Re: [PATCH v3] driver core: Fix SYNC_STATE_ONLY device link implementation

From: Michael Walle
Date: Mon May 25 2020 - 07:31:38 EST

Am 2020-05-23 00:47, schrieb Michael Walle:
Am 2020-05-23 00:21, schrieb Saravana Kannan:
On Fri, May 22, 2020 at 11:41 AM Michael Walle <michael@xxxxxxxx> wrote:

Am Mon, 18 May 2020 23:30:00 -0700
schrieb Saravana Kannan <saravanak@xxxxxxxxxx>:

> When SYNC_STATE_ONLY support was added in commit 05ef983e0d65 ("driver
> core: Add device link support for SYNC_STATE_ONLY flag"),
> device_link_add() incorrectly skipped adding the new SYNC_STATE_ONLY
> device link to the supplier's and consumer's "device link" list.
> This causes multiple issues:
> - The device link is lost forever from driver core if the caller
> didn't keep track of it (caller typically isn't expected to). This
> is a memory leak.
> - The device link is also never visible to any other code path after
> device_link_add() returns.
> If we fix the "device link" list handling, that exposes a bunch of
> issues.
> 1. The device link "status" state management code rightfully doesn't
> handle the case where a DL_FLAG_MANAGED device link exists between a
> supplier and consumer, but the consumer manages to probe successfully
> before the supplier. The addition of DL_FLAG_SYNC_STATE_ONLY links
> break this assumption. This causes device_links_driver_bound() to
> throw a warning when this happens.
> Since DL_FLAG_SYNC_STATE_ONLY device links are mainly used for
> creating proxy device links for child device dependencies and aren't
> useful once the consumer device probes successfully, this patch just
> deletes DL_FLAG_SYNC_STATE_ONLY device links once its consumer device
> probes. This way, we avoid the warning, free up some memory and avoid
> complicating the device links "status" state management code.
> 2. Creating a DL_FLAG_STATELESS device link between two devices that
> already have a DL_FLAG_SYNC_STATE_ONLY device link will result in the
> DL_FLAG_STATELESS flag not getting set correctly. This patch also
> fixes this.
> Lastly, this patch also fixes minor whitespace issues.

My board triggers the

Full bootlog:

Thanks for the log and report. I haven't spent too much time thinking
about this, but can you give this a shot?

I've already tried that, as this is already in linux-next. Doesn't fix it,

btw. this only happens on linux-next (tested with next-20200522), not on
5.7-rc7 (which has the same two patches of yours)