[dpdk-dev] [PATCH v8 1/5] ethdev: add support of NIC reset

[Remy Horton]

See suggested wording inline

On 17/07/2017 16:14, Wei Dai wrote:
> This patch adds a new eth_dev layer API function rte_eth_dev_reset().
> A DPDK application can call this function to reset a NIC and keep
> its port id afterwards.
> It means that all SW resources allocated in ethdev layer should be
> kept and SW and HW resources of the NIC in PMD need to be reset in
> similar way that it runs PCI dev_uninit() and then dev_init().
> The sequence of dev_uninit() and dev_init() can be packed into a
> single interface API rte_eth_dev_reset().
> Please See the comments before the declaration of rte_eht_dev_reset()
> in lib/librte_ether/rte_ethdev.h to get more details on why this
> function is needed, what it does, when it should be called
> and what an application should do after calling this function.

This patch adds a new eth_dev layer API function rte_eth_dev_reset(),
which a DPDK application can call to reset a NIC and keep its port id
afterwards. It means that all software resources allocated in the ethdev 
layer are kept, and software & hardware resources of the NIC within the 
NIC's PMD are reset to a state simular to that obtained by calling the 
PCI dev_uninit() and then dev_init(). This effective sequence of 
dev_uninit() and dev_init() is packed into a single API function 
rte_eth_dev_reset().

Please see the comments before the declaration of rte_eht_dev_reset()
in lib/librte_ether/rte_ethdev.h to get more details on why this
function is needed, what it does, when it should be called
and what an application should do after calling this function.


> Signed-off-by: Wei Dai <wei.dai at intel.com>
> ---
>  lib/librte_ether/rte_ethdev.c          | 17 +++++++++++++++++
>  lib/librte_ether/rte_ethdev.h          | 33 +++++++++++++++++++++++++++++++++
>  lib/librte_ether/rte_ether_version.map |  1 +
>  3 files changed, 51 insertions(+)

Reviewed-by: Remy Horton <remy.horton at intel.com>



>  /**
> + * Reset a Ethernet device and keep its port id.
> + *
> + * When a port has to be reset passively, the DPDK application can invoke this
> + * function. For example a PF is reset, all its VFs should also be reset.
> + * Normally, a DPDK application can invoke this function when
> + * RTE_ETH_EVENT_INTR_RESET event is detected. A DPDK application can also call
> + * this function to start an initiative port reset.

When a port has to be reset passively, the DPDK application can invoke 
this function. For example when a PF is reset, all its VFs should also 
be reset. Normally a DPDK application can invoke this function when 
RTE_ETH_EVENT_INTR_RESET event is detected, but can also use it to start 
a port reset in other circumstances.

> + * When this function is called, it first stops the port and then call PMD
> + * specific dev_uninit( ) and  dev_init( ) to makes the port return to initial
> + * status in which no any Tx queue and no Rx queue are setup and the port has
> + * just be reset and not started. And the port keeps its port id after calling
> + * this function.

When this function is called, it first stops the port and then calls the 
PMD specific dev_uninit( ) and dev_init( ) to return the port to initial 
state, in which no Tx and Rx queues are setup, as if the port has been 
reset and not started. The port keeps the port id it had before the 
function call.

> + * After calling rte_eth_dev_reset( ), the application should go through
> + * rte_eth_dev_configure( ), rte_eth_rx_queue_setup( ),
> + * rte_eth_tx_queue_setup( ) and rte_eth_dev_start( ) again to restore
> + * its previous settings or to reconfigure itself with different settings.

After calling rte_eth_dev_reset( ), the application should use
rte_eth_dev_configure( ), rte_eth_rx_queue_setup( ),
rte_eth_tx_queue_setup( ), and rte_eth_dev_start( )
to reconfigure the device as appropriate.


> + * Note: to avoid unexpected behaviour, the application should stop calling Rx
> + *       and Rx function before calling rte_eth_dev_reset( ).For thread safety,
> + *       all these controlling operations had better be made in same thread.

Note: To avoid unexpected behavior, the application should stop calling 
Tx and Rx functions before calling rte_eth_dev_reset( ). For thread 
safety, all these controlling functions should be called from the same 
thread.