On Sun, 2 Feb 2025, Ma Ke wrote:
> When device_register(&child->dev) failed, we should call put_device()
> to explicitly release child->dev.
>
> As comment of device_register() says, 'NOTE: _Never_ directly free
> @dev after calling this function, even if it returned an error! Always
> use put_device() to give up the reference initialized in this function
> instead.'
>
> Found by code review.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 4f535093cf8f ("PCI: Put pci_dev in device tree as early as possible")
> Signed-off-by: Ma Ke <make24@xxxxxxxxxxx>
> ---
> Changes in v3:
> - modified the description as suggestions.
> Changes in v2:
> - added the bug description about the comment of device_add();
> - fixed the patch as suggestions;
> - added Cc and Fixes table.
> ---
> drivers/pci/probe.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 2e81ab0f5a25..51b78fcda4eb 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1174,7 +1174,10 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
> add_dev:
> pci_set_bus_msi_domain(child);
> ret = device_register(&child->dev);
> - WARN_ON(ret < 0);
> + if (WARN_ON(ret < 0)) {
> + put_device(&child->dev);
> + return NULL;
> + }
>
> pcibios_add_bus(child);
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Unrelated to this fix, IMO that WARN_ON() is overkill and I'm skeptical
that printing a stack trace on a failure in device_register() is helpful.
IMO, a simple error print would suffice to tell something (unexpectedly)
went wrong here.
--
i.
