linux_dsm_epyc7002/include
Rafael J. Wysocki 4c06c4e6cf driver core: Fix possible supplier PM-usage counter imbalance
If a stateless device link to a certain supplier with
DL_FLAG_PM_RUNTIME set in the flags is added and then removed by the
consumer driver's probe callback, the supplier's PM-runtime usage
counter will be nonzero after that which effectively causes the
supplier to remain "always on" going forward.

Namely, device_link_add() called to add the link invokes
device_link_rpm_prepare() which notices that the consumer driver is
probing, so it increments the supplier's PM-runtime usage counter
with the assumption that the link will stay around until
pm_runtime_put_suppliers() is called by driver_probe_device(),
but if the link goes away before that point, the supplier's
PM-runtime usage counter will remain nonzero.

To prevent that from happening, first rework pm_runtime_get_suppliers()
and pm_runtime_put_suppliers() to use the rpm_active refounts of device
links and make the latter only drop rpm_active and the supplier's
PM-runtime usage counter for each link by one, unless rpm_active is
one already for it.  Next, modify device_link_add() to bump up the
new link's rpm_active refcount and the suppliers PM-runtime usage
counter by two, to prevent pm_runtime_put_suppliers(), if it is
called subsequently, from suspending the supplier prematurely (in
case its PM-runtime usage counter goes down to 0 in there).

Due to the way rpm_put_suppliers() works, this change does not
affect runtime suspend of the consumer ends of new device links (or,
generally, device links for which DL_FLAG_PM_RUNTIME has just been
set).

Fixes: e2f3cd831a ("driver core: Fix handling of runtime PM flags in device_link_add()")
Reported-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-13 09:09:57 +01:00
..
acpi Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-12-26 17:03:51 -08:00
asm-generic Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
clocksource
crypto crypto: skcipher - remove remnants of internal IV generators 2018-12-23 11:52:45 +08:00
drm i915/snd_hdac: I915 subcomponent for the snd_hdac 2019-02-08 16:58:59 +01:00
dt-bindings ARM: SoC fixes for linux-5.0 2019-02-08 16:23:41 -08:00
keys
kvm KVM: arm/arm64: Remove arch timer workqueue 2018-12-19 17:47:07 +00:00
linux driver core: Fix possible supplier PM-usage counter imbalance 2019-02-13 09:09:57 +01:00
math-emu
media media fixes for v4.20-rc8 2018-12-25 13:11:30 -08:00
memory
misc
net netfilter: nf_tables: unbind set in rule from commit path 2019-02-04 17:29:17 +01:00
pcmcia
ras
rdma RDMA/device: Expose ib_device_try_get(() 2019-01-21 14:33:08 -07:00
scsi 4.21 merge window pull request 2018-12-28 14:57:10 -08:00
soc ARM: SoC driver updates 2018-12-31 17:32:35 -08:00
sound typed componented support + i915/snd-hda changes 2019-02-11 20:32:31 +01:00
target
trace afs: Fix race in async call refcounting 2019-01-17 15:17:28 +00:00
uapi virtio: fixes 2019-02-07 08:05:28 +00:00
video
xen arm64/xen: fix xen-swiotlb cache flushing 2019-01-23 22:14:56 +01:00