dm: Add dm_remove_devices_active() for ordered device removal

This replaces dm_remove_devices_flags() calls in all boot
implementations to ensure non vital devices are consistently removed
first. All boot implementation except arch/arm/lib/bootm.c currently
just call dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL). This can result
in crashes when dependencies between devices exists. The driver model's
design document describes DM_FLAG_VITAL as "indicates that the device is
'vital' to the operation of other devices". Device removal at boot
should follow this.

Instead of adding dm_remove_devices_flags() with (DM_REMOVE_ACTIVE_ALL |
DM_REMOVE_NON_VITAL) everywhere add dm_remove_devices_active() which
does this.

Fixes a NULL pointer deref in the apple dart IOMMU driver during EFI
boot. The xhci-pci (driver which depends on the IOMMU to work) removes
its mapping on removal. This explodes when the IOMMU device was removed
first.

dm_remove_devices_flags() is kept since it is used for testing of
device_remove() calls in dm.

Signed-off-by: Janne Grunau <j@jannau.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 192c120a7d2..974cbfe8400 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -73,11 +73,10 @@ static void announce_and_cleanup(int fake)
 	 * Call remove function of all devices with a removal flag set.
 	 * This may be useful for last-stage operations, like cancelling
 	 * of DMA operation or releasing device internal buffers.
+	 * dm_remove_devices_active() ensures that vital devices are removed in
+	 * a second round.
 	 */
-	dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL | DM_REMOVE_NON_VITAL);
-
-	/* Remove all active vital devices next */
-	dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL);
+	dm_remove_devices_active();
 
 	cleanup_before_linux();
 }