clk: Overwrite clk_hw::init with NULL during clk_register()

We don't want clk provider drivers to use the init structure after clk
registration time, but we leave a dangling reference to it by means of
clk_hw::init. Let's overwrite the member with NULL during clk_register()
so that this can't be used anymore after registration time.

Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Doug Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20190731193517.237136-10-sboyd@kernel.org
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index c099070..efac620 100644 (file)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3484,9 +3484,9 @@ static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist)
        return 0;
 }
 
-static int clk_core_populate_parent_map(struct clk_core *core)
+static int clk_core_populate_parent_map(struct clk_core *core,
+                                       const struct clk_init_data *init)
 {
-       const struct clk_init_data *init = core->hw->init;
        u8 num_parents = init->num_parents;
        const char * const *parent_names = init->parent_names;
        const struct clk_hw **parent_hws = init->parent_hws;
@@ -3566,6 +3566,14 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
 {
        int ret;
        struct clk_core *core;
+       const struct clk_init_data *init = hw->init;
+
+       /*
+        * The init data is not supposed to be used outside of registration path.
+        * Set it to NULL so that provider drivers can't use it either and so that
+        * we catch use of hw->init early on in the core.
+        */
+       hw->init = NULL;
 
        core = kzalloc(sizeof(*core), GFP_KERNEL);
        if (!core) {
@@ -3573,17 +3581,17 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
                goto fail_out;
        }
 
-       core->name = kstrdup_const(hw->init->name, GFP_KERNEL);
+       core->name = kstrdup_const(init->name, GFP_KERNEL);
        if (!core->name) {
                ret = -ENOMEM;
                goto fail_name;
        }
 
-       if (WARN_ON(!hw->init->ops)) {
+       if (WARN_ON(!init->ops)) {
                ret = -EINVAL;
                goto fail_ops;
        }
-       core->ops = hw->init->ops;
+       core->ops = init->ops;
 
        if (dev && pm_runtime_enabled(dev))
                core->rpm_enabled = true;
@@ -3592,13 +3600,13 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
        if (dev && dev->driver)
                core->owner = dev->driver->owner;
        core->hw = hw;
-       core->flags = hw->init->flags;
-       core->num_parents = hw->init->num_parents;
+       core->flags = init->flags;
+       core->num_parents = init->num_parents;
        core->min_rate = 0;
        core->max_rate = ULONG_MAX;
        hw->core = core;
 
-       ret = clk_core_populate_parent_map(core);
+       ret = clk_core_populate_parent_map(core, init);
        if (ret)
                goto fail_parents;
 

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 2ae7604..214c75e 100644 (file)
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -299,7 +299,8 @@ struct clk_init_data {
  * into the clk API
  *
  * @init: pointer to struct clk_init_data that contains the init data shared
- * with the common clock framework.
+ * with the common clock framework. This pointer will be set to NULL once
+ * a clk_register() variant is called on this clk_hw pointer.
  */
 struct clk_hw {
        struct clk_core *core;