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Subject[PATCH 9/9] clk: Overwrite clk_hw::init with NULL during clk_register()
Date
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>
---

Please ack so I can take this through clk tree

drivers/clk/clk.c | 24 ++++++++++++++++--------
include/linux/clk-provider.h | 3 ++-
2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index c0990703ce54..efac620264a2 100644
--- 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 2ae7604783dd..214c75ed62ae 100644
--- 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;
--
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