Re: [PATCH net-next] xfrm: use net device refcount tracker helpers

On Tue, Dec 07, 2021 at 11:32:03AM -0800, Eric Dumazet wrote:

From: Eric Dumazet <redacted>

xfrm4_fill_dst() and xfrm6_fill_dst() build dst,
getting a device reference that will likely be released
by standard dst_release() code.

We have to track these references or risk a warning if
CONFIG_NET_DEV_REFCNT_TRACKER=y

Note to XFRM maintainers :

Error path in xfrm6_fill_dst() releases the reference,
but does not clear xdst->u.dst.dev, so I wonder
if this could lead to double dev_put() in some cases,
where a dst_release() _is_ called by the callers in their
error path.

Yes, looks like it can, so this should be fixed.

This extra dev_put() was added in commit 84c4a9dfbf430 ("xfrm6:
release dev before returning error")

Fixes: 9038c320001d ("net: dst: add net device refcount tracking to dst_entry")
Signed-off-by: Eric Dumazet <redacted>
Cc: Cong Wang <redacted>
Cc: Steffen Klassert <steffen.klassert@secunet.com>

As the refcount tracking infrastructure is not yet in ipsec-next:

Acked-by: Steffen Klassert <steffen.klassert@secunet.com>

Thanks!