linux-kernel - Re: [PATCH V2 RESEND] firmware: simplify defining and handling FW_OPT

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Date:   Thu, 23 Feb 2017 14:00:30 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     Ming Lei <ming.lei@...onical.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH V2 RESEND] firmware: simplify defining and handling
 FW_OPT_FALLBACK

On 02/21/2017 06:10 PM, Luis R. Rodriguez wrote:
> On Wed, Feb 15, 2017 at 04:05:13PM +0100, Rafał Miłecki wrote:
>> From: Rafał Miłecki <rafal@...ecki.pl>
>>
>> I found handling of FW_OPT_FALLBACK a bit complex. It was defined using
>> another option and their values were dependent on kernel config.
>>
>> It was also non-trivial to follow the code. Some callers were using
>> FW_OPT_FALLBACK which was confusing since the _request_firmware function
>> was always checking for FW_OPT_USERHELPER (the same bit in a relevant
>> configuration).
>>
>> With this patch FW_OPT_USERHELPER gets its own bit and is explicitly
>> checked in the _request_firmware which hopefully makes code easier to
>> understand.
>>
>> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
>> ---
>> V2: s/config_enabled/IS_ENABLED/ to compile since c0a0aba8e47 ("kconfig.h: remove config_enabled() macro")
>>
>> RESEND: I was suggested to resend this patch (thanks Greg!)
>>
>> Ming/Luis/Greg: could someone accept this patch, please? I hope this trivial
>> cleanup isn't too big deal.
>> ---
>>  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 ac350c518e0c..d05be1732c8b 100644
>> --- a/drivers/base/firmware_class.c
>> +++ b/drivers/base/firmware_class.c
>> @@ -190,13 +190,9 @@ static int __fw_state_check(struct fw_state *fw_st, enum fw_status status)
>>  #else
>>  #define FW_OPT_USERHELPER	0
>>  #endif
>> -#ifdef CONFIG_FW_LOADER_USER_HELPER_FALLBACK
>> -#define FW_OPT_FALLBACK		FW_OPT_USERHELPER
>> -#else
>> -#define FW_OPT_FALLBACK		0
>> -#endif
>>  #define FW_OPT_NO_WARN	(1U << 3)
>>  #define FW_OPT_NOCACHE	(1U << 4)
>> +#define FW_OPT_FALLBACK	(1U << 5)
>>
>>  struct firmware_cache {
>>  	/* firmware_buf instance will be added into the below list */
>> @@ -1210,8 +1206,12 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
>>  			dev_warn(device,
>>  				 "Direct firmware load for %s failed with error %d\n",
>>  				 name, ret);
>> -		if (opt_flags & FW_OPT_USERHELPER) {
>> +		if (IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK) &&
>> +		    opt_flags & FW_OPT_FALLBACK) {
>>  			dev_warn(device, "Falling back to user helper\n");
>> +			opt_flags |= FW_OPT_USERHELPER;
>> +		}
>> +		if (opt_flags & FW_OPT_USERHELPER) {
>>  			ret = fw_load_from_user_helper(fw, name, device,
>>  						       opt_flags, timeout);
>
> I've given this some thought and while at first glance it seems like an
> improvement but it deviates from the traditional way we fold out features in
> Linux. Instead let's just wrap properly the entire functionality into wrappers
> which will no-op for when the fallback mechanism is disabled. That dev_warn()
> for example can just be moved to the call fw_load_from_user_helper() and when
> we disable the feature it will be no-op. Ultimately I'd like to shove the
> entire fallback mechanism to its own file.

I don't understand this part: "dev_warn() for example can just be moved to the
call fw_load_from_user_helper()".

Did you mean moving dev_warn into fw_load_from_user_helper function? Should I
move (opt_flags & FW_OPT_USERHELPER) condition there as well?