Re: [PATCH] drivers/usb: use READ_ONCE instead of deprecated ACCESS_ONCE

From	Davidlohr Bueso <dave@stgolabs.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH] drivers/usb: use READ_ONCE instead of deprecated ACCESS_ONCE
Date	2016-11-20 17:20 +0100
Message-ID	<sFD0t-5RA-7@gated-at.bofh.it> (permalink)
References	<sFjXP-OR-3@gated-at.bofh.it> <sFwLn-Jd-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi Greg!

On Sun, 20 Nov 2016, Greg KH wrote:

>On Sat, Nov 19, 2016 at 11:54:25AM -0800, Davidlohr Bueso wrote:
>> With the new standardized functions, we can replace all ACCESS_ONCE()
>> calls across relevant drivers/usb/.
>>
>> ACCESS_ONCE() does not work reliably on non-scalar types. For example
>> gcc 4.6 and 4.7 might remove the volatile tag for such accesses during
>> the SRA (scalar replacement of aggregates) step:
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
>>
>> Update the new calls regardless of if it is a scalar type, this is
>> cleaner than having three alternatives.
>>
>> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
>
>Nit, this doesn't match your From: line :(

That's on purpose, and all my patches are the same.

>If this is the case, why not just replacing the define for ACCESS_ONCE()
>with READ_ONCE() and then go back and just do a search/replace for the
>whole kernel all at once?

So that we don't have three variants; the idea is to eventually
get rid of ACCESS_ONCE entirely.

>
>Or just send Linus a patch for this all at once after -rc1 is out?

No rush, whenever you see fit.

Thanks,
Davidlohr

Thread

[PATCH] drivers/usb: use READ_ONCE instead of deprecated ACCESS_ONCE Davidlohr Bueso <dave@stgolabs.net> - 2016-11-19 21:00 +0100
  Re: [PATCH] drivers/usb: use READ_ONCE instead of deprecated  ACCESS_ONCE Greg KH <gregkh@linuxfoundation.org> - 2016-11-20 10:40 +0100
    Re: [PATCH] drivers/usb: use READ_ONCE instead of deprecated  ACCESS_ONCE Mark Rutland <mark.rutland@arm.com> - 2016-11-20 13:20 +0100
    Re: [PATCH] drivers/usb: use READ_ONCE instead of deprecated  ACCESS_ONCE Davidlohr Bueso <dave@stgolabs.net> - 2016-11-20 17:20 +0100
      Re: [PATCH] drivers/usb: use READ_ONCE instead of deprecated  ACCESS_ONCE Greg KH <gregkh@linuxfoundation.org> - 2016-11-21 08:20 +0100

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