From: Michael Ellerman <patch-notifications@ellerman•id.au>
To: Frederic Barrat <fbarrat@linux•vnet.ibm.com>,
linuxppc-dev@lists•ozlabs.org, benh@kernel•crashing.org,
andrew.donnellan@au1•ibm.com, clombard@linux•vnet.ibm.com,
vaibhav@linux•vnet.ibm.com
Cc: alistair@popple•id.au
Subject: Re: [v2,2/3] cxl: Fix driver use count
Date: Thu, 31 Aug 2017 21:36:32 +1000 (AEST) [thread overview]
Message-ID: <3xjgLm4Sn9z9t45@ozlabs.org> (raw)
In-Reply-To: <20170830101550.16821-2-fbarrat@linux.vnet.ibm.com>
On Wed, 2017-08-30 at 10:15:49 UTC, Frederic Barrat wrote:
> cxl keeps a driver use count, which is used with the hash memory model
> on p8 to know when to upgrade local TLBIs to global and to trigger
> callbacks to manage the MMU for PSL8.
>
> If a process opens a context and closes without attaching or fails the
> attachment, the driver use count is never decremented. As a
> consequence, TLB invalidations remain global, even if there are no
> active cxl contexts.
>
> We should increment the driver use count when the process is attaching
> to the cxl adapter, and not on open. It's not needed before the
> adapter starts using the context and the use count is decremented on
> the detach path, so it makes more sense.
>
> It affects only the user api. The kernel api is already doing The
> Right Thing.
>
> Signed-off-by: Frederic Barrat <fbarrat@linux•vnet.ibm.com>
> Cc: stable@vger•kernel.org # v4.2+
> Fixes: 7bb5d91a4dda ("cxl: Rework context lifetimes")
> Acked-by: Andrew Donnellan <andrew.donnellan@au1•ibm.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/197267d0356004a31c4d6b6336598f
cheers
next prev parent reply other threads:[~2017-08-31 11:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-30 10:15 [PATCH v2 1/3] powerpc/mm: Export flush_all_mm() Frederic Barrat
2017-08-30 10:15 ` [PATCH v2 2/3] cxl: Fix driver use count Frederic Barrat
2017-08-30 13:18 ` Michael Ellerman
2017-08-31 11:36 ` Michael Ellerman [this message]
2017-08-30 10:15 ` [PATCH v2 3/3] cxl: Enable global TLBIs for cxl contexts Frederic Barrat
2017-08-30 13:17 ` [PATCH v2 1/3] powerpc/mm: Export flush_all_mm() Michael Ellerman
2017-08-30 13:59 ` Frederic Barrat
2017-08-30 21:01 ` Benjamin Herrenschmidt
2017-08-31 9:13 ` Frederic Barrat
2017-08-30 21:00 ` Benjamin Herrenschmidt
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