-----Original Message-----
From: Burakov, Anatoly
Sent: Tuesday, June 26, 2018 8:09 PM
To: Zhang, Qi Z <qi.z.zh...@intel.com>; tho...@monjalon.net
Cc: Ananyev, Konstantin <konstantin.anan...@intel.com>; dev@dpdk.org;
Richardson, Bruce <bruce.richard...@intel.com>; Yigit, Ferruh
<ferruh.yi...@intel.com>; Shelton, Benjamin H
<benjamin.h.shel...@intel.com>; Vangati, Narender
<narender.vang...@intel.com>
Subject: Re: [PATCH v4 06/24] ethdev: enable hotplug on multi-process
On 26-Jun-18 8:08 AM, Qi Zhang wrote:
We are going to introduce the solution to handle different hotplug
cases in multi-process situation, it include below scenario:
1. Attach a share device from primary
2. Detach a share device from primary
3. Attach a share device from secondary 4. Detach a share device from
secondary 5. Attach a private device from secondary 6. Detach a
private device from secondary 7. Detach a share device from secondary
privately 8. Attach a share device from secondary privately
In primary-secondary process model, we assume device is shared by default.
that means attach or detach a device on any process will broadcast to
all other processes through mp channel then device information will be
synchronized on all processes.
Any failure during attaching process will cause inconsistent status
between processes, so proper rollback action should be considered.
Also it is not safe to detach a share device when other process still
use it, so a handshake mechanism is introduced.
This patch covers the implementation of case 1,2,5,6,7,8.
Case 3,4 will be implemented on separate patch as well as handshake
mechanism.
Scenario for Case 1, 2:
attach device
a) primary attach the new device if failed goto h).
b) primary send attach sync request to all secondary.
c) secondary receive request and attach device and send reply.
d) primary check the reply if all success go to i).
e) primary send attach rollback sync request to all secondary.
f) secondary receive the request and detach device and send reply.
g) primary receive the reply and detach device as rollback action.
h) attach fail
i) attach success
detach device
a) primary perform pre-detach check, if device is locked, goto i).
b) primary send pre-detach sync request to all secondary.
c) secondary perform pre-detach check and send reply.
d) primary check the reply if any fail goto i).
e) primary send detach sync request to all secondary
f) secondary detach the device and send reply (assume no fail)
g) primary detach the device.
h) detach success
i) detach failed
Case 5, 6:
Secondary process can attach private device which only visible to
itself, in this case no IPC is involved, primary process is not
allowed to have private device so far.
Case 7, 8:
Secondary process can also temporally to detach a share device "privately"
then attach it back later, this action also not impact other processes.
APIs changes:
rte_eth_dev_attach and rte_eth_dev_attach are extended to support
share device attach/detach in primary-secondary process model, it will
be called in case 1,2,3,4.
New API rte_eth_dev_attach_private and rte_eth_dev_detach_private are
introduced to cover case 5,6,7,8, this API can only be invoked in
secondary process.
Signed-off-by: Qi Zhang <qi.z.zh...@intel.com>
---
<snip>
+static int
+handle_primary_request(const struct rte_mp_msg *msg, const void
+*peer) {
+
+ struct rte_mp_msg mp_resp;
+ const struct eth_dev_mp_req *req =
+ (const struct eth_dev_mp_req *)msg->param;
+ struct eth_dev_mp_req *resp =
+ (struct eth_dev_mp_req *)mp_resp.param;
+ struct mp_reply_bundle *bundle;
+ int ret = 0;
+
+ memset(&mp_resp, 0, sizeof(mp_resp));
+ strlcpy(mp_resp.name, ETH_DEV_MP_ACTION_REQUEST,
sizeof(mp_resp.name));
+ mp_resp.len_param = sizeof(*req);
+ memcpy(resp, req, sizeof(*resp));
+
+ bundle = calloc(1, sizeof(*bundle));
+ if (bundle == NULL) {
+ resp->result = -ENOMEM;
+ ret = rte_mp_reply(&mp_resp, peer);
+ if (ret) {
+ ethdev_log(ERR, "failed to send reply to primary
request\n");
+ return ret;
+ }
+ }
+
+ bundle->msg = *msg;
+ bundle->peer = peer;
+
+ ret = rte_eal_mp_task_add(__handle_primary_request, bundle);
+ if (ret) {
+ resp->result = ret;
+ ret = rte_mp_reply(&mp_resp, peer);
+ if (ret) {
+ ethdev_log(ERR, "failed to send reply to primary
request\n");
+ return ret;
+ }
+ }
What you're doing here is quite dangerous. The parameter "const void *peer"
is only guaranteed to be valid at the time of the callback - not necessarily
afterwards. So, if you're handing off sending replies to a separate thread,
things might blow up because the pointer may no longer be valid.
