linux-kernel - [PATCH v5 2/3] driver core: Add FWLINK_FLAG_IGNORE to completely ignore a fwnode link

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Mon,  4 Mar 2024 21:04:55 -0800
From: Saravana Kannan <saravanak@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Ard Biesheuvel <ardb@...nel.org>, Rob Herring <robh+dt@...nel.org>, 
	Frank Rowand <frowand.list@...il.com>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Daniel Scally <djrscally@...il.com>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, Len Brown <lenb@...nel.org>
Cc: Saravana Kannan <saravanak@...gle.com>, kernel-team@...roid.com, 
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-acpi@...r.kernel.org, 
	Rob Herring <robh@...nel.org>
Subject: [PATCH v5 2/3] driver core: Add FWLINK_FLAG_IGNORE to completely
 ignore a fwnode link

A fwnode link between specific supplier-consumer fwnodes can be added
multiple times for multiple reasons. If that dependency doesn't exist,
deleting the fwnode link once doesn't guarantee that it won't get created
again.

So, add FWLINK_FLAG_IGNORE flag to mark a fwnode link as one that needs to
be completely ignored. Since a fwnode link's flags is an OR of all the
flags passed to all the fwnode_link_add() calls to create that specific
fwnode link, the FWLINK_FLAG_IGNORE flag is preserved and can be used to
mark a fwnode link as on that need to be completely ignored until it is
deleted.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
Acked-by: Rafael J. Wysocki <rafael@...nel.org>
Reviewed-by: Rob Herring <robh@...nel.org>
---
 drivers/base/core.c    | 9 ++++++++-
 include/linux/fwnode.h | 2 ++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index adeff041d472..fac017657d25 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1012,7 +1012,8 @@ static struct fwnode_handle *fwnode_links_check_suppliers(
 		return NULL;
 
 	list_for_each_entry(link, &fwnode->suppliers, c_hook)
-		if (!(link->flags & FWLINK_FLAG_CYCLE))
+		if (!(link->flags &
+		      (FWLINK_FLAG_CYCLE | FWLINK_FLAG_IGNORE)))
 			return link->supplier;
 
 	return NULL;
@@ -1963,6 +1964,9 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 	}
 
 	list_for_each_entry(link, &sup_handle->suppliers, c_hook) {
+		if (link->flags & FWLINK_FLAG_IGNORE)
+			continue;
+
 		if (__fw_devlink_relax_cycles(con, link->supplier)) {
 			__fwnode_link_cycle(link);
 			ret = true;
@@ -2041,6 +2045,9 @@ static int fw_devlink_create_devlink(struct device *con,
 	int ret = 0;
 	u32 flags;
 
+	if (link->flags & FWLINK_FLAG_IGNORE)
+		return 0;
+
 	if (con->fwnode == link->consumer)
 		flags = fw_devlink_get_flags(link->flags);
 	else
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index c964749953e3..21699eee9641 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -53,8 +53,10 @@ struct fwnode_handle {
  * fwnode link flags
  *
  * CYCLE:	The fwnode link is part of a cycle. Don't defer probe.
+ * IGNORE:	Completely ignore this link, even during cycle detection.
  */
 #define FWLINK_FLAG_CYCLE			BIT(0)
+#define FWLINK_FLAG_IGNORE			BIT(1)
 
 struct fwnode_link {
 	struct fwnode_handle *supplier;
-- 
2.44.0.278.ge034bb2e1d-goog