From: Saravana Kannan <saravanak@google.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Saravana Kannan <saravanak@google.com>
Cc: Michael Walle <michael@walle.cc>,
kernel-team@android.com,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v3] driver core: Update device link status correctly for SYNC_STATE_ONLY links
Date: Tue, 26 May 2020 15:09:27 -0700 [thread overview]
Message-ID: <20200526220928.49939-1-saravanak@google.com> (raw)
In-Reply-To: <6144404cb26d1f797fd7e87b124bcaf8@walle.cc>
When SYNC_STATE_ONLY support was added in commit 05ef983e0d65 ("driver
core: Add device link support for SYNC_STATE_ONLY flag"),
SYNC_STATE_ONLY links were treated similar to STATELESS links in terms
of not blocking consumer probe if the supplier hasn't probed yet.
That caused a SYNC_STATE_ONLY device link's status to not get updated.
Since SYNC_STATE_ONLY device link is no longer useful once the
consumer probes, commit 21c27f06587d ("driver core: Fix
SYNC_STATE_ONLY device link implementation") addresses the status
update issue by deleting the SYNC_STATE_ONLY device link instead of
complicating the status update code.
However, there are still some cases where we need to update the status
of a SYNC_STATE_ONLY device link. This is because a SYNC_STATE_ONLY
device link can later get converted into a normal MANAGED device link
when a normal MANAGED device link is created between a supplier and
consumer that already have a SYNC_STATE_ONLY device link between them.
If a SYNC_STATE_ONLY device link's status isn't maintained correctly
till it's converted to a normal MANAGED device link, then the normal
MANAGED device link will end up with a wrong link status. This can cause
a warning stack trace[1] when the consumer device probes successfully.
This commit fixes the SYNC_STATE_ONLY device link status update issue
where it wouldn't transition correctly from DL_STATE_DORMANT or
DL_STATE_AVAILABLE to DL_STATE_CONSUMER_PROBE. It also resets the status
back to DL_STATE_DORMANT or DL_STATE_AVAILABLE if the consumer probe
fails.
[1] - https://lore.kernel.org/lkml/20200522204120.3b3c9ed6@apollo/
Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag")
Fixes: 21c27f06587d ("driver core: Fix SYNC_STATE_ONLY device link implementation")
Reported-by: Michael Walle <michael@walle.cc>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
v1->v2:
- Added code to "revert" the link status if consumer probe fails
v2->v3:
- Fixed copy-pasta where I was checking link->status instead of
link->flags.
drivers/base/core.c | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 791b7530599f..9a76dd44cb37 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -646,9 +646,17 @@ static void device_links_missing_supplier(struct device *dev)
{
struct device_link *link;
- list_for_each_entry(link, &dev->links.suppliers, c_node)
- if (link->status == DL_STATE_CONSUMER_PROBE)
+ list_for_each_entry(link, &dev->links.suppliers, c_node) {
+ if (link->status != DL_STATE_CONSUMER_PROBE)
+ continue;
+
+ if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+ } else {
+ WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+ WRITE_ONCE(link->status, DL_STATE_DORMANT);
+ }
+ }
}
/**
@@ -687,11 +695,11 @@ int device_links_check_suppliers(struct device *dev)
device_links_write_lock();
list_for_each_entry(link, &dev->links.suppliers, c_node) {
- if (!(link->flags & DL_FLAG_MANAGED) ||
- link->flags & DL_FLAG_SYNC_STATE_ONLY)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
- if (link->status != DL_STATE_AVAILABLE) {
+ if (link->status != DL_STATE_AVAILABLE &&
+ !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
device_links_missing_supplier(dev);
ret = -EPROBE_DEFER;
break;
@@ -952,11 +960,21 @@ static void __device_links_no_driver(struct device *dev)
if (!(link->flags & DL_FLAG_MANAGED))
continue;
- if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
+ if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
device_link_drop_managed(link);
- else if (link->status == DL_STATE_CONSUMER_PROBE ||
- link->status == DL_STATE_ACTIVE)
+ continue;
+ }
+
+ if (link->status != DL_STATE_CONSUMER_PROBE &&
+ link->status != DL_STATE_ACTIVE)
+ continue;
+
+ if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+ } else {
+ WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+ WRITE_ONCE(link->status, DL_STATE_DORMANT);
+ }
}
dev->links.status = DL_DEV_NO_DRIVER;
--
2.27.0.rc0.183.gde8f92d652-goog
next prev parent reply other threads:[~2020-05-26 22:09 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-16 8:07 [PATCH v1] driver core: Fix memory leak when adding SYNC_STATE_ONLY device links Saravana Kannan
2020-05-18 7:48 ` Saravana Kannan
2020-05-18 8:03 ` Greg Kroah-Hartman
2020-05-18 19:47 ` Saravana Kannan
2020-05-19 3:00 ` [PATCH v2] driver core: Fix SYNC_STATE_ONLY device link implementation Saravana Kannan
2020-05-19 5:48 ` Greg Kroah-Hartman
2020-05-19 6:30 ` [PATCH v3] " Saravana Kannan
2020-05-19 10:47 ` Rafael J. Wysocki
2020-05-22 18:41 ` Michael Walle
2020-05-22 22:21 ` Saravana Kannan
2020-05-22 22:47 ` Michael Walle
2020-05-25 11:31 ` Michael Walle
2020-05-25 18:39 ` Saravana Kannan
2020-05-25 19:04 ` Michael Walle
2020-05-25 21:24 ` Saravana Kannan
2020-05-25 21:38 ` Michael Walle
2020-05-26 7:05 ` [PATCH v1] driver core: Update device link status correctly for SYNC_STATE_ONLY links Saravana Kannan
2020-05-26 7:07 ` Saravana Kannan
2020-05-26 11:04 ` Michael Walle
2020-05-26 18:08 ` Saravana Kannan
2020-05-26 8:28 ` Rafael J. Wysocki
2020-05-26 19:43 ` [PATCH v2] " Saravana Kannan
2020-05-26 21:13 ` Michael Walle
2020-05-26 21:45 ` Saravana Kannan
2020-05-26 21:53 ` Michael Walle
2020-05-26 22:00 ` Saravana Kannan
2020-05-26 22:09 ` Saravana Kannan [this message]
2020-05-27 8:26 ` [PATCH v3] " Rafael J. Wysocki
2020-05-28 16:09 ` Saravana Kannan
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=20200526220928.49939-1-saravanak@google.com \
--to=saravanak@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=kernel-team@android.com \
--cc=linux-kernel@vger.kernel.org \
--cc=michael@walle.cc \
--cc=rafael.j.wysocki@intel.com \
--cc=rafael@kernel.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).