On Tue, 17 Dec 2024, Ma Ke wrote:
> When device_register(&child->dev) failed, calling put_device() to
> explicitly release child->dev. Otherwise, it could cause double free
> problem.
>
> 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 <make_ruc2021@xxxxxxx>
> ---
> 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..d3146c588d7f 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 (ret) {
> + WARN_ON(ret < 0);
The usual way is:
if (WARN_ON(ret < 0))
> + put_device(&child->dev);
> + }
>
> pcibios_add_bus(child);
But more serious problem here is that should this code even proceed as if
nothing happened when an error occurs? pci_register_host_bridge() does
proper rollback when device_register() fails but this function doesn't.
Into the same vein, is using WARN_ON() even correct here? Why should this
print a stacktrace if device_register() fails instead of simply printing
and error?
--
i.
