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Commit d2a5d46b authored by Dong Aisheng's avatar Dong Aisheng Committed by Stephen Boyd
Browse files

clk: add missing lock when call clk_core_enable in clk_set_parent 



Before commit 035a61c3 ("clk: Make clk API return per-user
struct clk instances") we acquired the enable_lock in
__clk_set_parent_{before,after}() by means of calling
clk_enable(). After commit 035a61c3 we use clk_core_enable()
in place of the clk_enable(), and clk_core_enable() doesn't
acquire the enable_lock. This opens up a race condition between
clk_set_parent() and clk_enable(). Fix it.

Fixes: 035a61c3 ("clk: Make clk API return per-user struct clk instances")
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarDong Aisheng <aisheng.dong@freescale.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent 5d45ed8f

drivers/clk/clk.c

+8 −0
Original line number Diff line number Diff line
@@ -1475,8 +1475,10 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *clk, 
	 */

	if (clk->prepare_count) {

		clk_core_prepare(parent);

		flags = clk_enable_lock();

		clk_core_enable(parent);

		clk_core_enable(clk);

		clk_enable_unlock(flags);

	}



	/* update the clk tree topology */
@@ -1491,13 +1493,17 @@ static void __clk_set_parent_after(struct clk_core *core, 
				   struct clk_core *parent,

				   struct clk_core *old_parent)

{

	unsigned long flags;



	/*

	 * Finish the migration of prepare state and undo the changes done

	 * for preventing a race with clk_enable().

	 */

	if (core->prepare_count) {

		flags = clk_enable_lock();

		clk_core_disable(core);

		clk_core_disable(old_parent);

		clk_enable_unlock(flags);

		clk_core_unprepare(old_parent);

	}

}
@@ -1525,8 +1531,10 @@ static int __clk_set_parent(struct clk_core *clk, struct clk_core *parent, 
		clk_enable_unlock(flags);



		if (clk->prepare_count) {

			flags = clk_enable_lock();

			clk_core_disable(clk);

			clk_core_disable(parent);

			clk_enable_unlock(flags);

			clk_core_unprepare(parent);

		}

		return ret;