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    SubjectRe: [PATCH v2] driver core: Fix SYNC_STATE_ONLY device link implementation
    On Mon, May 18, 2020 at 08:00:25PM -0700, Saravana Kannan wrote:
    > 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.
    > Cc:
    > Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag")
    > Signed-off-by: Saravana Kannan <>
    > ---
    > drivers/base/core.c | 61 +++++++++++++++++++++++++++++----------------
    > 1 file changed, 39 insertions(+), 22 deletions(-)

    If this is v2, what changed from v1?

    That always goes below the --- line, you know this :)

    v3 please?


    greg k-h

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