Re: [PATCH AUTOSEL 5.6 14/68] driver core: Reevaluate dev->links.need_for_probe as suppliers are added

Greg Kroah-Hartman
2020-04-10T06:29:49Z

On Thu, Apr 09, 2020 at 11:45:39PM -0400, Sasha Levin wrote:
> From: Saravana Kannan <saravanak@google.com>
>
> [ Upstream commit 1745d299af5b373abad08fa29bff0d31dc6aff21 ]
>
> A previous patch 03324507e66c ("driver core: Allow
> fwnode_operations.add_links to differentiate errors") forgot to update
> all call sites to fwnode_operations.add_links. This patch fixes that.
>
> Legend:
> -> Denotes RHS is an optional/potential supplier for LHS
> => Denotes RHS is a mandatory supplier for LHS
>
> Example:
>
> Device A => Device X
> Device A -> Device Y
>
> Before this patch:
> 1. Device A is added.
> 2. Device A is marked as waiting for mandatory suppliers
> 3. Device X is added
> 4. Device A is left marked as waiting for mandatory suppliers
>
> Step 4 is wrong since all mandatory suppliers of Device A have been
> added.
>
> After this patch:
> 1. Device A is added.
> 2. Device A is marked as waiting for mandatory suppliers
> 3. Device X is added
> 4. Device A is no longer considered as waiting for mandatory suppliers
>
> This is the correct behavior.
>
> Fixes: 03324507e66c ("driver core: Allow fwnode_operations.add_links to differentiate errors")
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> Link: https://lore.kernel.org/r/20200222014038.180923-2-saravanak@google.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/base/core.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index dbb0f9130f42d..d32a3aefff32f 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -523,9 +523,13 @@ static void device_link_add_missing_supplier_links(void)
>
> mutex_lock(&wfs_lock);
> list_for_each_entry_safe(dev, tmp, &wait_for_suppliers,
> - links.needs_suppliers)
> - if (!fwnode_call_int_op(dev->fwnode, add_links, dev))
> + links.needs_suppliers) {
> + int ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
> + if (!ret)
> list_del_init(&dev->links.needs_suppliers);
> + else if (ret != -ENODEV)
> + dev->links.need_for_probe = false;
> + }
> mutex_unlock(&wfs_lock);
> }

For some reason this wasn't for stable kernels, but I can't remember.

Saravana, any thoughts?

greg k-h