Re: [dpdk-dev] [dpdk-ci] [EXT] [PATCH 0/8] DSW performance and statistics improvements

[Thomas Monjalon <thomas@monjalon.net>]

15/04/2020 19:39, Mattias Rönnblom:
> On 2020-04-15 18:37, David Marchand wrote:
> > On Sat, Apr 4, 2020 at 4:35 PM Jerin Jacob Kollanukkaran
> > <jerinj@marvell.com> wrote:
> >> From: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
> >>> Performance and statistics improvements for the distributed software
> >>> (DSW) event device.
> >>>
> >>> Mattias Rönnblom (8):
> >>>    event/dsw: reduce latency in low-load situations
> >>>    event/dsw: reduce max flows to speed up load balancing
> >>>    event/dsw: extend statistics
> >>>    event/dsw: improve migration mechanism
> >>>    event/dsw: avoid migration waves in large systems
> >>>    event/dsw: remove redundant control ring poll
> >>>    event/dsw: remove unnecessary read barrier
> >>>    event/dsw: add port busy cycles xstats
> >> Series applied to dpdk-next-eventdev/master. Thanks.
> > 
> > I get a compilation issue on rhel7.
> > Too bad the CI did not help.
> > https://protect2.fireeye.com/v1/url?k=6777ccba-3ba3c0e4-67778c21-8691959ed9b7-56149d0a5dee8fea&q=1&e=d034618d-5861-42ba-adf3-fc0aafd4892a&u=http%3A%2F%2Fpatchwork.dpdk.org%2Fproject%2Fdpdk%2Flist%2F%3Fseries%3D8828%26state%3D%2A
> >
> >
> > [1583/1808] Compiling C object
> > 'drivers/drivers@@tmp_rte_pmd_dsw_event@sta/event_dsw_dsw_event.c.o'.
> > ../drivers/event/dsw/dsw_event.c: In function ‘dsw_port_consider_emigration’:
> > ../drivers/event/dsw/dsw_event.c:502:27: warning: ‘candidate_qf’ may
> > be used uninitialized in this function [-Wmaybe-uninitialized]
> >    target_qfs[*targets_len] = *candidate_qf;
> >                             ^
> > ../drivers/event/dsw/dsw_event.c:445:25: note: ‘candidate_qf’ was declared here
> >    struct dsw_queue_flow *candidate_qf;
> >                           ^
> > In file included from ../lib/librte_eal/x86/include/rte_atomic.h:16:0,
> >                   from ../lib/librte_eal/include/generic/rte_rwlock.h:25,
> >                   from ../lib/librte_eal/x86/include/rte_rwlock.h:12,
> >                   from ../lib/librte_eal/include/rte_fbarray.h:40,
> >                   from ../lib/librte_eal/include/rte_memory.h:25,
> >                   from ../lib/librte_eventdev/rte_event_ring.h:20,
> >                   from ../drivers/event/dsw/dsw_evdev.h:8,
> >                   from ../drivers/event/dsw/dsw_event.c:5:
> > ../lib/librte_eal/include/generic/rte_atomic.h:566:22: warning:
> > ‘candidate_flow_load’ may be used uninitialized in this function
> > [-Wmaybe-uninitialized]
> >    __sync_fetch_and_add(&v->cnt, inc);
> >                        ^
> > ../drivers/event/dsw/dsw_event.c:448:10: note: ‘candidate_flow_load’
> > was declared here
> >    int16_t candidate_flow_load;
> >            ^
> > ../drivers/event/dsw/dsw_event.c:505:49: warning: ‘candidate_port_id’
> > may be used uninitialized in this function [-Wmaybe-uninitialized]
> >    rte_atomic32_add(&dsw->ports[candidate_port_id].immigration_load,
> >                                                   ^
> > ../drivers/event/dsw/dsw_event.c:446:10: note: ‘candidate_port_id’ was
> > declared here
> >    uint8_t candidate_port_id;
> >            ^
> >
> 
> Looks like a false positive. What GCC version is this?

This is with RHEL 7.
Please do you have such distro to test and fix the false positive?
A quick fix would be very welcome.