Thu, Oct 15, 2015 at 05:21:22PM CEST, john.fastab...@gmail.com wrote:
>On 15-10-14 10:40 AM, Jiri Pirko wrote:
>> From: Jiri Pirko <j...@mellanox.com>
>>
>> Caller should know if he can call attr_set directly (when holding RTNL)
>> or if he has to defer the att_set processing for later.
>>
>> This also allows drivers to sleep inside attr_set and report operation
>> status back to switchdev core. Switchdev core then warns if status is
>> not ok, instead of silent errors happening in drivers.
>>
>> Benefit from newly introduced switchdev deferred ops infrastructure.
>>
>
>A nit but the patch description should note your setting the defer bit
>on the bridge set state.
>
>> Signed-off-by: Jiri Pirko <j...@mellanox.com>
>> ---
>> include/net/switchdev.h | 1 +
>> net/bridge/br_stp.c | 3 +-
>> net/switchdev/switchdev.c | 108
>> ++++++++++++++++++----------------------------
>> 3 files changed, 46 insertions(+), 66 deletions(-)
>>
>> diff --git a/include/net/switchdev.h b/include/net/switchdev.h
>> index d1c7f90..f7de6f8 100644
>> --- a/include/net/switchdev.h
>> +++ b/include/net/switchdev.h
>> @@ -17,6 +17,7 @@
>>
>> #define SWITCHDEV_F_NO_RECURSE BIT(0)
>> #define SWITCHDEV_F_SKIP_EOPNOTSUPP BIT(1)
>> +#define SWITCHDEV_F_DEFER BIT(2)
>>
>> struct switchdev_trans_item {
>> struct list_head list;
>> diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
>> index db6d243de..80c34d7 100644
>> --- a/net/bridge/br_stp.c
>> +++ b/net/bridge/br_stp.c
>> @@ -41,13 +41,14 @@ void br_set_state(struct net_bridge_port *p, unsigned
>> int state)
>> {
>> struct switchdev_attr attr = {
>> .id = SWITCHDEV_ATTR_ID_PORT_STP_STATE,
>> + .flags = SWITCHDEV_F_DEFER,
>> .u.stp_state = state,
>> };
>
>
>This creates a possible race (with 6/8) I think, please check!
Wait. This patch does not change the previous behaviour. Patch 6 does,
so I don't understand why you are asking here. Confusing.
>
>In del_nbp() we call br_stp_disable_port() to set the port state
>to BR_STATE_DISABLE and disabling learning events. But with this
>patch it can be deferred. Also note the STP agent may be in userspace
>which actually seems more likely the case because you likely want to
>run some more modern variant of STP than the kernel supports.
>
>So at some point in the future the driver will turn off learning. At
>the same time we call br_fdb_delete_by_port which calls a deferred
>set of fdb deletes.
>
>I don't see how you guarantee learning is off before you start doing
>the deletes here and possibly learning new addresses after the software
>side believes the port is down.
>
>So
>
> br_stp_disable_port
> br_fdb_delete_by_port
> {fdb_del_external_learn}
> [hw learns a fdb]
> [hw disables learning]
>
>What stops this from happening?
Okay. This behaviour is the same as without the patchset. What would
resolve the issue it to put switchdev_deferred_process() after
br_stp_disable_port() and before br_fdb_delete_by_port() call.
That would enforce stp change to happen in hw before fdbs are explicitly
deleted. Sound good to you?
>
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