clk: add missing lock when call clk_core_enable in clk_set_parent

Before commit 035a61c314eb ("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 035a61c314eb 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: 035a61c314eb ("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: Dong Aisheng <aisheng.dong@freescale.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 459ce9da13e0631b41e6cafc5ed9a85523e5e1b7..5b0f41868b425672e6295ac6b30a52e43cf5730c 100644 (file)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -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;