linux-kernel - [PATCH 1/2] clk: Fix the CLK_IGNORE

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]

Message-Id: <20240929-fix_glitch_free-v1-1-22f9c36b7edf@amlogic.com>
Date: Sun, 29 Sep 2024 14:10:05 +0800
From: Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org>
To: Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>, 
 Jerome Brunet <jbrunet@...libre.com>, Kevin Hilman <khilman@...libre.com>, 
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-amlogic@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, 
 Chuan Liu <chuan.liu@...ogic.com>
Subject: [PATCH 1/2] clk: Fix the CLK_IGNORE_UNUSED failure issue

From: Chuan Liu <chuan.liu@...ogic.com>

When the clk_disable_unused_subtree() function disables an unused clock,
if CLK_OPS_PARENT_ENABLE is configured on the clock,
clk_core_prepare_enable() and clk_core_disable_unprepare() are called
directly, and these two functions do not determine CLK_IGNORE_UNUSED,
This causes the clock to be disabled even if CLK_IGNORE_UNUSED is
configured when clk_core_disable_unprepare() is called.

Two new functions clk_disable_unprepare_unused() and
clk_prepare_enable_unused() are added to resolve the preceding
situation. The CLK_IGNORE_UNUSED judgment logic is added to these two
functions. To prevent clock configuration CLK_IGNORE_UNUSED from
possible failure.

Change-Id: I56943e17b86436254f07d9b8cdbc35599328d519
Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>
---
 drivers/clk/clk.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 285ed1ad8a37..5d3316699b57 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -94,6 +94,7 @@ struct clk_core {
 	struct hlist_node	debug_node;
 #endif
 	struct kref		ref;
+	bool			ignore_enabled;
 };
 
 #define CREATE_TRACE_POINTS
@@ -1479,6 +1480,68 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
 	}
 }
 
+static void __init clk_disable_unprepare_unused(struct clk_core *core)
+{
+	unsigned long flags;
+
+	lockdep_assert_held(&prepare_lock);
+
+	if (!core)
+		return;
+
+	if ((core->enable_count == 0) && core->ops->disable &&
+	    !core->ignore_enabled) {
+		flags = clk_enable_lock();
+		core->ops->disable(core->hw);
+		clk_enable_unlock(flags);
+	}
+
+	if ((core->prepare_count == 0) && core->ops->unprepare &&
+	    !core->ignore_enabled)
+		core->ops->unprepare(core->hw);
+
+	core->ignore_enabled = false;
+
+	clk_disable_unprepare_unused(core->parent);
+}
+
+static int __init clk_prepare_enable_unused(struct clk_core *core)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	lockdep_assert_held(&prepare_lock);
+
+	if (!core)
+		return 0;
+
+	ret = clk_prepare_enable_unused(core->parent);
+	if (ret)
+		return ret;
+
+	if ((core->flags & CLK_IGNORE_UNUSED) && clk_core_is_enabled(core))
+		core->ignore_enabled = true;
+
+	if ((core->prepare_count == 0) && core->ops->prepare) {
+		ret = core->ops->prepare(core->hw);
+		if (ret)
+			goto disable_unprepare;
+	}
+
+	if ((core->enable_count == 0) && core->ops->enable) {
+		flags = clk_enable_lock();
+		ret = core->ops->enable(core->hw);
+		clk_enable_unlock(flags);
+		if (ret)
+			goto disable_unprepare;
+	}
+
+	return 0;
+disable_unprepare:
+	clk_disable_unprepare_unused(core->parent);
+	return ret;
+}
+
 static void __init clk_disable_unused_subtree(struct clk_core *core)
 {
 	struct clk_core *child;
@@ -1490,7 +1553,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
 		clk_disable_unused_subtree(child);
 
 	if (core->flags & CLK_OPS_PARENT_ENABLE)
-		clk_core_prepare_enable(core->parent);
+		clk_prepare_enable_unused(core->parent);
 
 	flags = clk_enable_lock();
 
@@ -1517,7 +1580,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
 unlock_out:
 	clk_enable_unlock(flags);
 	if (core->flags & CLK_OPS_PARENT_ENABLE)
-		clk_core_disable_unprepare(core->parent);
+		clk_disable_unprepare_unused(core->parent);
 }
 
 static bool clk_ignore_unused __initdata;

-- 
2.42.0