github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-01 19:13:47 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

iommu: Avoid introducing more races

Browse Source 
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>
This commit is contained in:
Robin Murphy 2025-03-11 15:19:25 +00:00 committed by Joerg Roedel
parent 249d3327f0
commit 0c8e9c148e
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/iommu/iommu.c
View File

@ -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