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SubjectRe: [PATCH 1/3] tools: memory-model: Prepare for data-race detection
On Mon, Apr 22, 2019 at 12:17:45PM -0400, Alan Stern wrote:
> This patch makes some slight alterations to linux-kernel.cat in
> preparation for adding support for data-race detection to the
> Linux-Kernel Memory Model.
>
> The definitions of relations involved in Acquire, Release, and
> unlock-lock ordering are moved up earlier in the source file.
>
> The rmb relation is factored through the new R4rmb class: the
> class of reads to which rmb will apply.
>
> The definition of the fence relation is moved earlier, and it
> is split up into read- and write-fences (rmb and wmb) and all
> the others.
>
> This should not make any functional changes.
>
> Signed-off-by: Alan Stern <stern@rowland.harvard.edu>

Thank you, Alan, I have queued all three onto -rcu for review and testing.
FYI, I rebased my smp_mb__{before,after}_atomic() patch on top of yours
to avoid the conflict.

Which demonstrates non-commutativity of patches. Your patches conflict
with mine, but mine does not conflict with yours. ;-)

Thanx, Paul

> ---
>
>
> tools/memory-model/linux-kernel.cat | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> Index: usb-devel/tools/memory-model/linux-kernel.cat
> ===================================================================
> --- usb-devel.orig/tools/memory-model/linux-kernel.cat
> +++ usb-devel/tools/memory-model/linux-kernel.cat
> @@ -26,8 +26,14 @@ include "lock.cat"
> (* Basic relations *)
> (*******************)
>
> +(* Release Acquire *)
> +let acq-po = [Acquire] ; po ; [M]
> +let po-rel = [M] ; po ; [Release]
> +let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po
> +
> (* Fences *)
> -let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn]
> +let R4rmb = R \ Noreturn (* Reads for which rmb works *)
> +let rmb = [R4rmb] ; fencerel(Rmb) ; [R4rmb]
> let wmb = [W] ; fencerel(Wmb) ; [W]
> let mb = ([M] ; fencerel(Mb) ; [M]) |
> ([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) |
> @@ -36,13 +42,10 @@ let mb = ([M] ; fencerel(Mb) ; [M]) |
> ([M] ; po ; [UL] ; (co | po) ; [LKW] ;
> fencerel(After-unlock-lock) ; [M])
> let gp = po ; [Sync-rcu | Sync-srcu] ; po?
> -
> let strong-fence = mb | gp
>
> -(* Release Acquire *)
> -let acq-po = [Acquire] ; po ; [M]
> -let po-rel = [M] ; po ; [Release]
> -let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po
> +let nonrw-fence = strong-fence | po-rel | acq-po
> +let fence = nonrw-fence | wmb | rmb
>
> (**********************************)
> (* Fundamental coherence ordering *)
> @@ -65,7 +68,6 @@ let rwdep = (dep | ctrl) ; [W]
> let overwrite = co | fr
> let to-w = rwdep | (overwrite & int)
> let to-r = addr | (dep ; rfi)
> -let fence = strong-fence | wmb | po-rel | rmb | acq-po
> let ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int)
>
> (* Propagation: Ordering from release operations and strong fences. *)
>
>

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