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SubjectRe: [PATCH v5 2/5] firmware: encapsulate firmware loading status
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Hi Luis,


On 09/09/2016 02:12 PM, Daniel Wagner wrote:
> The firmware user helper code tracks the current state of the loading
> process via unsigned long status and a complection in struct
> firmware_buf. We only need this for the usermode helper as such we can
> encapsulate all this data into its own data structure.

I don't think we are able to move the completion code into a
CONFIG_FW_LOADER_HELPER section. The direct loading path uses completion
as well.

> +#ifdef CONFIG_FW_LOADER_USER_HELPER
> +
> +enum {
> + FW_UMH_UNKNOWN,
> + FW_UMH_LOADING,
> + FW_UMH_DONE,
> + FW_UMH_ABORTED,
> +};

The direct loading path just uses two states, LOADING and DONE. ABORTED
is not used.

> +struct fw_umh {
> + struct completion completion;
> + unsigned long status;
> +};
> +
> +static void fw_umh_init(struct fw_umh *fw_umh)
> +{
> + init_completion(&fw_umh->completion);
> + fw_umh->status = FW_UMH_UNKNOWN;
> +}
> +
> +static int __fw_umh_check(struct fw_umh *fw_umh, unsigned long status)
> +{
> + return test_bit(status, &fw_umh->status);
> +}
> +
> +static int fw_umh_wait_timeout(struct fw_umh *fw_umh, long timeout)
> +{
> + int ret;
> +
> + ret = wait_for_completion_interruptible_timeout(&fw_umh->completion,
> + timeout);
> + if (ret != 0 && test_bit(FW_UMH_ABORTED, &fw_umh->status))
> + return -ENOENT;
> +
> + return ret;
> +}
> +
> +static void __fw_umh_set(struct fw_umh *fw_umh,
> + unsigned long status)
> +{
> + set_bit(status, &fw_umh->status);
> +
> + if (status == FW_UMH_DONE || status == FW_UMH_ABORTED) {
> + clear_bit(FW_UMH_LOADING, &fw_umh->status);
> + complete_all(&fw_umh->completion);
> + }
> +}
> +
> +#define fw_umh_start(fw_umh) \
> + __fw_umh_set(fw_umh, FW_UMH_LOADING)
> +#define fw_umh_done(fw_umh) \
> + __fw_umh_set(fw_umh, FW_UMH_DONE)
> +#define fw_umh_aborted(fw_umh) \
> + __fw_umh_set(fw_umh, FW_UMH_ABORTED)
> +#define fw_umh_is_loading(fw_umh) \
> + __fw_umh_check(fw_umh, FW_UMH_LOADING)
> +#define fw_umh_is_done(fw_umh) \
> + __fw_umh_check(fw_umh, FW_UMH_DONE)
> +#define fw_umh_is_aborted(fw_umh) \
> + __fw_umh_check(fw_umh, FW_UMH_ABORTED)
> +
> +#else /* CONFIG_FW_LOADER_USER_HELPER */
> +
> +#define fw_umh_wait_timeout(fw_st, long) 0
> +
> +#define fw_umh_done(fw_st)
> +#define fw_umh_is_done(fw_st) true
> +#define fw_umh_is_aborted(fw_st) false

We still need the implementation for fw_umh_wait_timeout() and
fw_umh_start(), fw_umh_done() etc. fw_umh_is_aborted() is not needed.


> @@ -309,8 +373,7 @@ static void fw_finish_direct_load(struct device *device,
> struct firmware_buf *buf)
> {
> mutex_lock(&fw_lock);
> - set_bit(FW_STATUS_DONE, &buf->status);
> - complete_all(&buf->completion);
> + fw_umh_done(&buf->fw_umh);
> mutex_unlock(&fw_lock);
> }

Here we signal that we have loaded the firmware

> /* wait until the shared firmware_buf becomes ready (or error) */
> static int sync_cached_firmware_buf(struct firmware_buf *buf)
> {
> int ret = 0;
>
> mutex_lock(&fw_lock);
> - while (!test_bit(FW_STATUS_DONE, &buf->status)) {
> - if (is_fw_load_aborted(buf)) {
> + while (!fw_umh_is_done(&buf->fw_umh)) {
> + if (fw_umh_is_aborted(&buf->fw_umh)) {
> ret = -ENOENT;
> break;
> }
> mutex_unlock(&fw_lock);
> - ret = wait_for_completion_interruptible(&buf->completion);
> + ret = fw_umh_wait_timeout(&buf->fw_umh, 0);
> mutex_lock(&fw_lock);
> }

and here we here we wait for it.

So I suggest to rename it back to fw_status_ and don't move it inside a
CONFIG_FW_LOADER_HELPER section. Drop the special handling of the
ABORTED and add instead a comment that the ABORTED state is not used for
direct loading. This special handling makes unnecessary more complex.
This is a slowpath and this micro optimization is helping to maintain
the code.

cheers,
daniel

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