On 10/9/2019 9:48 AM, Hyong Youb Kim (hyonkim) wrote: >> -----Original Message----- >> From: Ferruh Yigit <[email protected]> >> Sent: Wednesday, October 9, 2019 5:02 PM >> To: Hyong Youb Kim (hyonkim) <[email protected]> >> Cc: [email protected]; John Daley (johndale) <[email protected]>; Dirk- >> Holger Lenz <[email protected]>; [email protected] >> Subject: Re: [PATCH 1/3] net/enic: restrict several handlers to primary >> process >> >> On 9/6/2019 7:50 AM, Hyong Youb Kim wrote: >>> These eth_dev_ops handlers should run only in the primary process. >>> - filter_ctrl >>> - reta_update >>> - rss_hash_update >>> - set_mc_addr_list >>> - udp_tunnel_port_add >>> - udp_tunnel_port_del >>> >>> Fixes: c2fec27b5cb0 ("net/enic: allow to change RSS settings") >>> Fixes: 8d496995346c ("net/enic: support multicast filtering") >>> Fixes: 8a4efd17410c ("net/enic: add handlers to add/delete vxlan port >> number") >>> Cc: [email protected] >>> >>> Reported-by: Dirk-Holger Lenz <[email protected]> >>> Signed-off-by: Hyong Youb Kim <[email protected]> >>> Tested-by: Dirk-Holger Lenz <[email protected]> >>> Reviewed-by: John Daley <[email protected]> >>> --- >>> drivers/net/enic/enic_ethdev.c | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/drivers/net/enic/enic_ethdev.c >> b/drivers/net/enic/enic_ethdev.c >>> index 06dc67122..85d785e62 100644 >>> --- a/drivers/net/enic/enic_ethdev.c >>> +++ b/drivers/net/enic/enic_ethdev.c >>> @@ -129,6 +129,8 @@ enicpmd_dev_filter_ctrl(struct rte_eth_dev *dev, >>> { >>> int ret = 0; >>> >>> + if (rte_eal_process_type() != RTE_PROC_PRIMARY) >>> + return -E_RTE_SECONDARY; >>> ENICPMD_FUNC_TRACE(); >>> >>> switch (filter_type) { >> >> I remember we have similar talk with John in the past about these secondary >> application checks in ethdev_ops. >> >> I would like to understand why these checks required only in enic, can you >> please describe your use case? >> Is there any reason secondary application can't change configuration of the >> device, or are you updating your driver to work with specific application? > > Hi, > > No fundamental reasons why secondary processes cannot run these > handlers. These checks are to make it clear that it is not safe to do > so at the moment. It is a software limitation. > > The firmware API (devcmd) we use to configure NIC settings assumes one > user executing one command at a time. And, many of the handlers in the > driver also assume primary process. The firmware itself has > enough checks to prevent concurrent devcmd attempts from corrupting > its internal state. But, host processes can get confused. For example, > process A gets process B's results, or overwrites B's devcmd, etc. > > I believe these issues are all fixable in the driver. We could use > locks in shared memory to serialize devcmd (though risky), fix > handlers that assume primary process, and so on. It is a to-do item for > this driver and would require its own patch series (e.g. allow > secondary processes to run X, Y, Z safely)..
What you have described is valid concern for all drivers, that synchronization has been pushed to the application level. I don't see the point of just putting protection to only one driver. And as a alternative, what do you think about having a check in the prob for the secondary process and assign a subset of the ethdev_ops in that case? This makes more clear what is supported in the secondary process, and it prevents putting secondary process checks everywhere.
