Messages in this thread | | | Date | Tue, 26 May 2020 23:53:33 +0200 | From | Michael Walle <> | Subject | Re: [PATCH v2] driver core: Update device link status correctly for SYNC_STATE_ONLY links |
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Am 2020-05-26 23:45, schrieb Saravana Kannan: > On Tue, May 26, 2020 at 2:13 PM Michael Walle <michael@walle.cc> wrote: >> >> Am 2020-05-26 21:43, schrieb Saravana Kannan: >> > When SYNC_STATE_ONLY support was added in commit 05ef983e0d65 ("driver >> > core: Add device link support for SYNC_STATE_ONLY flag"), >> > SYNC_STATE_ONLY links were treated similar to STATELESS links in terms >> > of not blocking consumer probe if the supplier hasn't probed yet. >> > >> > That caused a SYNC_STATE_ONLY device link's status to not get updated. >> > Since SYNC_STATE_ONLY device link is no longer useful once the >> > consumer probes, commit 21c27f06587d ("driver core: Fix >> > SYNC_STATE_ONLY device link implementation") addresses the status >> > update issue by deleting the SYNC_STATE_ONLY device link instead of >> > complicating the status update code. >> > >> > However, there are still some cases where we need to update the status >> > of a SYNC_STATE_ONLY device link. This is because a SYNC_STATE_ONLY >> > device link can later get converted into a normal MANAGED device link >> > when a normal MANAGED device link is created between a supplier and >> > consumer that already have a SYNC_STATE_ONLY device link between them. >> > >> > If a SYNC_STATE_ONLY device link's status isn't maintained correctly >> > till it's converted to a normal MANAGED device link, then the normal >> > MANAGED device link will end up with a wrong link status. This can >> > cause >> > a warning stack trace[1] when the consumer device probes successfully. >> > >> > This commit fixes the SYNC_STATE_ONLY device link status update issue >> > where it wouldn't transition correctly from DL_STATE_DORMANT or >> > DL_STATE_AVAILABLE to DL_STATE_CONSUMER_PROBE. It also resets the >> > status >> > back to DL_STATE_DORMANT or DL_STATE_AVAILABLE if the consumer probe >> > fails. >> > >> > [1] - https://lore.kernel.org/lkml/20200522204120.3b3c9ed6@apollo/ >> > Fixes: 05ef983e0d65 ("driver core: Add device link support for >> > SYNC_STATE_ONLY flag") >> > Fixes: 21c27f06587d ("driver core: Fix SYNC_STATE_ONLY device link >> > implementation") >> > Reported-by: Michael Walle <michael@walle.cc> >> > Signed-off-by: Saravana Kannan <saravanak@google.com> >> > --- >> > >> > v1->v2: >> > - Added code to "revert" the link status if consumer probe fails >> > >> > Greg, >> > >> > I think this is the issue Michael ran into. I'd like him to test the >> > fix >> > before it's pulled in. >> > >> > Michael, >> > >> > If you can test this on the branch you saw the issue in and give a >> > Tested-by if it works, that'd be great. >> >> with v2 I'm triggering the >> WARN_ON(!(link->status & DL_FLAG_SYNC_STATE_ONLY)); >> in __device_links_no_driver(). > > Thanks for the logs! The WARNING is due to a dump typo in this line. I > should be checking link->flags, not link->status here. I'll send out a > v3, but you can test with this change too.
Ahh, right. With that fix you can add:
Tested-by: Michael Walle <michael@walle.cc>
Thanks, -michael
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