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(p200300f6ef1b2000944ccbc71e1c2c47.dip0.t-ipconnect.de. [2003:f6:ef1b:2000:944c:cbc7:1e1c:2c47]) by smtp.gmail.com with ESMTPSA id h2-20020a1709063c0200b00a3d1ea6134dsm1155253ejg.197.2024.02.14.04.48.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Feb 2024 04:48:10 -0800 (PST) Message-ID: <71fa22870246c4ed6ae9cbb2cb93db557dd855f7.camel@gmail.com> Subject: Re: [PATCH v2 2/2] of: dynamic: flush devlinks workqueue before destroying the changeset From: Nuno =?ISO-8859-1?Q?S=E1?= To: Saravana Kannan Cc: Rob Herring , Nuno Sa , Greg Kroah-Hartman , "Rafael J. Wysocki" , Frank Rowand , Andy Shevchenko , Daniel Scally , Heikki Krogerus , Sakari Ailus , Len Brown , linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Android Kernel Team Date: Wed, 14 Feb 2024 13:51:29 +0100 In-Reply-To: References: <20240205-fix-device-links-overlays-v2-0-5344f8c79d57@analog.com> <20240205-fix-device-links-overlays-v2-2-5344f8c79d57@analog.com> <20240213145131.GA1180152-robh@kernel.org> <48a86fa6908a2a7a38a45dc6dbb5574c4a9d7400.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2024-02-13 at 19:44 -0800, Saravana Kannan wrote: > On Tue, Feb 13, 2024 at 6:57=E2=80=AFAM Nuno S=C3=A1 wrote: > >=20 > > On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote: > > > On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno S=C3=A1 wrote: > > > > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote: > > > > > Device links will drop their supplier + consumer refcounts > > > > > asynchronously. That means that the refcount of the of_node attac= hed > > > > > to > > > > > these devices will also be dropped asynchronously and so we canno= t > > > > > guarantee the DT overlay assumption that the of_node refcount mus= t be > > > > > 1 in > > > > > __of_changeset_entry_destroy(). > > > > >=20 > > > > > Given the above, call the new fwnode_links_flush_queue() helper t= o > > > > > flush > > > > > the devlink workqueue so we can be sure that all links are droppe= d > > > > > before > > > > > doing the proper checks. > > > > >=20 > > > > > Signed-off-by: Nuno Sa > > > > > --- > > > > > =C2=A0drivers/of/dynamic.c | 8 ++++++++ > > > > > =C2=A01 file changed, 8 insertions(+) > > > > >=20 > > > > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c > > > > > index 3bf27052832f..b7153c72c9c9 100644 > > > > > --- a/drivers/of/dynamic.c > > > > > +++ b/drivers/of/dynamic.c > > > > > @@ -14,6 +14,7 @@ > > > > > =C2=A0#include > > > > > =C2=A0#include > > > > > =C2=A0#include > > > > > +#include > > > > >=20 > > > > > =C2=A0#include "of_private.h" > > > > >=20 > > > > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node); > > > > >=20 > > > > > =C2=A0static void __of_changeset_entry_destroy(struct of_changese= t_entry > > > > > *ce) > > > > > =C2=A0{ > > > > > + /* > > > > > +=C2=A0 * device links drop their device references (and hence th= eir > > > > > of_node > > > > > +=C2=A0 * references) asynchronously on a dedicated workqueue. He= nce we > > > > > need > > > > > +=C2=A0 * to flush it to make sure everything is done before doin= g the > > > > > below > > > > > +=C2=A0 * checks. > > > > > +=C2=A0 */ > > > > > + fwnode_links_flush_queue(); > > > > > =C2=A0 if (ce->action =3D=3D OF_RECONFIG_ATTACH_NODE && > > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 of_node_check_flag(ce->np, OF_OVER= LAY)) { > > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (kref_r= ead(&ce->np->kobj.kref) > 1) { > > > > >=20 > > > >=20 > > > > Hi Rob and Frank, > > > >=20 > > > > Any way you could take a look at this and see if you're ok with the > > > > change > > > > in the > > > > overlay code? > > > >=20 > > > > On the devlink side , we already got the ok from Rafael. > > >=20 > > > Didn't Saravana say he was going to look at this? As of yesterday, he= 's > > > also a DT maintainer so deferring to him. > > >=20 > >=20 > > Yeah, I did asked him but I guess he never had the time for it... Sarav= ana, > > could you please give some feedback on this? I think the most sensible = part > > is > > on the devlink side but I assume this is not going to be merged without= an > > ack > > from a DT maintainer... >=20 > Sorry for the delay Nuno. I'll get to this. I promise. This week is a bit > busy. >=20 No worries. Just making sure it's not forgotten :) - Nuno S=C3=A1