Re: [dpdk-dev] [PATCH v2] ethdev: avoid usage of uninit device info in bad port case

[Thomas Monjalon <thomas@monjalon.net>]

23/07/2019 15:34, Andrew Rybchenko:
> On 7/23/19 4:14 PM, Thomas Monjalon wrote:
> > 23/07/2019 14:11, Andrew Rybchenko:
> >> rte_eth_dev_info_get() returns void and caller does know if the function
> >> does its job or not. Changing of the return value to int would be
> >> API/ABI breakage which requires deprecation process and cannot be
> >> backported to stable branches. For now, make sure that device info is
> >> initialized even in the case of invalid port ID.
> >>
> >> Fixes: a30268e9a2d0 ("ethdev: reset whole dev info structure before filling")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
> >> ---
> >> --- a/lib/librte_ethdev/rte_ethdev.c
> >> +++ b/lib/librte_ethdev/rte_ethdev.c
> >> +	/*
> >> +	 * Init dev_info before port_id check since caller does not have
> >> +	 * return status and does not know if get is successful or not.
> >> +	 */
> >> +	memset(dev_info, 0, sizeof(struct rte_eth_dev_info));
> > If someone was using a canary to detect failure, it will be resetted.
> 
> I've not thought about such ways to check. I would expected check
> for not NULL device or driver_name. It is not defined behaviour of
> the function to not touch dev_info in the case of bad port ID.
> 
> > Why is it urgent to have this workaround?
> 
> Nothing really urgent, but I still think that it is a right fix to be
> applied and backported to stable branches.
> I really met calls with invalid port ID and it took some time
> to understand where uninitialized data come from.
> 
> > Can we wait one more release for the definitive fix with error code?
> 
> No strong opinion, but definitive fix will not be backported.

You're right.
Acked-by: Thomas Monjalon <thomas@monjalon.net>