[PATCH v2 06/10] driver core: Avoid endless recursion if device has more than one link
From: Rafael J. Wysocki <hidden>
Date: 2016-09-06 23:03:47
Also in:
linux-iommu, linux-pm, linux-samsung-soc, lkml
On Friday, June 17, 2016 08:26:56 AM Marek Szyprowski wrote:
quoted hunk ↗ jump to hunk
This patch fixes endless recursion, which happends when device has more than one link. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> --- drivers/base/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/drivers/base/core.c b/drivers/base/core.c index 215cd44de761..4e778539b750 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c@@ -57,7 +57,8 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) device_pm_move_last(dev); device_for_each_child(dev, NULL, device_reorder_to_tail); list_for_each_entry(link, &dev->consumer_links, c_node) - device_reorder_to_tail(link->consumer, NULL); + if (link->consumer != dev) + device_reorder_to_tail(link->consumer, NULL); return 0; }
If I'm not mistaken, this should not be necessary unless dev has a link pointing to itself as a consumer. That would be a bug, though. I can add a WARN_ON() to catch this case, but then if there's a link from a consumer of dev pointing back to dev as a consumer, that still will loop forever. I guess we need to detect circular dependencies and fail link creation in such cases. Oh well. Thanks, Rafael