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Message-ID: <20210515165647.GJ1922@kadam>
Date: Sat, 15 May 2021 19:56:47 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: Ido Schimmel <idosch@...dia.com>
Cc: kbuild@...ts.01.org, lkp@...el.com, kbuild-all@...ts.01.org,
linux-kernel@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
Jiri Pirko <jiri@...dia.com>
Subject: Re: drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:3598
mlxsw_sp_nexthop_group_refresh() warn: missing error code 'err'
On Sat, May 15, 2021 at 07:53:43PM +0300, Dan Carpenter wrote:
> On Sat, May 15, 2021 at 06:48:40PM +0300, Ido Schimmel wrote:
> > On Fri, May 14, 2021 at 05:35:00PM +0300, Dan Carpenter wrote:
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head: 315d99318179b9cd5077ccc9f7f26a164c9fa998
> > > commit: e3ddfb45bacdc623eedea7f7bf9e7879257471d6 mlxsw: spectrum_router: Allow returning errors from mlxsw_sp_nexthop_group_refresh()
> > > config: x86_64-randconfig-m031-20210514 (attached as .config)
> > > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@...el.com>
> > > Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> > >
> > > smatch warnings:
> > > drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:3598 mlxsw_sp_nexthop_group_refresh() warn: missing error code 'err'
> > >
> > > vim +/err +3598 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> > >
> > > e3ddfb45bacdc6 Ido Schimmel 2020-11-17 3555 static int
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3556 mlxsw_sp_nexthop_group_refresh(struct mlxsw_sp *mlxsw_sp,
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3557 struct mlxsw_sp_nexthop_group *nh_grp)
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3558 {
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3559 struct mlxsw_sp_nexthop_group_info *nhgi = nh_grp->nhgi;
> > > eb789980d0aa6c Ido Schimmel 2017-10-22 3560 u16 ecmp_size, old_ecmp_size;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3561 struct mlxsw_sp_nexthop *nh;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3562 bool offload_change = false;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3563 u32 adj_index;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3564 bool old_adj_index_valid;
> > > e3ddfb45bacdc6 Ido Schimmel 2020-11-17 3565 int i, err2, err = 0;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3566 u32 old_adj_index;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3567
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3568 if (!nhgi->gateway) {
> > > b3e8d1ebad2d04 Ido Schimmel 2017-02-08 3569 mlxsw_sp_nexthop_fib_entries_update(mlxsw_sp, nh_grp);
> > > e3ddfb45bacdc6 Ido Schimmel 2020-11-17 3570 return 0;
> > > b3e8d1ebad2d04 Ido Schimmel 2017-02-08 3571 }
> > > b3e8d1ebad2d04 Ido Schimmel 2017-02-08 3572
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3573 for (i = 0; i < nhgi->count; i++) {
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3574 nh = &nhgi->nexthops[i];
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3575
> > > 56b8a9ed276bc1 Petr Machata 2017-07-31 3576 if (nh->should_offload != nh->offloaded) {
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3577 offload_change = true;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3578 if (nh->should_offload)
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3579 nh->update = 1;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3580 }
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3581 }
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3582 if (!offload_change) {
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3583 /* Nothing was added or removed, so no need to reallocate. Just
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3584 * update MAC on existing adjacency indexes.
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3585 */
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3586 err = mlxsw_sp_nexthop_group_update(mlxsw_sp, nhgi, false);
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3587 if (err) {
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3588 dev_warn(mlxsw_sp->bus_info->dev, "Failed to update neigh MAC in adjacency table.\n");
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3589 goto set_trap;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3590 }
> > > e3ddfb45bacdc6 Ido Schimmel 2020-11-17 3591 return 0;
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3592 }
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3593 mlxsw_sp_nexthop_group_normalize(nhgi);
> > > 7f7a417e6a11d7 Ido Schimmel 2020-11-13 3594 if (!nhgi->sum_norm_weight)
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3595 /* No neigh of this group is connected so we just set
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3596 * the trap and let everthing flow through kernel.
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 3597 */
> > > a7ff87acd995e3 Jiri Pirko 2016-07-05 @3598 goto set_trap;
> > >
> > > The comments sort of imply that this is a success path so no error
> > > code necessary. It's sort of hard to be positive though...
> >
> > Thanks for the report, Dan. This is indeed a success path. How do you
> > suggest to handle it in order to avoid the warning on future smatch
> > invocations? I regularly run smatch before submitting patches and I
> > would like to keep it error/warning free.
> >
>
> You could move setting the error to within 4 lines of the goto:
>
> err = 0;
> goto set_trap;
>
> This check basically assumes that if you have a cleanup block after
> a return 0; then it should return a negative error code. It finds
> quite a few bugs and I'm generally happy with it. But like this is
> open source and all so I'm also always open to different ideas if you
> have a way to improve the check.
Actually, duh, I could make it a rule that if there is a comment like
this before the goto then it's probably fine.
This is quite tricky to implement in Smatch because Smatch works on the
preprocessed code so I can't promise that I will implement that change
right away.
regards,
dan carpenter
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