Re: [PATCH net-next v2 3/4] devlink: expose get/put functions
flat view
From: Leon Romanovsky <leon@kernel.org>
Date: 2021-10-31 06:29:25
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@kernel.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@nvidia.com> Thanks
quoted hunk ↗ jump to hunk
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