Re: [PATCH net-next v3 01/11] net/smc: adapt SMC-D device dump for Emulated-ISM
From: Wen Gu
Date: Thu Mar 14 2024 - 23:44:38 EST
On 2024/3/14 18:23, Jan Karcher wrote:
On 12/03/2024 15:27, Wen Gu wrote:
The introduction of Emulated-ISM requires adaptation of SMC-D device
dump. Software implemented non-PCI device (loopback-ism) should be
handled correctly and the CHID reserved for Emulated-ISM should be got
from smcd_ops interface instead of PCI information.
Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
---
net/smc/smc_ism.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
index ac88de2a06a0..b6eca4231913 100644
--- a/net/smc/smc_ism.c
+++ b/net/smc/smc_ism.c
@@ -252,12 +252,11 @@ static int smc_nl_handle_smcd_dev(struct smcd_dev *smcd,
char smc_pnet[SMC_MAX_PNETID_LEN + 1];
struct smc_pci_dev smc_pci_dev;
struct nlattr *port_attrs;
+ struct device *device;
struct nlattr *attrs;
- struct ism_dev *ism;
int use_cnt = 0;
void *nlh;
- ism = smcd->priv;
nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
&smc_gen_nl_family, NLM_F_MULTI,
SMC_NETLINK_GET_DEV_SMCD);
@@ -272,7 +271,15 @@ static int smc_nl_handle_smcd_dev(struct smcd_dev *smcd,
if (nla_put_u8(skb, SMC_NLA_DEV_IS_CRIT, use_cnt > 0))
goto errattr;
memset(&smc_pci_dev, 0, sizeof(smc_pci_dev));
- smc_set_pci_values(to_pci_dev(ism->dev.parent), &smc_pci_dev);
+ device = smcd->ops->get_dev(smcd);
+ if (device->parent)
+ smc_set_pci_values(to_pci_dev(device->parent), &smc_pci_dev);
+ if (smc_ism_is_emulated(smcd)) {
+ smc_pci_dev.pci_pchid = smc_ism_get_chid(smcd);
+ if (!device->parent)
+ snprintf(smc_pci_dev.pci_id, sizeof(smc_pci_dev.pci_id),
+ "%s", dev_name(device));
+ }
Hi Wen Gu,
playing around with the loopback-ism device and testing it, i developed some concerns regarding this exposure. Basically
this enables us to see the loopback device in the `smcd device` tool without any changes.
E.g.:
```
# smcd device
FID Type PCI-ID PCHID InUse #LGs PNET-ID
0000 0 loopback-ism ffff No 0
102a ISM 0000:00:00.0 07c2 No 0 NET1
```
Now the problem with this is that "loopback-ism" is no valid PCI-ID and should not be there. My first thought was to put
an "n/a" instead, but that opens up another problem. Currently you could set - even if it does not make sense - a
PNET_ID for the loopback device:
```
Yes, and we can exclude loopback-ism in smc_pnet_enter() if necessary.
# smc_pnet -a -D loopback-ism NET1
# smcd device
FID Type PCI-ID PCHID InUse #LGs PNET-ID
0000 0 loopback-ism ffff No 0 *NET1
102a ISM 0000:00:00.0 07c2 No 0 NET1
```
If we would change the PCI-ID to "n/a" it would be a valid input parameter for the tooling which is... to put it nice...
not so beautiful.
FID Type PCI-ID PCHID InUse #LGs PNET-ID
0000 0 n/a ffff No 0
IIUC, the problem is that the 'n/a', which would be an input for other tools, is somewhat strange?
Since PCHID 0xffff is clear defined for loopback-ism, I am wondering if it can be a specific sign
of loopback-ism for tooling to not take PCI-ID into account? Would you also consider that inelegant?
I brainstormed this with them team and the problem is more complex.
In theory there shouldn't be PCI information set for the loopback device. There should be a better abstraction in the
netlink interface that creates this output and the tooling should be made aware of it.
Yes, it is better. But I couldn't surely picture how the abstraction looks like, and if it is necessary
to introduce it just for a special case of loopback-ism (note that virtio-ISM also has PCI information),
since we can identify loopback-ism by CHID.
Do you rely on the output currently? What are your thoughts about it?
If not I'd ask you to not fill the netlink interface for the loopback device and refactor it with the next stage when we
create a right interface for it.
Currently we don't rely on the output, and I have no objection to the proposal that not fill the netlink
interface for loopback-ism and refactor it in the next stage.
Since the Merge-Window is closed feel free to send new versions as RFC.
OK, I will send the new version as an RFC.
Thank you!
Thank you
- Jan
if (nla_put_u32(skb, SMC_NLA_DEV_PCI_FID, smc_pci_dev.pci_fid))
goto errattr;
if (nla_put_u16(skb, SMC_NLA_DEV_PCI_CHID, smc_pci_dev.pci_pchid))