Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Fri, Mar 03, 2017 at 03:49:38PM +0100, Peter Zijlstra wrote: > On Fri, Mar 03, 2017 at 09:26:50AM +0100, Christian Borntraeger wrote: > > Right. The main purpose is to read/write _ONCE_. You can assume a somewhat > > atomic access for sizes <= word size. And there are certainly places that > >

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Fri, Mar 03, 2017 at 03:49:38PM +0100, Peter Zijlstra wrote: > On Fri, Mar 03, 2017 at 09:26:50AM +0100, Christian Borntraeger wrote: > > Right. The main purpose is to read/write _ONCE_. You can assume a somewhat > > atomic access for sizes <= word size. And there are certainly places that > >

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Fri, Mar 03, 2017 at 09:26:50AM +0100, Christian Borntraeger wrote: > Right. The main purpose is to read/write _ONCE_. You can assume a somewhat > atomic access for sizes <= word size. And there are certainly places that > rely on that. But the *ONCE thing is mostly used for things where we

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Fri, Mar 03, 2017 at 09:26:50AM +0100, Christian Borntraeger wrote: > Right. The main purpose is to read/write _ONCE_. You can assume a somewhat > atomic access for sizes <= word size. And there are certainly places that > rely on that. But the *ONCE thing is mostly used for things where we

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Fri, Mar 3, 2017 at 9:26 AM, Christian Borntraeger wrote: > On 03/02/2017 10:45 PM, Arnd Bergmann wrote: >> Ok, got it. So I guess the behavior of forcing aligned accesses on aligned >> data is accidental, and allowing non-power-of-two arguments is also not >> the main

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Fri, Mar 3, 2017 at 9:26 AM, Christian Borntraeger wrote: > On 03/02/2017 10:45 PM, Arnd Bergmann wrote: >> Ok, got it. So I guess the behavior of forcing aligned accesses on aligned >> data is accidental, and allowing non-power-of-two arguments is also not >> the main purpose. > > > Right.

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On 03/02/2017 10:45 PM, Arnd Bergmann wrote: > On Thu, Mar 2, 2017 at 8:00 PM, Christian Borntraeger > wrote: >> On 03/02/2017 06:55 PM, Arnd Bergmann wrote: >>> On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger >>> wrote: On 03/02/2017

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On 03/02/2017 10:45 PM, Arnd Bergmann wrote: > On Thu, Mar 2, 2017 at 8:00 PM, Christian Borntraeger > wrote: >> On 03/02/2017 06:55 PM, Arnd Bergmann wrote: >>> On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger >>> wrote: On 03/02/2017 05:38 PM, Arnd Bergmann wrote: > > This

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On 03/02/2017 06:55 PM, Arnd Bergmann wrote: > On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger > wrote: >> On 03/02/2017 05:38 PM, Arnd Bergmann wrote: >>> >>> This attempts a rewrite of the two macros, using a simpler implementation >>> for the most common case of

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On 03/02/2017 06:55 PM, Arnd Bergmann wrote: > On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger > wrote: >> On 03/02/2017 05:38 PM, Arnd Bergmann wrote: >>> >>> This attempts a rewrite of the two macros, using a simpler implementation >>> for the most common case of having a naturally

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Thu, Mar 2, 2017 at 8:00 PM, Christian Borntraeger wrote: > On 03/02/2017 06:55 PM, Arnd Bergmann wrote: >> On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger >> wrote: >>> On 03/02/2017 05:38 PM, Arnd Bergmann wrote: This attempts

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Thu, Mar 2, 2017 at 8:00 PM, Christian Borntraeger wrote: > On 03/02/2017 06:55 PM, Arnd Bergmann wrote: >> On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger >> wrote: >>> On 03/02/2017 05:38 PM, Arnd Bergmann wrote: This attempts a rewrite of the two macros, using a simpler

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger wrote: > On 03/02/2017 05:38 PM, Arnd Bergmann wrote: >> >> This attempts a rewrite of the two macros, using a simpler implementation >> for the most common case of having a naturally aligned 1, 2, 4, or (on >> 64-bit

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On Thu, Mar 2, 2017 at 5:51 PM, Christian Borntraeger wrote: > On 03/02/2017 05:38 PM, Arnd Bergmann wrote: >> >> This attempts a rewrite of the two macros, using a simpler implementation >> for the most common case of having a naturally aligned 1, 2, 4, or (on >> 64-bit architectures) 8 byte

[PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

When CONFIG_KASAN is enabled, the READ_ONCE/WRITE_ONCE macros cause rather large kernel stacks, e.g.: mm/vmscan.c: In function 'shrink_page_list': mm/vmscan.c:1333:1: error: the frame size of 3456 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] block/cfq-iosched.c: In function

[PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

When CONFIG_KASAN is enabled, the READ_ONCE/WRITE_ONCE macros cause rather large kernel stacks, e.g.: mm/vmscan.c: In function 'shrink_page_list': mm/vmscan.c:1333:1: error: the frame size of 3456 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] block/cfq-iosched.c: In function

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On 03/02/2017 05:38 PM, Arnd Bergmann wrote: > When CONFIG_KASAN is enabled, the READ_ONCE/WRITE_ONCE macros cause > rather large kernel stacks, e.g.: > > mm/vmscan.c: In function 'shrink_page_list': > mm/vmscan.c:1333:1: error: the frame size of 3456 bytes is larger than 3072 > bytes

Re: [PATCH 02/26] rewrite READ_ONCE/WRITE_ONCE

On 03/02/2017 05:38 PM, Arnd Bergmann wrote: > When CONFIG_KASAN is enabled, the READ_ONCE/WRITE_ONCE macros cause > rather large kernel stacks, e.g.: > > mm/vmscan.c: In function 'shrink_page_list': > mm/vmscan.c:1333:1: error: the frame size of 3456 bytes is larger than 3072 > bytes