4.17-stable review patch. If anyone has any objections, please let me know.
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From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit 47e5abfb546a3ace23a77453dc2e9db92704c5ac upstream.
If a device link is added via device_link_add() by the driver of the link's consumer device, the supplier's runtime PM usage counter is going to be dropped by the pm_runtime_put_suppliers() call in driver_probe_device(). However, in that case it is not incremented unless the supplier driver is already present and the link is not stateless. That leads to a runtime PM usage counter imbalance for the supplier device in a few cases.
To prevent that from happening, bump up the supplier runtime PM usage counter in device_link_add() for all links with the DL_FLAG_PM_RUNTIME flag set that are added at the consumer probe time. Use pm_runtime_get_noresume() for that as the callers of device_link_add() who want the supplier to be resumed by it are expected to pass DL_FLAG_RPM_ACTIVE in flags to it anyway, but additionally resume the supplier if the link is added during consumer driver probe to retain the existing behavior for the callers depending on it.
Fixes: 21d5c57b3726 (PM / runtime: Use device links) Reported-by: Ulf Hansson ulf.hansson@linaro.org Reviewed-by: Ulf Hansson ulf.hansson@linaro.org Tested-by: Marek Szyprowski m.szyprowski@samsung.com Cc: 4.10+ stable@vger.kernel.org # 4.10+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/base/core.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
--- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -216,6 +216,13 @@ struct device_link *device_link_add(stru link->rpm_active = true; } pm_runtime_new_link(consumer); + /* + * If the link is being added by the consumer driver at probe + * time, balance the decrementation of the supplier's runtime PM + * usage counter after consumer probe in driver_probe_device(). + */ + if (consumer->links.status == DL_DEV_PROBING) + pm_runtime_get_noresume(supplier); } get_device(supplier); link->supplier = supplier; @@ -235,12 +242,12 @@ struct device_link *device_link_add(stru switch (consumer->links.status) { case DL_DEV_PROBING: /* - * Balance the decrementation of the supplier's - * runtime PM usage counter after consumer probe - * in driver_probe_device(). + * Some callers expect the link creation during + * consumer driver probe to resume the supplier + * even without DL_FLAG_RPM_ACTIVE. */ if (flags & DL_FLAG_PM_RUNTIME) - pm_runtime_get_sync(supplier); + pm_runtime_resume(supplier);
link->status = DL_STATE_CONSUMER_PROBE; break;