linux-kernel - [PATCH RFC RFT 1/3] clk: per-user clk prepare & enable ref counts

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: <1438974570-20812-2-git-send-email-mturquette@baylibre.com>
Date:	Fri,  7 Aug 2015 12:09:28 -0700
From:	Michael Turquette <mturquette@...libre.com>
To:	linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org
Cc:	sboyd@...eaurora.org, lee.jones@...aro.org,
	maxime.ripard@...e-electrons.com, s.hauer@...gutronix.de,
	geert@...ux-m68k.org, Michael Turquette <mturquette@...libre.com>
Subject: [PATCH RFC RFT 1/3] clk: per-user clk prepare & enable ref counts

This patch adds prepare and enable reference counts for the per-user
handles that clock consumers have for a clock node. This patch warns if
an imbalance occurs while trying to disable or unprepare a clock and
aborts, leaving the hardware unaffected.

Signed-off-by: Michael Turquette <mturquette@...libre.com>
---
 drivers/clk/clk.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 898052e..72feee9 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -84,6 +84,8 @@ struct clk {
 	unsigned long min_rate;
 	unsigned long max_rate;
 	struct hlist_node clks_node;
+	unsigned int enable_count;
+	unsigned int prepare_count;
 };
 
 /***           locking             ***/
@@ -600,6 +602,9 @@ void clk_unprepare(struct clk *clk)
 		return;
 
 	clk_prepare_lock();
+	if (WARN_ON(clk->prepare_count == 0))
+		return;
+	clk->prepare_count--;
 	clk_core_unprepare(clk->core);
 	clk_prepare_unlock();
 }
@@ -657,6 +662,7 @@ int clk_prepare(struct clk *clk)
 		return 0;
 
 	clk_prepare_lock();
+	clk->prepare_count++;
 	ret = clk_core_prepare(clk->core);
 	clk_prepare_unlock();
 
@@ -707,6 +713,9 @@ void clk_disable(struct clk *clk)
 		return;
 
 	flags = clk_enable_lock();
+	if (WARN_ON(clk->enable_count == 0))
+		return;
+	clk->enable_count--;
 	clk_core_disable(clk->core);
 	clk_enable_unlock(flags);
 }
@@ -769,6 +778,7 @@ int clk_enable(struct clk *clk)
 		return 0;
 
 	flags = clk_enable_lock();
+	clk->enable_count++;
 	ret = clk_core_enable(clk->core);
 	clk_enable_unlock(flags);
 
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/