[dpdk-dev] [PATCH 04/22] ethdev: enable hotplug on multi-process

[Burakov, Anatoly]

On 07-Jun-18 1:38 PM, Qi Zhang wrote:
> The patch 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, it will be implemented in
> following separate patch.
> 
> 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 3, 4:
> This will be implemented in following patch.
> 
> 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 allowd 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 chenages:
> 
> 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.zhang at intel.com>
> ---
>   lib/librte_eal/common/eal_private.h   |   8 ++
>   lib/librte_eal/linuxapp/eal/eal.c     |   6 ++
>   lib/librte_ethdev/Makefile            |   1 +
>   lib/librte_ethdev/rte_ethdev.c        | 183 ++++++++++++++++++++++++++++---
>   lib/librte_ethdev/rte_ethdev.h        |  37 +++++++
>   lib/librte_ethdev/rte_ethdev_core.h   |   5 +
>   lib/librte_ethdev/rte_ethdev_driver.h |  27 +++++
>   lib/librte_ethdev/rte_ethdev_mp.c     | 195 ++++++++++++++++++++++++++++++++++
>   lib/librte_ethdev/rte_ethdev_mp.h     |  44 ++++++++
>   9 files changed, 489 insertions(+), 17 deletions(-)
>   create mode 100644 lib/librte_ethdev/rte_ethdev_mp.c
>   create mode 100644 lib/librte_ethdev/rte_ethdev_mp.h
> 

Haven't looked at the code yet, but general comment: please don't prefix 
internal-only files with rte_, it makes it look like they are part of 
external API.

-- 
Thanks,
Anatoly