linux-kernel - Re: [PATCH v4 3/4] firmware: Drop bit ops in favor of simple state machine

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Date:   Thu, 8 Sep 2016 03:45:55 +0200
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Daniel Wagner <wagi@...om.org>
Cc:     linux-kernel@...r.kernel.org,
        Daniel Wagner <daniel.wagner@...-carit.de>,
        Ming Lei <ming.lei@...onical.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v4 3/4] firmware: Drop bit ops in favor of simple state
 machine

On Wed, Sep 07, 2016 at 10:45:07AM +0200, Daniel Wagner wrote:
> From: Daniel Wagner <daniel.wagner@...-carit.de>
> 
> We track the state of the loading with bit ops. Since the state machine
> has only a couple of states and there are only a few simple state
> transition 

And they are all mutually exclusive ?

> we can model this simplify.
> 
> 	   UNKNOWN -> LOADING -> DONE | ABORTED

So why unsigned long ? Why not a u8?

> 
> Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
> Cc: Ming Lei <ming.lei@...onical.com>
> Cc: Luis R. Rodriguez <mcgrof@...nel.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  drivers/base/firmware_class.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index b11fbb0..7757c03 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -120,16 +120,18 @@ static void fw_status_init(struct fw_status *fw_st)
>  
>  static int __fw_status_check(struct fw_status *fw_st, unsigned long status)
>  {
> -	return test_bit(status, &fw_st->status);
> +	return fw_st->status == status;
>  }
>  
>  static int fw_status_wait_timeout(struct fw_status *fw_st, long timeout)
>  {
> +	unsigned long status;
>  	int ret;
>  
>  	ret = wait_for_completion_interruptible_timeout(&fw_st->completion,
>  							timeout);
> -	if (ret == 0 && test_bit(FW_STATUS_ABORTED, &fw_st->status))
> +	status = READ_ONCE(fw_st->status);
> +	if (ret == 0 && status == FW_STATUS_ABORTED)
>  		return -ENOENT;
>  
>  	return ret;
> @@ -138,13 +140,11 @@ static int fw_status_wait_timeout(struct fw_status *fw_st, long timeout)
>  static void __fw_status_set(struct fw_status *fw_st,
>  			  unsigned long status)
>  {
> -	set_bit(status, &fw_st->status);
> +	WRITE_ONCE(fw_st->status, status);
>  
>  	if (status == FW_STATUS_DONE ||
> -			status == FW_STATUS_ABORTED) {
> -		clear_bit(FW_STATUS_LOADING, &fw_st->status);
> +			status == FW_STATUS_ABORTED)
>  		complete_all(&fw_st->completion);
> -	}
>  }
>  
>  #define fw_status_start(fw_st)					\

See if all the above were prefixed with fw_umh or something like it
it would make this easier to read and tell this is all umh related.

  Luis