linux-kernel - [PATCH v2 1/4] clk: Don't cache errors from clk_ops::get

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: <20200205232802.29184-2-sboyd@kernel.org>
Date:   Wed,  5 Feb 2020 15:27:59 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Jerome Brunet <jbrunet@...libre.com>
Subject: [PATCH v2 1/4] clk: Don't cache errors from clk_ops::get_phase()

We don't check for errors from clk_ops::get_phase() before storing away
the result into the clk_core::phase member. This can lead to some fairly
confusing debugfs information if these ops do return an error. Let's
skip the store when this op fails to fix this. While we're here, move
the locking outside of clk_core_get_phase() to simplify callers from
the debugfs side.

Cc: Douglas Anderson <dianders@...omium.org>
Cc: Heiko Stuebner <heiko@...ech.de>
Cc: Jerome Brunet <jbrunet@...libre.com>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
---
 drivers/clk/clk.c | 48 +++++++++++++++++++++++++++++++----------------
 1 file changed, 32 insertions(+), 16 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index d529ad67805c..26213e82f5f9 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2660,12 +2660,14 @@ static int clk_core_get_phase(struct clk_core *core)
 {
 	int ret;
 
-	clk_prepare_lock();
+	lockdep_assert_held(&prepare_lock);
+	if (!core->ops->get_phase)
+		return 0;
+
 	/* Always try to update cached phase if possible */
-	if (core->ops->get_phase)
-		core->phase = core->ops->get_phase(core->hw);
-	ret = core->phase;
-	clk_prepare_unlock();
+	ret = core->ops->get_phase(core->hw);
+	if (ret >= 0)
+		core->phase = ret;
 
 	return ret;
 }
@@ -2679,10 +2681,16 @@ static int clk_core_get_phase(struct clk_core *core)
  */
 int clk_get_phase(struct clk *clk)
 {
+	int ret;
+
 	if (!clk)
 		return 0;
 
-	return clk_core_get_phase(clk->core);
+	clk_prepare_lock();
+	ret = clk_core_get_phase(clk->core);
+	clk_prepare_unlock();
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(clk_get_phase);
 
@@ -2896,13 +2904,21 @@ static struct hlist_head *orphan_list[] = {
 static void clk_summary_show_one(struct seq_file *s, struct clk_core *c,
 				 int level)
 {
-	seq_printf(s, "%*s%-*s %7d %8d %8d %11lu %10lu %5d %6d\n",
+	int phase;
+
+	seq_printf(s, "%*s%-*s %7d %8d %8d %11lu %10lu ",
 		   level * 3 + 1, "",
 		   30 - level * 3, c->name,
 		   c->enable_count, c->prepare_count, c->protect_count,
-		   clk_core_get_rate(c), clk_core_get_accuracy(c),
-		   clk_core_get_phase(c),
-		   clk_core_get_scaled_duty_cycle(c, 100000));
+		   clk_core_get_rate(c), clk_core_get_accuracy(c));
+
+	phase = clk_core_get_phase(c);
+	if (phase >= 0)
+		seq_printf(s, "%5d", phase);
+	else
+		seq_puts(s, "-----");
+
+	seq_printf(s, " %6d\n", clk_core_get_scaled_duty_cycle(c, 100000));
 }
 
 static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
@@ -2939,6 +2955,7 @@ DEFINE_SHOW_ATTRIBUTE(clk_summary);
 
 static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
 {
+	int phase;
 	unsigned long min_rate, max_rate;
 
 	clk_core_get_boundaries(c, &min_rate, &max_rate);
@@ -2952,7 +2969,9 @@ static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
 	seq_printf(s, "\"min_rate\": %lu,", min_rate);
 	seq_printf(s, "\"max_rate\": %lu,", max_rate);
 	seq_printf(s, "\"accuracy\": %lu,", clk_core_get_accuracy(c));
-	seq_printf(s, "\"phase\": %d,", clk_core_get_phase(c));
+	phase = clk_core_get_phase(c);
+	if (phase >= 0)
+		seq_printf(s, "\"phase\": %d,", phase);
 	seq_printf(s, "\"duty_cycle\": %u",
 		   clk_core_get_scaled_duty_cycle(c, 100000));
 }
@@ -3434,14 +3453,11 @@ static int __clk_core_init(struct clk_core *core)
 		core->accuracy = 0;
 
 	/*
-	 * Set clk's phase.
+	 * Set clk's phase by clk_core_get_phase() caching the phase.
 	 * Since a phase is by definition relative to its parent, just
 	 * query the current clock phase, or just assume it's in phase.
 	 */
-	if (core->ops->get_phase)
-		core->phase = core->ops->get_phase(core->hw);
-	else
-		core->phase = 0;
+	clk_core_get_phase(core);
 
 	/*
 	 * Set clk's duty cycle.
-- 
Sent by a computer, using git, on the internet