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@vger.kernel.org Fixes: 4f535093cf8f ("PCI: Put pci_dev in device tree as early as possible") Signed-off-by: Ma Ke make24@iscas.ac.cn

---

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@linux.intel.com

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.