Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Tue, Aug 23, 2016 at 07:23:26AM -0700, Paul E. McKenney wrote: > On Tue, Aug 23, 2016 at 03:45:51PM +0200, Geert Uytterhoeven wrote: > > Hi Paul, > > > > On Tue, Aug 23, 2016 at 3:43 PM, Paul E. McKenney > > wrote: > > > On Tue, Aug 23, 2016 at 08:39:18AM +0200, Geert Uytterhoeven wrote: > > >

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, Aug 22, 2016 at 08:14:43AM -0700, Paul E. McKenney wrote: > The __call_rcu() assertion that checks only the bottom bit of the > rcu_head pointer is a bit counter-intuitive in these days of ubiquitous > 64-bit systems. This commit therefore records the reason for this > odd alignment check,

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, Aug 22, 2016 at 06:25:53PM +0200, Peter Zijlstra wrote: > On Mon, Aug 22, 2016 at 08:14:43AM -0700, Paul E. McKenney wrote: > > The __call_rcu() assertion that checks only the bottom bit of the > > rcu_head pointer is a bit counter-intuitive in these days of ubiquitous > > 64-bit systems.

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, Aug 22, 2016 at 10:34 AM, Paul E. McKenney wrote: > That does have much to say for itself, though I would prefer sizeof(void > *) to sizeof(unsigned long). But would it make sense to define a mask > on a per-architecture basis, with the default being (sizeof(void *) - 1)? > Then maybe an

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, Aug 22, 2016 at 11:48:53AM -0700, Eric Dumazet wrote: > On Mon, Aug 22, 2016 at 10:34 AM, Paul E. McKenney > wrote: > > > That does have much to say for itself, though I would prefer sizeof(void > > *) to sizeof(unsigned long). But would it make sense to define a mask > > on a per-archit

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, 22 Aug 2016 20:56:09 +0200 Peter Zijlstra wrote: > > Don't we have __alignof__(void *) to avoid #ifdef CONFIG_M68K and > > other new macros ? > > Yes, but that 'hides' the m68k funny, while doing an explicit #ifdef has > documentation value... but I don't care too deeply. I'd recommen

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, Aug 22, 2016 at 03:18:54PM -0400, Steven Rostedt wrote: > On Mon, 22 Aug 2016 20:56:09 +0200 > Peter Zijlstra wrote: > > > > Don't we have __alignof__(void *) to avoid #ifdef CONFIG_M68K and > > > other new macros ? Hmmm... Does __alignof__(void *) give two-byte alignment on m68k, all

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

Hi Paul, On Mon, Aug 22, 2016 at 9:54 PM, Paul E. McKenney wrote: > On Mon, Aug 22, 2016 at 03:18:54PM -0400, Steven Rostedt wrote: >> On Mon, 22 Aug 2016 20:56:09 +0200 >> Peter Zijlstra wrote: >> >> > > Don't we have __alignof__(void *) to avoid #ifdef CONFIG_M68K and >> > > other new macros ?

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Mon, Aug 22, 2016 at 10:48:57PM +0200, Geert Uytterhoeven wrote: > Hi Paul, > > On Mon, Aug 22, 2016 at 9:54 PM, Paul E. McKenney > wrote: > > On Mon, Aug 22, 2016 at 03:18:54PM -0400, Steven Rostedt wrote: > >> On Mon, 22 Aug 2016 20:56:09 +0200 > >> Peter Zijlstra wrote: > >> > >> > > Don't

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

Hi Paul, On Mon, Aug 22, 2016 at 11:16 PM, Paul E. McKenney wrote: > On Mon, Aug 22, 2016 at 10:48:57PM +0200, Geert Uytterhoeven wrote: >> On Mon, Aug 22, 2016 at 9:54 PM, Paul E. McKenney >> wrote: >> > On Mon, Aug 22, 2016 at 03:18:54PM -0400, Steven Rostedt wrote: >> >> On Mon, 22 Aug 2016 2

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Tue, Aug 23, 2016 at 08:39:18AM +0200, Geert Uytterhoeven wrote: > Hi Paul, > > On Mon, Aug 22, 2016 at 11:16 PM, Paul E. McKenney > wrote: > > On Mon, Aug 22, 2016 at 10:48:57PM +0200, Geert Uytterhoeven wrote: > >> On Mon, Aug 22, 2016 at 9:54 PM, Paul E. McKenney > >> wrote: > >> > On Mon,

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

Hi Paul, On Tue, Aug 23, 2016 at 3:43 PM, Paul E. McKenney wrote: > On Tue, Aug 23, 2016 at 08:39:18AM +0200, Geert Uytterhoeven wrote: >> On Mon, Aug 22, 2016 at 11:16 PM, Paul E. McKenney >> wrote: >> > On Mon, Aug 22, 2016 at 10:48:57PM +0200, Geert Uytterhoeven wrote: >> >> On Mon, Aug 22, 2

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Tue, Aug 23, 2016 at 4:23 PM, Paul E. McKenney wrote: > commit 89d39c83d193733ed5fff1c480cd42c9de1da404 > Author: Paul E. McKenney > Date: Tue Aug 23 06:51:47 2016 -0700 > > rcu: Tighted up __call_rcu() rcu_head alignment check > > Commit 720abae3d68ae ("rcu: force alignment on struc

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Tue, Aug 23, 2016 at 03:45:51PM +0200, Geert Uytterhoeven wrote: > Hi Paul, > > On Tue, Aug 23, 2016 at 3:43 PM, Paul E. McKenney > wrote: > > On Tue, Aug 23, 2016 at 08:39:18AM +0200, Geert Uytterhoeven wrote: > >> On Mon, Aug 22, 2016 at 11:16 PM, Paul E. McKenney > >> wrote: > >> > On Mon,

Re: [PATCH tip/core/rcu 2/2] documentation: Record reason for rcu_head two-byte alignment

On Tue, Aug 23, 2016 at 04:30:47PM +0200, Geert Uytterhoeven wrote: > On Tue, Aug 23, 2016 at 4:23 PM, Paul E. McKenney > wrote: > > commit 89d39c83d193733ed5fff1c480cd42c9de1da404 > > Author: Paul E. McKenney > > Date: Tue Aug 23 06:51:47 2016 -0700 > > > > rcu: Tighted up __call_rcu() rcu