From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Jon Hunter <jonathanh@nvidia.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
Thierry Reding <treding@nvidia.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
linux-pm@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 205/671] driver core: Fix PM-runtime for links added during consumer probe
Date: Thu, 16 Jan 2020 11:51:54 -0500 [thread overview]
Message-ID: <20200116165940.10720-88-sashal@kernel.org> (raw)
In-Reply-To: <20200116165940.10720-1-sashal@kernel.org>
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
[ Upstream commit 36003d4cf57ca431fb3f94d317bcca426a2394d6 ]
Commit 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage
counter imbalance") introduced a regression that causes suppliers
to be suspended prematurely for device links added during consumer
driver probe if the initial PM-runtime status of the consumer is
"suspended" and the consumer is resumed after adding the link and
before pm_runtime_put_suppliers() is called. In that case,
pm_runtime_put_suppliers() will drop the rpm_active refcount for
the link by one and (since rpm_active is equal to two after the
preceding consumer resume) the supplier's PM-runtime usage counter
will be decremented, which may cause the supplier to suspend even
though the consumer's PM-runtime status is "active".
For this reason, partially revert commit 4c06c4e6cf63 as the problem
it tried to fix needs to be addressed somewhat differently, and
change pm_runtime_get_suppliers() and pm_runtime_put_suppliers() so
that the latter only drops rpm_active references acquired by the
former. [This requires adding a new field to struct device_link,
but I coulnd't find a cleaner way to address the issue that would
work in all cases.]
This causes pm_runtime_put_suppliers() to effectively ignore device
links added during consumer probe, so device_link_add() doesn't need
to worry about ensuring that suppliers will remain active after
pm_runtime_put_suppliers() for links created with DL_FLAG_RPM_ACTIVE
set and it only needs to bump up rpm_active by one for those links,
so pm_runtime_active_link() is not necessary any more.
Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/base/core.c | 4 ++--
drivers/base/power/runtime.c | 29 ++++++-----------------------
include/linux/device.h | 1 +
include/linux/pm_runtime.h | 4 ----
4 files changed, 9 insertions(+), 29 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ab08211ba5d2..742bc60e9cca 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -253,7 +253,7 @@ struct device_link *device_link_add(struct device *consumer,
link->flags |= DL_FLAG_PM_RUNTIME;
}
if (flags & DL_FLAG_RPM_ACTIVE)
- pm_runtime_active_link(link, supplier);
+ refcount_inc(&link->rpm_active);
}
kref_get(&link->kref);
@@ -268,7 +268,7 @@ struct device_link *device_link_add(struct device *consumer,
if (flags & DL_FLAG_PM_RUNTIME) {
if (flags & DL_FLAG_RPM_ACTIVE)
- pm_runtime_active_link(link, supplier);
+ refcount_inc(&link->rpm_active);
pm_runtime_new_link(consumer);
}
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 0527890b4c19..303ce7d54a30 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1571,6 +1571,7 @@ void pm_runtime_get_suppliers(struct device *dev)
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
if (link->flags & DL_FLAG_PM_RUNTIME) {
+ link->supplier_preactivated = true;
refcount_inc(&link->rpm_active);
pm_runtime_get_sync(link->supplier);
}
@@ -1590,9 +1591,11 @@ void pm_runtime_put_suppliers(struct device *dev)
idx = device_links_read_lock();
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
- if (link->flags & DL_FLAG_PM_RUNTIME &&
- refcount_dec_not_one(&link->rpm_active))
- pm_runtime_put(link->supplier);
+ if (link->supplier_preactivated) {
+ link->supplier_preactivated = false;
+ if (refcount_dec_not_one(&link->rpm_active))
+ pm_runtime_put(link->supplier);
+ }
device_links_read_unlock(idx);
}
@@ -1604,26 +1607,6 @@ void pm_runtime_new_link(struct device *dev)
spin_unlock_irq(&dev->power.lock);
}
-/**
- * pm_runtime_active_link - Set up new device link as active for PM-runtime.
- * @link: Device link to be set up as active.
- * @supplier: Supplier end of the link.
- *
- * Add 2 to the rpm_active refcount of @link and increment the PM-runtime
- * usage counter of @supplier once more in case the link is being added while
- * the consumer driver is probing and pm_runtime_put_suppliers() will be called
- * subsequently.
- *
- * Note that this doesn't prevent rpm_put_suppliers() from decreasing the link's
- * rpm_active refcount down to one, so runtime suspend of the consumer end of
- * @link is not affected.
- */
-void pm_runtime_active_link(struct device_link *link, struct device *supplier)
-{
- refcount_add(2, &link->rpm_active);
- pm_runtime_get_noresume(supplier);
-}
-
void pm_runtime_drop_link(struct device *dev)
{
spin_lock_irq(&dev->power.lock);
diff --git a/include/linux/device.h b/include/linux/device.h
index b8fd2a1f859d..e9d1c768f972 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -854,6 +854,7 @@ struct device_link {
#ifdef CONFIG_SRCU
struct rcu_head rcu_head;
#endif
+ bool supplier_preactivated; /* Owned by consumer probe. */
};
/**
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index bace7df51af4..f0fc4700b6ff 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -59,8 +59,6 @@ extern void pm_runtime_clean_up_links(struct device *dev);
extern void pm_runtime_get_suppliers(struct device *dev);
extern void pm_runtime_put_suppliers(struct device *dev);
extern void pm_runtime_new_link(struct device *dev);
-extern void pm_runtime_active_link(struct device_link *link,
- struct device *supplier);
extern void pm_runtime_drop_link(struct device *dev);
static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
@@ -178,8 +176,6 @@ static inline void pm_runtime_clean_up_links(struct device *dev) {}
static inline void pm_runtime_get_suppliers(struct device *dev) {}
static inline void pm_runtime_put_suppliers(struct device *dev) {}
static inline void pm_runtime_new_link(struct device *dev) {}
-static inline void pm_runtime_active_link(struct device_link *link,
- struct device *supplier) {}
static inline void pm_runtime_drop_link(struct device *dev) {}
#endif /* !CONFIG_PM */
--
2.20.1
next prev parent reply other threads:[~2020-01-16 19:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200116165940.10720-1-sashal@kernel.org>
2020-01-16 16:50 ` [PATCH AUTOSEL 4.19 145/671] driver core: Fix handling of runtime PM flags in device_link_add() Sasha Levin
2020-01-16 16:50 ` [PATCH AUTOSEL 4.19 146/671] driver core: Do not call rpm_put_suppliers() in pm_runtime_drop_link() Sasha Levin
2020-01-16 16:51 ` [PATCH AUTOSEL 4.19 157/671] thermal: mediatek: fix register index error Sasha Levin
2020-01-16 16:51 ` [PATCH AUTOSEL 4.19 179/671] driver core: Fix possible supplier PM-usage counter imbalance Sasha Levin
2020-01-16 16:51 ` Sasha Levin [this message]
2020-01-16 16:52 ` [PATCH AUTOSEL 4.19 220/671] ARM: 8847/1: pm: fix HYP/SVC mode mismatch when MCPM is used Sasha Levin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200116165940.10720-88-sashal@kernel.org \
--to=sashal@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=jonathanh@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rafael.j.wysocki@intel.com \
--cc=stable@vger.kernel.org \
--cc=treding@nvidia.com \
--cc=ulf.hansson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).