Hi, On Mon, Aug 04, 2014 at 01:42:05PM +0200, Borislav Petkov wrote: > It is always questionable when people remove BUG_ONs because relaxing > assertions sound like a temporary fix more often than not. Sounds to me > that the original commit which deals with BUS_NOTIFY_DEL_DEVICE needs to > try again with the fix. :-)
Actually, as I thought about it again, there is a better fix for this issue that does not require to remove the BUG_ON :) See attached patch: >From 57e2519d5b6e4d8ee840a921300d201ff742c826 Mon Sep 17 00:00:00 2001 From: Joerg Roedel <[email protected]> Date: Tue, 5 Aug 2014 12:55:45 +0200 Subject: [PATCH] iommu/vt-d: Defer domain removal if device is assigned to a driver When the BUS_NOTIFY_DEL_DEVICE event is received the device might still be attached to a driver. In this case the domain can't be released as the mappings might still be in use. Defer the domain removal in this case until we receivce the BUS_NOTIFY_UNBOUND_DRIVER event. Cc: Jiang Liu <[email protected]> Cc: David Woodhouse <[email protected]> Cc: [email protected] # v3.15, v3.16 Signed-off-by: Joerg Roedel <[email protected]> --- drivers/iommu/intel-iommu.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index d1f5caa..5619f26 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -3869,6 +3869,14 @@ static int device_notifier(struct notifier_block *nb, action != BUS_NOTIFY_DEL_DEVICE) return 0; + /* + * If the device is still attached to a device driver we can't + * tear down the domain yet as DMA mappings may still be in use. + * Wait for the BUS_NOTIFY_UNBOUND_DRIVER event to do that. + */ + if (action == BUS_NOTIFY_DEL_DEVICE && dev->driver != NULL) + return 0; + domain = find_domain(dev); if (!domain) return 0; -- 1.8.4.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
