PCI: Fix driver_managed_dma check

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Since it's not currently safe to take device_lock() in the IOMMU probe
path, that can race against really_probe() setting dev->driver before
attempting to bind. The race itself isn't so bad, since we're only
concerned with dereferencing dev->driver itself anyway, but sadly my
attempt to implement the check with minimal churn leads to a kind of
Time-of-Check to Time-of-Use (TOCTOU) issue, where dev->driver becomes
valid after to_pci_driver(NULL) is already computed, and thus the check
fails to work as intended.

Will and I both hit this with the platform bus, but the pattern here is
the same, so fix it for correctness too.

Fixes: bcb81ac6ae ("iommu: Get DT/ACPI parsing into the proper probe path")
Reported-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Will McVicker <willmcvicker@google.com>
Link: https://patch.msgid.link/20250425133929.646493-4-robin.murphy@arm.com

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Robin Murphy 2025-04-25 14:39:29 +01:00 • committed by Bjorn Helgaas

parent 19272b37aa

commit 78447d4545

1 changed files with 3 additions and 3 deletions

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drivers/pci/pci-driver.c

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