From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH] ethdev: remove useless parameter in callback
	process
Date: Thu, 28 Dec 2017 22:56:35 +0100
Message-ID: <2205083.4lcr8qjecY@xps>
References: <20171128220951.15317-1-thomas@monjalon.net>
 <53c8669c-79b9-2f6d-4008-7679aa2cf377@intel.com> <1953628.EychQmWvfA@xps>
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Cc: bernard.iremonger@intel.com
To: dev@dpdk.org, Ferruh Yigit <ferruh.yigit@intel.com>
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28/12/2017 22:54, Thomas Monjalon:
> 22/12/2017 04:08, Ferruh Yigit:
> > On 11/28/2017 2:09 PM, Thomas Monjalon wrote:
> > > The pointer to the user parameter of the callback registration is
> > > automatically pass to the callback function.
> > > There is no point to allow changing this user parameter by a caller.
> > > That's why this parameter is always set to NULL by PMDs and set only
> > > in ethdev layer before calling the callback function.
> > 
> > It can be helpful to mention a little from history:
> > 
> > user cb_arg overwrite introduced by [1], to enable driver pass a pointer to user
> > callback function and carry some information back from app to driver.
> > 
> > Later to prevent usage of cb_arg as both input and output, an explicit output
> > (ret_param) added [2] to _rte_eth_dev_callback_process() but previous cb_arg
> > overwriting kept without any user.
> > 
> > [1]: c1ceaf3ad056 ("ethdev: add an argument to internal callback function")
> > 
> > [2]: d6af1a13d7a1 ("ethdev: add return values to callback process API")
> > 
> > > 
> > > The NULL parameter in the internal callback processing function
> > > is now removed. It makes clear that the callback parameter is user
> > > managed and opaque from a DPDK point of view.
> > > 
> > > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > 
> > Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
> 
> Applied

Sorry, not applied (should be applied on next-net).

I will send a v2 with a more detailed explanation.