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From: Stephen Boyd <sboyd@kernel.org>
To: Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
	patches@lists.linux.dev, linux-arm-msm@vger.kernel.org,
	Douglas Anderson <dianders@chromium.org>
Subject: [PATCH v2 2/5] clk: Don't hold prepare_lock when calling kref_put()
Date: Mon, 25 Mar 2024 11:41:56 -0700	[thread overview]
Message-ID: <20240325184204.745706-3-sboyd@kernel.org> (raw)
In-Reply-To: <20240325184204.745706-1-sboyd@kernel.org>

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@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.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 44e71736477d..9fc522c26de8 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -4448,7 +4448,8 @@ 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
@@ -4482,11 +4483,10 @@ 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);
 
@@ -4645,13 +4645,11 @@ 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);
 }
 
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git


  parent reply	other threads:[~2024-03-25 18:42 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-25 18:41 [PATCH v2 0/5] Fix a deadlock with clk_pm_runtime_get() Stephen Boyd
2024-03-25 18:41 ` [PATCH v2 1/5] clk: Remove prepare_lock hold assertion in __clk_release() Stephen Boyd
2024-04-08  2:35   ` Stephen Boyd
2024-03-25 18:41 ` Stephen Boyd [this message]
2024-04-08  2:35   ` [PATCH v2 2/5] clk: Don't hold prepare_lock when calling kref_put() Stephen Boyd
2024-03-25 18:41 ` [PATCH v2 3/5] clk: Initialize struct clk_core kref earlier Stephen Boyd
2024-04-08  2:36   ` Stephen Boyd
2024-03-25 18:41 ` [PATCH v2 4/5] clk: Get runtime PM before walking tree during disable_unused Stephen Boyd
2024-03-25 19:39   ` Doug Anderson
2024-04-08  2:36   ` Stephen Boyd
2024-04-09 10:32     ` Ulf Hansson
2024-04-09 11:55       ` Stephen Boyd
2024-03-25 18:41 ` [PATCH v2 5/5] clk: Get runtime PM before walking tree for clk_summary Stephen Boyd
2024-03-25 19:39   ` Doug Anderson
2024-04-08  2:37   ` Stephen Boyd
2024-03-25 18:44 ` [PATCH v2 0/5] Fix a deadlock with clk_pm_runtime_get() Stephen Boyd

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