linux-kernel - Re: [PATCH 4/6] usb-serial: optimize sysrq function calls

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Date:	Wed, 10 Mar 2010 16:18:42 -0600
From:	Jason Wessel <jason.wessel@...driver.com>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	gregkh@...e.de, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Alan Cox <alan@...ux.intel.com>,
	Oliver Neukum <oliver@...kum.org>
Subject: Re: [PATCH 4/6] usb-serial: optimize sysrq function calls

Alan Stern wrote:
> On Tue, 9 Mar 2010, Jason Wessel wrote:
>
>   
>> There is no need to have external function calls for the sysrq
>> functions.  The compiler can inline the sysrq calls such that they are
>> entirely a NOP if CONFIG_MAGIC_SYSRQ is not set.
>>     
>
> This is not the best way to do what you want.  Keep 
> usb_serial_handle_sysrq_char() and usb_serial_handle_break() as 
> out-of-line routines in generic.c, but make them conditional on 
> CONFIG_MAGIC_SYSRQ.  Then in the header file, depending on whether or 
> not CONFIG_MAGIC_SYSRQ is defined, either put the usual extern function 
> declarations or else put do-nothing inline definitions.
>
> The advantage of keeping the functions out-of-line is the reduced
> amount of code space (since the bodies aren't replicated every place
> they get used).  This way you keep that advantage while still getting
> the NOP implementation if CONFIG_MAGIC_SYSRQ isn't set.
>   

It is probably fine to just drop this patch entirely then.

I had originally made the change to keep it similar to the uart based
serial drivers where the definitions are inlined.

Jason.
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