Messages in this thread | | | Date | Fri, 1 Jul 2022 10:33:37 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] PM: runtime: Fix supplier device management during consumer probe |
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On Thu, Jun 30, 2022 at 09:16:41PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Because pm_runtime_get_suppliers() bumps up the rpm_active counter > of each device link to a supplier of the given device in addition > to bumping up the supplier's PM-runtime usage counter, a runtime > suspend of the consumer device may case the latter to go down to 0 > when pm_runtime_put_suppliers() is running on a remote CPU. If that > happens after pm_runtime_put_suppliers() has released power.lock for > the consumer device, and a runtime resume of that device takes place > immediately after it, before pm_runtime_put() is called for the > supplier, that pm_runtime_put() call may cause the supplier to be > suspended even though the consumer is active. > > To prevent that from happening, modify pm_runtime_get_suppliers() to > call pm_runtime_get_sync() for the given device's suppliers without > touching the rpm_active counters of the involved device links > Accordingly, modify pm_runtime_put_suppliers() to call pm_runtime_put() > for the given device's suppliers without looking at the rpm_active > counters of the device links at hand. [This is analogous to what > happened before commit 4c06c4e6cf63 ("driver core: Fix possible > supplier PM-usage counter imbalance").] > > Since pm_runtime_get_suppliers() sets supplier_preactivated for each > device link where the supplier's PM-runtime usage counter has been > incremented and pm_runtime_put_suppliers() calls pm_runtime_put() for > the suppliers whose device links have supplier_preactivated set, the > PM-runtime usage counter is balanced for each supplier and this is > independent of the runtime suspend and resume of the consumer device. > > However, in case a device link with DL_FLAG_PM_RUNTIME set is dropped > during the consumer device probe, so pm_runtime_get_suppliers() bumps > up the supplier's PM-runtime usage counter, but it cannot be dropped by > pm_runtime_put_suppliers(), make device_link_release_fn() take care of > that. > > Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") > Reported-by: Peter Wang <peter.wang@mediatek.com> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > drivers/base/core.c | 10 ++++++++++ > drivers/base/power/runtime.c | 14 +------------- > 2 files changed, 11 insertions(+), 13 deletions(-)
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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