Avoid introducing more races
commit 0c8e9c148e29a983e67060fb4944a8ca79d4362a upstream.
Although the lock-juggling is only a temporary workaround, we don't want
it to make things avoidably worse. Jason was right to be nervous, since
bus_iommu_probe() doesn't care *which* IOMMU instance it's probing for,
so it probably is possible for one walk to finish a probe which a
different walk started, thus we do want to check for that.
Also there's no need to drop the lock just to have of_iommu_configure()
do nothing when a fwspec already exists; check that directly and avoid
opening a window at all in that (still somewhat likely) case.
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/09d901ad11b3a410fbb6e27f7d04ad4609c3fe4a.1741706365.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/iommu/iommu.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 9d728800a862..ee9c62150b56 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -422,13 +422,15 @@ static int iommu_init_device(struct device *dev) * is buried in the bus dma_configure path. Properly unpicking that is * still a big job, so for now just invoke the whole thing. The device * already having a driver bound means dma_configure has already run and - * either found no IOMMU to wait for, or we're in its replay call right - * now, so either way there's no point calling it again. + * found no IOMMU to wait for, so there's no point calling it again. */ - if (!dev->driver && dev->bus->dma_configure) { + if (!dev->iommu->fwspec && !dev->driver && dev->bus->dma_configure) { mutex_unlock(&iommu_probe_device_lock); dev->bus->dma_configure(dev); mutex_lock(&iommu_probe_device_lock); + /* If another instance finished the job for us, skip it */ + if (!dev->iommu || dev->iommu_group) + return -ENODEV; } /* * At this point, relevant devices either now have a fwspec which will |