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Date: Mon, 16 Apr 2012 22:30:16 +0200
From: Sascha Hauer <s.hauer@...gutronix.de>
To: Mike Turquette <mturquette@...aro.org>
Cc: arnd.bergmann@...aro.org, Andrew Lunn <andrew@...n.ch>,
Rajendra Nayak <rnayak@...com>, patches@...aro.org,
Mark Brown <broonie@...nsource.wolfsonmicro.com>,
linux-kernel@...r.kernel.org,
Russell King <linux@....linux.org.uk>,
Saravana Kannan <skannan@...eaurora.org>,
Shawn Guo <shawn.guo@...escale.com>,
Olof Johansson <olof@...om.net>, linaro-dev@...ts.linaro.org,
Richard Zhao <richard.zhao@...aro.org>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 12/13] clk: core: copy parent_names & return error codes
On Wed, Apr 11, 2012 at 06:02:50PM -0700, Mike Turquette wrote:
> This patch cleans up clk_register and solves a few bugs by teaching
> clk_register and __clk_init to return error codes (instead of just NULL)
> to better align with the existing clk.h api.
>
> Along with that change this patch also introduces a new behavior whereby
> clk_register copies the parent_names array, thus allowing platforms to
> declare their parent_names arrays as __initdata.
>
> Signed-off-by: Mike Turquette <mturquette@...aro.org>
> Cc: Arnd Bergman <arnd.bergmann@...aro.org>
> Cc: Olof Johansson <olof@...om.net>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: Sascha Hauer <s.hauer@...gutronix.de>
> Cc: Shawn Guo <shawn.guo@...escale.com>
> Cc: Richard Zhao <richard.zhao@...aro.org>
> Cc: Saravana Kannan <skannan@...eaurora.org>
> Cc: Mark Brown <broonie@...nsource.wolfsonmicro.com>
> Cc: Andrew Lunn <andrew@...n.ch>
> Cc: Rajendra Nayak <rnayak@...com>
> Cc: Viresh Kumar <viresh.kumar@...com>
> ---
> drivers/clk/clk.c | 61 +++++++++++++++++++++++++++++++++--------
> include/linux/clk-private.h | 4 ++-
> include/linux/clk-provider.h | 3 +-
> 3 files changed, 54 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index ddade87..af2bf12 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1185,34 +1185,41 @@ EXPORT_SYMBOL_GPL(clk_set_parent);
> * very large numbers of clocks that need to be statically initialized. It is
> * a layering violation to include clk-private.h from any code which implements
> * a clock's .ops; as such any statically initialized clock data MUST be in a
> - * separate C file from the logic that implements it's operations.
> + * separate C file from the logic that implements it's operations. Returns 0
> + * on success, otherwise an error code.
> */
> -void __clk_init(struct device *dev, struct clk *clk)
> +int __clk_init(struct device *dev, struct clk *clk)
> {
> - int i;
> + int i, ret = 0;
> struct clk *orphan;
> struct hlist_node *tmp, *tmp2;
>
> if (!clk)
> - return;
> + return -EINVAL;
>
> mutex_lock(&prepare_lock);
>
> /* check to see if a clock with this name is already registered */
> - if (__clk_lookup(clk->name))
> + if (__clk_lookup(clk->name)) {
> + pr_debug("%s: clk %s already initialized\n",
> + __func__, clk->name);
> + ret = -EEXIST;
> goto out;
> + }
>
> /* check that clk_ops are sane. See Documentation/clk.txt */
> if (clk->ops->set_rate &&
> !(clk->ops->round_rate && clk->ops->recalc_rate)) {
> pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
> __func__, clk->name);
> + ret = -EINVAL;
> goto out;
> }
>
> if (clk->ops->set_parent && !clk->ops->get_parent) {
> pr_warning("%s: %s must implement .get_parent & .set_parent\n",
> __func__, clk->name);
> + ret = -EINVAL;
> goto out;
> }
>
> @@ -1308,7 +1315,7 @@ void __clk_init(struct device *dev, struct clk *clk)
> out:
> mutex_unlock(&prepare_lock);
>
> - return;
> + return ret;
> }
>
> /**
> @@ -1324,29 +1331,59 @@ out:
> * clk_register is the primary interface for populating the clock tree with new
> * clock nodes. It returns a pointer to the newly allocated struct clk which
> * cannot be dereferenced by driver code but may be used in conjuction with the
> - * rest of the clock API.
> + * rest of the clock API. In the event of an error clk_register will return an
> + * error code; drivers must test for an error code after calling clk_register.
> */
> struct clk *clk_register(struct device *dev, const char *name,
> const struct clk_ops *ops, struct clk_hw *hw,
> const char **parent_names, u8 num_parents, unsigned long flags)
> {
> + int i, ret = -ENOMEM;
I suggest to move the initialization of ret from here...
> struct clk *clk;
>
> clk = kzalloc(sizeof(*clk), GFP_KERNEL);
> - if (!clk)
> - return NULL;
> + if (!clk) {
> + pr_err("%s: could not allocate clk\n", __func__);
> + goto fail_out;
> + }
>
> clk->name = name;
> clk->ops = ops;
> clk->hw = hw;
> clk->flags = flags;
> - clk->parent_names = parent_names;
> clk->num_parents = num_parents;
> hw->clk = clk;
>
> - __clk_init(dev, clk);
> + /* allocate local copy in case parent_names is __initdata */
> + clk->parent_names = kzalloc((sizeof(char*) * num_parents),
> + GFP_KERNEL);
> +
> + if (!clk->parent_names) {
> + pr_err("%s: could not allocate clk->parent_names\n", __func__);
> + goto fail_parent_names;
> + }
> +
> + /* copy each string name in case parent_names is __initdata */
... to here.
The rationale is that when this code is changed later someone might use
ret above and doesn't remember that the code below expects ret to be
initialized with -ENOMEM. Also it's easier to see that the code is
correct.
Sascha
> + for (i = 0; i < num_parents; i++) {
> + clk->parent_names[i] = kstrdup(parent_names[i], GFP_KERNEL);
> + if (!clk->parent_names[i]) {
> + pr_err("%s: could not copy parent_names\n", __func__);
> + goto fail_parent_names_copy;
> + }
> + }
> +
> + ret = __clk_init(dev, clk);
> + if (!ret)
> + return clk;
>
> - return clk;
> +fail_parent_names_copy:
> + while (--i >= 0)
> + kfree(clk->parent_names[i]);
> + kfree(clk->parent_names);
> +fail_parent_names:
> + kfree(clk);
> +fail_out:
> + return ERR_PTR(ret);
> }
> EXPORT_SYMBOL_GPL(clk_register);
>
> diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
> index e9c8b98..e7032fd 100644
> --- a/include/linux/clk-private.h
> +++ b/include/linux/clk-private.h
> @@ -181,8 +181,10 @@ struct clk {
> *
> * It is not necessary to call clk_register if __clk_init is used directly with
> * statically initialized clock data.
> + *
> + * Returns 0 on success, otherwise an error code.
> */
> -void __clk_init(struct device *dev, struct clk *clk);
> +int __clk_init(struct device *dev, struct clk *clk);
>
> #endif /* CONFIG_COMMON_CLK */
> #endif /* CLK_PRIVATE_H */
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 8981435..97f9fab 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -274,7 +274,8 @@ struct clk *clk_register_mux(struct device *dev, const char *name,
> * clk_register is the primary interface for populating the clock tree with new
> * clock nodes. It returns a pointer to the newly allocated struct clk which
> * cannot be dereferenced by driver code but may be used in conjuction with the
> - * rest of the clock API.
> + * rest of the clock API. In the event of an error clk_register will return an
> + * error code; drivers must test for an error code after calling clk_register.
> */
> struct clk *clk_register(struct device *dev, const char *name,
> const struct clk_ops *ops, struct clk_hw *hw,
> --
> 1.7.5.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
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