Messages in this thread | | | Date | Sat, 23 May 2020 00:47:39 +0200 | From | Michael Walle <> | Subject | Re: [PATCH v3] driver core: Fix SYNC_STATE_ONLY device link implementation |
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Am 2020-05-23 00:21, schrieb Saravana Kannan: > On Fri, May 22, 2020 at 11:41 AM Michael Walle <michael@walle.cc> > wrote: >> >> Am Mon, 18 May 2020 23:30:00 -0700 >> schrieb Saravana Kannan <saravanak@google.com>: >> >> > 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 >> WARN_ON(link->status != DL_STATE_CONSUMER_PROBE); >> >> 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? > https://lore.kernel.org/lkml/20200520043626.181820-1-saravanak@google.com/
I've already tried that, as this is already in linux-next. Doesn't fix it, though.
-michael
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