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Date: Sun, 31 Oct 2021 08:29:20 +0200 From: Leon Romanovsky <leon@...nel.org> To: Jakub Kicinski <kuba@...nel.org> Cc: davem@...emloft.net, netdev@...r.kernel.org, jiri@...nulli.us, mkubecek@...e.cz, andrew@...n.ch, f.fainelli@...il.com Subject: Re: [PATCH net-next v2 3/4] devlink: expose get/put functions On Sat, Oct 30, 2021 at 10:18:50AM -0700, Jakub Kicinski wrote: > Allow those who hold implicit reference on a devlink instance > to try to take a full ref on it. This will be used from netdev > code which has an implicit ref because of driver call ordering. > > Note that after recent changes devlink_unregister() may happen > before netdev unregister, but devlink_free() should still happen > after, so we are safe to try, but we can't just refcount_inc() > and assume it's not zero. > > Signed-off-by: Jakub Kicinski <kuba@...nel.org> > --- > include/net/devlink.h | 12 ++++++++++++ > net/core/devlink.c | 8 +++++--- > 2 files changed, 17 insertions(+), 3 deletions(-) I really like this series, but your latest netdevsim RFC made me worry. It is important to make sure that these devlink_put() and devlink_get() calls will be out-of-reach from the drivers. Only core code should use them. Can you please add it as a comment above these functions? At least for now, till we discuss your RFC. Reviewed-by: Leon Romanovsky <leonro@...dia.com> Thanks > > diff --git a/include/net/devlink.h b/include/net/devlink.h > index 1b1317d378de..991ce48f77ca 100644 > --- a/include/net/devlink.h > +++ b/include/net/devlink.h > @@ -1726,6 +1726,9 @@ devlink_trap_policers_unregister(struct devlink *devlink, > > #if IS_ENABLED(CONFIG_NET_DEVLINK) > > +struct devlink *__must_check devlink_try_get(struct devlink *devlink); > +void devlink_put(struct devlink *devlink); > + > void devlink_compat_running_version(struct net_device *dev, > char *buf, size_t len); > int devlink_compat_flash_update(struct net_device *dev, const char *file_name); > @@ -1736,6 +1739,15 @@ int devlink_compat_switch_id_get(struct net_device *dev, > > #else > > +static inline struct devlink *devlink_try_get(struct devlink *devlink) > +{ > + return NULL; > +} > + > +static inline void devlink_put(struct devlink *devlink) > +{ > +} > + > static inline void > devlink_compat_running_version(struct net_device *dev, char *buf, size_t len) > { > diff --git a/net/core/devlink.c b/net/core/devlink.c > index 2d8abe88c673..100d87fd3f65 100644 > --- a/net/core/devlink.c > +++ b/net/core/devlink.c > @@ -182,15 +182,17 @@ struct net *devlink_net(const struct devlink *devlink) > } > EXPORT_SYMBOL_GPL(devlink_net); > > -static void devlink_put(struct devlink *devlink) > +void devlink_put(struct devlink *devlink) > { > if (refcount_dec_and_test(&devlink->refcount)) > complete(&devlink->comp); > } > > -static bool __must_check devlink_try_get(struct devlink *devlink) > +struct devlink *__must_check devlink_try_get(struct devlink *devlink) > { > - return refcount_inc_not_zero(&devlink->refcount); > + if (refcount_inc_not_zero(&devlink->refcount)) > + return devlink; > + return NULL; > } > > static struct devlink *devlink_get_from_attrs(struct net *net, > -- > 2.31.1 >
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