Re: [dpdk-stable] [dpdk-dev] [PATCH] app/testpmd: fix Segment fault when start fwd

["Wang, ShougangX" <shougangx.wang@intel.com>]

Hi Regards, Ferruh

> -----Original Message-----
> From: Iremonger, Bernard
> Sent: Monday, September 23, 2019 10:18 PM
> To: Yigit, Ferruh <ferruh.yigit@intel.com>; Wang, ShougangX
> <shougangx.wang@intel.com>; dev@dpdk.org
> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Yang, Qiming
> <qiming.yang@intel.com>; stable@dpdk.org
> Subject: RE: [dpdk-dev] [dpdk-stable] [PATCH] app/testpmd: fix Segment fault
> when start fwd
> 
> Hi ShougangX, Ferruh,
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ferruh Yigit
> > Sent: Monday, September 23, 2019 12:04 PM
> > To: Wang, ShougangX <shougangx.wang@intel.com>; dev@dpdk.org
> > Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Yang, Qiming
> > <qiming.yang@intel.com>; stable@dpdk.org
> > Subject: Re: [dpdk-dev] [dpdk-stable] [PATCH] app/testpmd: fix Segment
> > fault when start fwd
> >
> > On 9/17/2019 10:22 AM, Wang, ShougangX wrote:
> > >> Let's assume port already stopped before calling the reset, reset
> > >> will cause port to be started.
> > >
> > > Indeed, automatically start looks strange in this case. User
> > > explicitly do the "port start" command should be better.
> > >
> > >> I am for user explicitly do the stop, reset and start commands,
> > >> instead of reset automatically stop and start later.
> > >
> > > There are two reasons that it is necessary to stop automatically in
> > > "port
> > reset" command:
> > > 1) Even without this patch, user does not need to manually execute
> > > "port stop" command before "port reset" too,  because port will be
> > stopped in rte_eth_dev_reset() function.
> > > But this function does not update the port status flag of testpmd.
> > > It makes the port state recorded by testpmd inconsistent with the
> > > actual port state. So I add stop processing in
> > > reset_port() function to stop port as same as running "port stop"
> > command.
> >
> > I see 'rte_eth_dev_reset()' API calls the 'rte_eth_dev_stop()' but it
> > isn't enough as you said and a testpmd stop is required, instead of
> > doing in the function it is easy to detect port is not stopped and
> > return an error in the 'reset', it is up to user to stop and do the reset.
> >
> > >
> > > 2) If let user to stop port manually when he wants to reset port, it
> > > is not
> > easy to use than before.
> >
> > I still prefer 'Explicit is better than implicit.' [1], yes it is two
> > commands now to reset the port if it is already started but I don't see this is a
> problem.
> >
> > Anyway this is not a big deal, if testpmd maintainers are OK for it we
> > can continue with this...
> 
> I am inclined to agree with Ferruh, that it would be better to return an error if
> the port is not stopped when "port reset" is called rather that silently stopping
> the port.
> 

I will adopt your suggestion.

> 
> > [1] see: The Zen of Python :)
> >
> > >
> > > Thanks.
> > > Shougang
> > >
> > >
> > >> -----Original Message-----
> > >> From: Yigit, Ferruh
> > >> Sent: Monday, September 16, 2019 11:28 PM
> > >> To: Wang, ShougangX <shougangx.wang@intel.com>; dev@dpdk.org
> > >> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Yang, Qiming
> > >> <qiming.yang@intel.com>; stable@dpdk.org
> > >> Subject: Re: [dpdk-stable] [PATCH] app/testpmd: fix Segment fault
> > >> when start fwd
> > >>
> > >> On 9/16/2019 7:37 AM, Wang, ShougangX wrote:
> > >>> Hi Ferruh
> > >>>
> > >>> Thanks for your reply.
> > >>>
> > >>>> Not sure if 'reset' command should do more than it says, if there
> > >>>> is a requirement that port should be stopped, why not add this
> > >>>> condition with an error message so that user can stop the port in
> > advance if she wants.
> > >>>
> > >>> Firstly, port must be stopped before reset. Usually, port is
> > >>> stopped by rte_eth_dev_reset(), so testpmd does not prompt user to stop
> port.
> > >>> Although it can stop port, but testpmd does not change its own
> > >>> port status
> > >> flag to "RTE_PORT_STOPPED" and it will cause "port start" to fail.
> > >>> So I add this patch to stop port as same as running "port stop" command.
> > >>
> > >> Let's assume port already stopped before calling the reset, reset
> > >> will cause port to be started.
> > >> I am for user explicitly do the stop, reset and start commands,
> > >> instead of reset automatically stop and start later.
> > >>
> > >>>
> > >>>> - 'reset_port()' function has a loop inside, 'RTE_ETH_FOREACH_DEV()'
> > >>>> but it works on single port, the loop looked unnecessary to me,
> > >>>> can you please check and remove the loop if required?
> > >>>
> > >>> "port reset" supports reset all ports (testpmd > port reset all),
> > >>> so this loop is
> > >> necessary.
> > >>
> > >> Got it.
> > >>
> > >>>
> > >>>> - I am not able to see 'reset' has been documented in
> > >>>> 'doc/guides/testpmd_app_ug/testpmd_funcs.rst', it may be missing,
> > >>>> can you please check and add it if required?
> > >>>
> > >>> OK. I will add it in the next patch.
> > >>>
> > >>> Thanks.
> > >>> Shougang
> > >>>
> > >>>
> > >>>> -----Original Message-----
> > >>>> From: Yigit, Ferruh
> > >>>> Sent: Saturday, September 14, 2019 1:35 AM
> > >>>> To: Wang, ShougangX <shougangx.wang@intel.com>; dev@dpdk.org
> > >>>> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Yang, Qiming
> > >>>> <qiming.yang@intel.com>; stable@dpdk.org
> > >>>> Subject: Re: [dpdk-stable] [PATCH] app/testpmd: fix Segment fault
> > >>>> when start fwd
> > >>>>
> > >>>> On 9/6/2019 2:28 AM, Wang ShougangX wrote:
> > >>>>> This patch fixed the reset function to avoid crash when user
> > >>>>> don't call port reset , port stop and port start functions as sequence.
> > >>>>>
> > >>>>> Fixes: 97f1e19679 ("app/testpmd: add port reset command")
> > >>>>> Cc: stable@dpdk.org
> > >>>>>
> > >>>>> Signed-off-by: Wang ShougangX <shougangx.wang@intel.com>
> > >>>>> ---
> > >>>>>  app/test-pmd/testpmd.c | 6 ++++++
> > >>>>>  1 file changed, 6 insertions(+)
> > >>>>>
> > >>>>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
> > >>>>> index
> > >>>>> e8e2a39b6..273a7aa02 100644
> > >>>>> --- a/app/test-pmd/testpmd.c
> > >>>>> +++ b/app/test-pmd/testpmd.c
> > >>>>> @@ -2344,6 +2344,9 @@ reset_port(portid_t pid)
> > >>>>>  	if (port_id_is_invalid(pid, ENABLED_WARN))
> > >>>>>  		return;
> > >>>>>
> > >>>>> +	printf("Stopping ports...\n");
> > >>>>> +	stop_port(pid);
> > >>>>> +
> > >>>>>  	printf("Resetting ports...\n");
> > >>>>>
> > >>>>>  	RTE_ETH_FOREACH_DEV(pi) {
> > >>>>> @@ -2372,6 +2375,9 @@ reset_port(portid_t pid)
> > >>>>>  		}
> > >>>>>  	}
> > >>>>>
> > >>>>> +	printf("Starting ports...\n");
> > >>>>> +	start_port(pid);
> > >>>>> +
> > >>>>>  	printf("Done\n");
> > >>>>>  }
> > >>>>
> > >>>> Hi Shougang,
> > >>>>
> > >>>> Not sure if 'reset' command should do more than it says, if there
> > >>>> is a requirement that port should be stopped, why not add this
> > >>>> condition with an error message so that user can stop the port in
> > advance if she wants.
> > >>>>
> > >>>>
> > >>>> Btw, a few things related,
> > >>>> - 'reset_port()' function has a loop inside, 'RTE_ETH_FOREACH_DEV()'
> > >>>> but it works on single port, the loop looked unnecessary to me,
> > >>>> can you please check and remove the loop if required?
> > >>>>
> > >>>> - I am not able to see 'reset' has been documented in
> > >>>> 'doc/guides/testpmd_app_ug/testpmd_funcs.rst', it may be missing,
> > >>>> can you please check and add it if required?
> > >>>>
> > >>>> Thanks,
> > >>>> ferruh
> 
> Regards,
> 
> Bernard.
> 

Thanks.
Shougang