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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Petr Machata , Ido Schimmel , bridge@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240830145356.102951-1-jonas.gorski@bisdn.de> Content-Language: en-US From: Nikolay Aleksandrov In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 01/09/2024 14:54, Ido Schimmel wrote: > On Sat, Aug 31, 2024 at 11:31:50AM +0300, Nikolay Aleksandrov wrote: >> On 30/08/2024 17:53, Jonas Gorski wrote: >>> When userspace wants to take over a fdb entry by setting it as >>> EXTERN_LEARNED, we set both flags BR_FDB_ADDED_BY_EXT_LEARN and >>> BR_FDB_ADDED_BY_USER in br_fdb_external_learn_add(). >>> >>> If the bridge updates the entry later because its port changed, we clear >>> the BR_FDB_ADDED_BY_EXT_LEARN flag, but leave the BR_FDB_ADDED_BY_USER >>> flag set. >>> >>> If userspace then wants to take over the entry again, >>> br_fdb_external_learn_add() sees that BR_FDB_ADDED_BY_USER and skips >>> setting the BR_FDB_ADDED_BY_EXT_LEARN flags, thus silently ignores the >>> update: >>> >>> if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) { >>> /* Refresh entry */ >>> fdb->used = jiffies; >>> } else if (!test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags)) { >>> /* Take over SW learned entry */ >>> set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags); >>> modified = true; >>> } >>> >>> Fix this by relaxing the condition for setting BR_FDB_ADDED_BY_EXT_LEARN >>> by also allowing it if swdev_notify is true, which it will only be for >>> user initiated updates. >>> >>> Fixes: 710ae7287737 ("net: bridge: Mark FDB entries that were added by user as such") >>> Signed-off-by: Jonas Gorski >>> --- >>> net/bridge/br_fdb.c | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c >>> index c77591e63841..c5d9ae13a6fb 100644 >>> --- a/net/bridge/br_fdb.c >>> +++ b/net/bridge/br_fdb.c >>> @@ -1472,7 +1472,8 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p, >>> if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) { >>> /* Refresh entry */ >>> fdb->used = jiffies; >>> - } else if (!test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags)) { >>> + } else if (swdev_notify || >>> + !test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags)) { >>> /* Take over SW learned entry */ >>> set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags); >>> modified = true; >> >> This literally means if added_by_user || !added_by_user, so you can probably >> rewrite that whole block to be more straight-forward with test_and_set_bit - >> if it was already set then refresh, if it wasn't modified = true > > Hi Nik, > > You mean like this [1]? > I deleted the comment about "SW learned entry" since "extern_learn" flag > not being set does not necessarily mean the entry was learned by SW. > > [1] > diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c > index c77591e63841..ad7a42b505ef 100644 > --- a/net/bridge/br_fdb.c > +++ b/net/bridge/br_fdb.c > @@ -1469,12 +1469,10 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p, > modified = true; > } > > - if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) { > + if (test_and_set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) { > /* Refresh entry */ > fdb->used = jiffies; > - } else if (!test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags)) { > - /* Take over SW learned entry */ > - set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags); > + } else { > modified = true; > } Yeah, that's exactly what I meant. Since the added_by_user condition becomes redundant we can just drop it.