diff options
authorAdrian Hunter <adrian.hunter@intel.com>2021-03-26 12:56:19 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2021-03-29 19:27:09 +0200
commit9dfacc54a8661bc8be6e08cffee59596ec59f263 (patch)
parentc0c33442f7203704aef345647e14c2fb86071001 (diff)
PM: runtime: Fix race getting/putting suppliers at probe
pm_runtime_put_suppliers() must not decrement rpm_active unless the consumer is suspended. That is because, otherwise, it could suspend suppliers for an active consumer. That can happen as follows: static int driver_probe_device(struct device_driver *drv, struct device *dev) { int ret = 0; if (!device_is_registered(dev)) return -ENODEV; dev->can_match = true; pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); pm_runtime_get_suppliers(dev); if (dev->parent) pm_runtime_get_sync(dev->parent); At this point, dev can runtime suspend so rpm_put_suppliers() can run, rpm_active becomes 1 (the lowest value). pm_runtime_barrier(dev); if (initcall_debug) ret = really_probe_debug(dev, drv); else ret = really_probe(dev, drv); Probe callback can have runtime resumed dev, and then runtime put so dev is awaiting autosuspend, but rpm_active is 2. pm_request_idle(dev); if (dev->parent) pm_runtime_put(dev->parent); pm_runtime_put_suppliers(dev); Now pm_runtime_put_suppliers() will put the supplier i.e. rpm_active 2 -> 1, but consumer can still be active. return ret; } Fix by checking the runtime status. For any status other than RPM_SUSPENDED, rpm_active can be considered to be "owned" by rpm_[get/put]_suppliers() and pm_runtime_put_suppliers() need do nothing. Reported-by: Asutosh Das <asutoshd@codeaurora.org> Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: 5.1+ <stable@vger.kernel.org> # 5.1+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 4fde37713c58..fe1dad68aee4 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1704,6 +1704,8 @@ void pm_runtime_get_suppliers(struct device *dev)
void pm_runtime_put_suppliers(struct device *dev)
struct device_link *link;
+ unsigned long flags;
+ bool put;
int idx;
idx = device_links_read_lock();
@@ -1712,7 +1714,11 @@ void pm_runtime_put_suppliers(struct device *dev)
if (link->supplier_preactivated) {
link->supplier_preactivated = false;
- if (refcount_dec_not_one(&link->rpm_active))
+ spin_lock_irqsave(&dev->power.lock, flags);
+ put = pm_runtime_status_suspended(dev) &&
+ refcount_dec_not_one(&link->rpm_active);
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+ if (put)

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