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SubjectRe: [RFC PATCH 01/13] driver core: firmware loader: simplify pages ownership transfer
On Wed, Jul 25, 2012 at 01:00:01AM +0800, Ming Lei wrote:
> This patch doesn't transfer ownership of pages' buffer to the
> instance of firmware until the firmware loading is completed,
> which will simplify firmware_loading_store a lot, so help
> to introduce the following cache_firmware and uncache_firmware
> mechanism during system suspend-resume cycle.
>
> In fact, this patch fixes one bug: if writing data into
> firmware loader device is bypassed between writting 1 and 0 to
> 'loading', OOPS will be triggered without the patch.
>
> Also add some comments to make code more readable.
>
> Signed-off-by: Ming Lei <ming.lei@canonical.com>
> ---
> drivers/base/firmware_class.c | 57 ++++++++++++++++++++++++-----------------
> 1 file changed, 34 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 803cfc1..f789bbd 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -93,6 +93,8 @@ struct firmware_priv {
> struct completion completion;
> struct firmware *fw;
> unsigned long status;
> + void *data;
> + size_t size;
> struct page **pages;
> int nr_pages;
> int page_array_size;
> @@ -156,9 +158,11 @@ static void fw_dev_release(struct device *dev)
> struct firmware_priv *fw_priv = to_firmware_priv(dev);
> int i;
>
> + /* free untransfered pages buffer */
> for (i = 0; i < fw_priv->nr_pages; i++)
> __free_page(fw_priv->pages[i]);
> kfree(fw_priv->pages);
> +
> kfree(fw_priv);
>
> module_put(THIS_MODULE);
> @@ -194,6 +198,7 @@ static ssize_t firmware_loading_show(struct device *dev,
> return sprintf(buf, "%d\n", loading);
> }
>
> +/* firmware holds the ownership of pages */
> static void firmware_free_data(const struct firmware *fw)
> {
> int i;
> @@ -237,9 +242,7 @@ static ssize_t firmware_loading_store(struct device *dev,
>
> switch (loading) {
> case 1:
> - firmware_free_data(fw_priv->fw);
> - memset(fw_priv->fw, 0, sizeof(struct firmware));
> - /* If the pages are not owned by 'struct firmware' */
> + /* discarding any previous partial load */
> for (i = 0; i < fw_priv->nr_pages; i++)
> __free_page(fw_priv->pages[i]);
> kfree(fw_priv->pages);
> @@ -250,20 +253,6 @@ static ssize_t firmware_loading_store(struct device *dev,
> break;
> case 0:
> if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) {
> - vunmap(fw_priv->fw->data);
> - fw_priv->fw->data = vmap(fw_priv->pages,
> - fw_priv->nr_pages,
> - 0, PAGE_KERNEL_RO);
> - if (!fw_priv->fw->data) {
> - dev_err(dev, "%s: vmap() failed\n", __func__);
> - goto err;
> - }
> - /* Pages are now owned by 'struct firmware' */
> - fw_priv->fw->pages = fw_priv->pages;
> - fw_priv->pages = NULL;
> -
> - fw_priv->page_array_size = 0;
> - fw_priv->nr_pages = 0;
> complete(&fw_priv->completion);
> clear_bit(FW_STATUS_LOADING, &fw_priv->status);
> break;
> @@ -273,7 +262,6 @@ static ssize_t firmware_loading_store(struct device *dev,
> dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
> /* fallthrough */
> case -1:
> - err:
> fw_load_abort(fw_priv);
> break;
> }
> @@ -299,12 +287,12 @@ static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
> ret_count = -ENODEV;
> goto out;
> }
> - if (offset > fw->size) {
> + if (offset > fw_priv->size) {
> ret_count = 0;
> goto out;
> }
> - if (count > fw->size - offset)
> - count = fw->size - offset;
> + if (count > fw_priv->size - offset)
> + count = fw_priv->size - offset;
>
> ret_count = count;
>
> @@ -396,6 +384,7 @@ static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
> retval = -ENODEV;
> goto out;
> }
> +
> retval = fw_realloc_buffer(fw_priv, offset + count);
> if (retval)
> goto out;
> @@ -418,7 +407,7 @@ static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
> count -= page_cnt;
> }
>
> - fw->size = max_t(size_t, offset, fw->size);
> + fw_priv->size = max_t(size_t, offset, fw_priv->size);
> out:
> mutex_unlock(&fw_lock);
> return retval;
> @@ -504,6 +493,24 @@ static void _request_firmware_cleanup(const struct firmware **firmware_p)
> *firmware_p = NULL;
> }
>
> +/* transfer the ownership of pages to firmware */
> +static void fw_set_page_data(struct firmware_priv *fw_priv)
> +{
> + struct firmware *fw = fw_priv->fw;
> +
> + fw_priv->data = vmap(fw_priv->pages, fw_priv->nr_pages,
> + 0, PAGE_KERNEL_RO);

We don't need to check the return value of vmap() here like we do above?

> + fw->data = fw_priv->data;
> + fw->pages = fw_priv->pages;
> + fw->size = fw_priv->size;

--
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
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GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
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