[dpdk-dev] [PATCH 05/22] ethdev: introduce device lock

[Zhang, Qi Z]

Hi Stephen:


> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> Sent: Saturday, June 16, 2018 12:09 AM
> To: Zhang, Qi Z <qi.z.zhang at intel.com>
> Cc: thomas at monjalon.net; Burakov, Anatoly <anatoly.burakov at intel.com>;
> Ananyev, Konstantin <konstantin.ananyev at intel.com>; dev at dpdk.org;
> Richardson, Bruce <bruce.richardson at intel.com>; Yigit, Ferruh
> <ferruh.yigit at intel.com>; Shelton, Benjamin H
> <benjamin.h.shelton at intel.com>; Vangati, Narender
> <narender.vangati at intel.com>
> Subject: Re: [dpdk-dev] [PATCH 05/22] ethdev: introduce device lock
> 
> On Thu,  7 Jun 2018 20:38:32 +0800
> Qi Zhang <qi.z.zhang at intel.com> wrote:
> 
> > +/**
> > + * Lock an Ethernet Device directly or register a callback function
> > + * for condition check at runtime, this help application to prevent
> > + * a device be detached unexpectly.
> > + * NOTE: Lock a device mutliple times with same parmeter will increase
> > + * a ref_count, and coresponding unlock decrease the ref_count, the
> > + * device will be unlocked when ref_count reach 0.
> > + *
> > + * @param port_id
> > + *   The port identifier of the Ethernet device.
> > + * @param callback
> > + *   !NULL the callback function will be added into a pre-detach list,
> > + *         it will be invoked when a device is going to be detached. The
> > + *         return value will decide if continue detach the device or not.
> > + *   NULL  lock the device directly, basically this just regiter a empty
> > + *         callback function(dev_is_busy) that return -EBUSY, so we can
> > + *         handle the pre-detach check in unified way.
> > + * @param user_args
> > + *   parameter will be parsed to callback function, only valid when
> > + *   callback != NULL.
> > + * @return
> > + *   0 on success, negative on error.
> > + */
> > +int rte_eth_dev_lock(uint16_t port_id, rte_eth_dev_lock_callback_t
> callback,
> > +		     void *user_args);
> 
> I prefer API's that do one thing with one function.

Agree

> Why not
> 	rte_eth_dev_lock(uint16_t port_id);
> 	rte_eth_dev_ondetach(uint16_t port_id, rte_eth_dev_lock_callback_t
> callback,
>            		     void *user_args);

Rte_eth_dev_ondetach looks like a callback function, 
but this is the function to register some condition check.
How about rte_eth_dev_lock and rte_eth_dev_lock_with_cond?

Thanks
Qi