linux-kernel - [PATCH AUTOSEL 6.8 08/18] clk: Don't hold prepare_lock when calling kref

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: <20240423110118.1652940-8-sashal@kernel.org>
Date: Tue, 23 Apr 2024 07:01:04 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Stephen Boyd <sboyd@...nel.org>,
	Douglas Anderson <dianders@...omium.org>,
	Sasha Levin <sashal@...nel.org>,
	mturquette@...libre.com,
	linux-clk@...r.kernel.org
Subject: [PATCH AUTOSEL 6.8 08/18] clk: Don't hold prepare_lock when calling kref_put()

From: Stephen Boyd <sboyd@...nel.org>

[ Upstream commit 6f63af7511e7058f3fa4ad5b8102210741c9f947 ]

We don't need to hold the prepare_lock when dropping a ref on a struct
clk_core. The release function is only freeing memory and any code with
a pointer reference has already unlinked anything pointing to the
clk_core. This reduces the holding area of the prepare_lock a bit.

Note that we also don't call free_clk() with the prepare_lock held.
There isn't any reason to do that.

Reviewed-by: Douglas Anderson <dianders@...omium.org>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Link: https://lore.kernel.org/r/20240325184204.745706-3-sboyd@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/clk/clk.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 20c4b28fed061..badb6fdf83a2a 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -4453,7 +4453,8 @@ void clk_unregister(struct clk *clk)
 	if (ops == &clk_nodrv_ops) {
 		pr_err("%s: unregistered clock: %s\n", __func__,
 		       clk->core->name);
-		goto unlock;
+		clk_prepare_unlock();
+		return;
 	}
 	/*
 	 * Assign empty clock ops for consumers that might still hold
@@ -4487,11 +4488,10 @@ void clk_unregister(struct clk *clk)
 	if (clk->core->protect_count)
 		pr_warn("%s: unregistering protected clock: %s\n",
 					__func__, clk->core->name);
+	clk_prepare_unlock();
 
 	kref_put(&clk->core->ref, __clk_release);
 	free_clk(clk);
-unlock:
-	clk_prepare_unlock();
 }
 EXPORT_SYMBOL_GPL(clk_unregister);
 
@@ -4650,13 +4650,11 @@ void __clk_put(struct clk *clk)
 	if (clk->min_rate > 0 || clk->max_rate < ULONG_MAX)
 		clk_set_rate_range_nolock(clk, 0, ULONG_MAX);
 
-	owner = clk->core->owner;
-	kref_put(&clk->core->ref, __clk_release);
-
 	clk_prepare_unlock();
 
+	owner = clk->core->owner;
+	kref_put(&clk->core->ref, __clk_release);
 	module_put(owner);
-
 	free_clk(clk);
 }
 
-- 
2.43.0