From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>,
"elaine.zhang" <zhangqing@rock-chips.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>
Subject: [PATCH v1 1/2] Revert "PM: runtime: Update device status before letting suppliers suspend"
Date: Thu, 18 Mar 2021 19:09:06 +0100 [thread overview]
Message-ID: <4304785.LvFx2qVVIh@kreacher> (raw)
In-Reply-To: <5448054.DvuYhMxLoT@kreacher>
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Revert commit 44cc89f76464 ("PM: runtime: Update device status
before letting suppliers suspend") that introduced a race condition
into __rpm_callback() which allowed a concurrent rpm_resume() to
run and resume the device prematurely after its status had been
changed to RPM_SUSPENDED by __rpm_callback().
Fixes: 44cc89f76464 ("PM: runtime: Update device status before letting suppliers suspend")
Link: https://lore.kernel.org/linux-pm/24dfb6fc-5d54-6ee2-9195-26428b7ecf8a@intel.com/
Reported by: Adrian Hunter <adrian.hunter@intel.com>
Cc: 4.10+ <stable@vger.kernel.org> # 4.10+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/base/power/runtime.c | 62 +++++++++++++++---------------------
1 file changed, 25 insertions(+), 37 deletions(-)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 18b82427d0cb..a46a7e30881b 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -325,22 +325,22 @@ static void rpm_put_suppliers(struct device *dev)
static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
- bool use_links = dev->power.links_count > 0;
- bool get = false;
int retval, idx;
- bool put;
+ bool use_links = dev->power.links_count > 0;
if (dev->power.irq_safe) {
spin_unlock(&dev->power.lock);
- } else if (!use_links) {
- spin_unlock_irq(&dev->power.lock);
} else {
- get = dev->power.runtime_status == RPM_RESUMING;
-
spin_unlock_irq(&dev->power.lock);
- /* Resume suppliers if necessary. */
- if (get) {
+ /*
+ * Resume suppliers if necessary.
+ *
+ * The device's runtime PM status cannot change until this
+ * routine returns, so it is safe to read the status outside of
+ * the lock.
+ */
+ if (use_links && dev->power.runtime_status == RPM_RESUMING) {
idx = device_links_read_lock();
retval = rpm_get_suppliers(dev);
@@ -355,36 +355,24 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
if (dev->power.irq_safe) {
spin_lock(&dev->power.lock);
- return retval;
- }
-
- spin_lock_irq(&dev->power.lock);
-
- if (!use_links)
- return retval;
-
- /*
- * If the device is suspending and the callback has returned success,
- * drop the usage counters of the suppliers that have been reference
- * counted on its resume.
- *
- * Do that if the resume fails too.
- */
- put = dev->power.runtime_status == RPM_SUSPENDING && !retval;
- if (put)
- __update_runtime_status(dev, RPM_SUSPENDED);
- else
- put = get && retval;
-
- if (put) {
- spin_unlock_irq(&dev->power.lock);
-
- idx = device_links_read_lock();
+ } else {
+ /*
+ * If the device is suspending and the callback has returned
+ * success, drop the usage counters of the suppliers that have
+ * been reference counted on its resume.
+ *
+ * Do that if resume fails too.
+ */
+ if (use_links
+ && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
+ || (dev->power.runtime_status == RPM_RESUMING && retval))) {
+ idx = device_links_read_lock();
-fail:
- rpm_put_suppliers(dev);
+ fail:
+ rpm_put_suppliers(dev);
- device_links_read_unlock(idx);
+ device_links_read_unlock(idx);
+ }
spin_lock_irq(&dev->power.lock);
}
--
2.26.2
next prev parent reply other threads:[~2021-03-18 18:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 18:06 [PATCH v1 0/2] PM: runtime: Update device status before letting suppliers suspend (another take) Rafael J. Wysocki
2021-03-18 18:09 ` Rafael J. Wysocki [this message]
2021-03-19 13:29 ` [PATCH v1 1/2] Revert "PM: runtime: Update device status before letting suppliers suspend" Ulf Hansson
2021-03-19 13:43 ` Rafael J. Wysocki
2021-03-18 18:15 ` [PATCH v1 2/2] PM: runtime: Defer suspending suppliers Rafael J. Wysocki
2021-03-19 13:29 ` Ulf Hansson
2021-03-19 13:48 ` Rafael J. Wysocki
2021-03-19 14:42 ` [PATCH v2 0/2] PM: runtime: Update device status before letting suppliers suspend (another take) Rafael J. Wysocki
2021-03-19 14:47 ` [PATCH v2 1/2] Revert "PM: runtime: Update device status before letting suppliers suspend" Rafael J. Wysocki
2021-03-19 14:47 ` [PATCH v2 2/2] PM: runtime: Defer suspending suppliers Rafael J. Wysocki
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