Re: [dpdk-dev] [PATCH 3/4] net/ice/base: fix build with gcc11

["Stillwell Jr, Paul M" <paul.m.stillwell.jr@intel.com>]

> -----Original Message-----
> From: Yigit, Ferruh <ferruh.yigit@intel.com>
> Sent: Monday, May 10, 2021 10:32 AM
> To: Wang, Haiyue <haiyue.wang@intel.com>; Yang, Qiming
> <qiming.yang@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>; Stillwell Jr, Paul
> M <paul.m.stillwell.jr@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>;
> Rong, Leyi <leyi.rong@intel.com>; Shukla, Shivanshu
> <shivanshu.shukla@intel.com>
> Cc: dev@dpdk.org; stable@dpdk.org; Kevin Traynor <ktraynor@redhat.com>;
> Ajit Khaparde <ajit.khaparde@broadcom.com>
> Subject: Re: [dpdk-dev] [PATCH 3/4] net/ice/base: fix build with gcc11
> 
> On 5/10/2021 6:13 PM, Wang, Haiyue wrote:
> >> -----Original Message-----
> >> From: Wang, Haiyue
> >> Sent: Tuesday, May 11, 2021 01:05
> >> To: Ferruh Yigit <ferruh.yigit@intel.com>; Yang, Qiming
> >> <qiming.yang@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>;
> >> Stillwell Jr, Paul M <paul.m.stillwell.jr@intel.com>; Lu, Wenzhuo
> >> <wenzhuo.lu@intel.com>; Rong, Leyi <leyi.rong@intel.com>; Shukla,
> >> Shivanshu <Shivanshu.Shukla@intel.com>
> >> Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; dev@dpdk.org;
> >> stable@dpdk.org; Kevin Traynor <ktraynor@redhat.com>; Ajit Khaparde
> >> <ajit.khaparde@broadcom.com>
> >> Subject: RE: [dpdk-dev] [PATCH 3/4] net/ice/base: fix build with
> >> gcc11
> >>
> >>> -----Original Message-----
> >>> From: dev <dev-bounces@dpdk.org> On Behalf Of Ferruh Yigit
> >>> Sent: Monday, May 10, 2021 23:03
> >>> To: Yang, Qiming <qiming.yang@intel.com>; Zhang, Qi Z
> >>> <qi.z.zhang@intel.com>; Stillwell Jr, Paul M
> >>> <paul.m.stillwell.jr@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>;
> >>> Rong, Leyi
> >> <leyi.rong@intel.com>;
> >>> Shukla, Shivanshu <shivanshu.shukla@intel.com>
> >>> Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; dev@dpdk.org;
> >>> stable@dpdk.org; Kevin Traynor <ktraynor@redhat.com>; Ajit Khaparde
> >>> <ajit.khaparde@broadcom.com>
> >>> Subject: [dpdk-dev] [PATCH 3/4] net/ice/base: fix build with gcc11
> >>>
> >>> Reproduced with '--buildtype=debugoptimized' config, compiler
> >>> version: gcc (GCC) 12.0.0 20210509 (experimental)
> >>>
> >>> There are multiple build errors, like:
> >>> ../drivers/net/ice/base/ice_switch.c: In function ‘ice_add_marker_act’:
> >>> ../drivers/net/ice/base/ice_switch.c:3727:15:
> >>>     warning: array subscript ‘struct ice_aqc_sw_rules_elem[0]’
> >>>     is partly outside array bounds of ‘unsigned char[52]’
> >>>     [-Warray-bounds]
> >>>  3727 |         lg_act->type = CPU_TO_LE16(ICE_AQC_SW_RULES_T_LG_ACT);
> >>>       |               ^~
> >>> In file included from ../drivers/net/ice/base/ice_type.h:52,
> >>>                  from ../drivers/net/ice/base/ice_common.h:8,
> >>>                  from ../drivers/net/ice/base/ice_switch.h:8,
> >>>                  from ../drivers/net/ice/base/ice_switch.c:5:
> >>> ../drivers/net/ice/base/ice_osdep.h:209:29:
> >>>     note: referencing an object of size 52 allocated by ‘rte_zmalloc’
> >>>   209 | #define ice_malloc(h, s)    rte_zmalloc(NULL, s, 0)
> >>>       |                             ^~~~~~~~~~~~~~~~~~~~~~~
> >>> ../drivers/net/ice/base/ice_switch.c:3720:50:
> >>>     note: in expansion of macro ‘ice_malloc’
> >>>   lg_act = (struct ice_aqc_sw_rules_elem *)ice_malloc(hw,
> >>> rules_size);
> >>>
> >>> These errors are mainly because allocated memory is cast to "struct
> >>> ice_aqc_sw_rules_elem *" but allocated size is less than the size of
> >>> "struct ice_aqc_sw_rules_elem".
> >>>
> >>> "struct ice_aqc_sw_rules_elem" has multiple other structs has
> >>> unions, based on which one is used allocated memory being less than
> >>> the size of "struct ice_aqc_sw_rules_elem" is logically correct but
> >>> compiler is complaining about it.
> >>>
> >>> As a solution making sure allocated memory size is at least size of
> >>> "struct ice_aqc_sw_rules_elem".
> >>> The function to use the struct is 'ice_aq_sw_rules()', and it
> >>> already has parameter for size of the rule, allocating more than
> >>> needed shouldn't cause any problem.
> >>>
> >>> Fixes: c7dd15931183 ("net/ice/base: add virtual switch code")
> >>> Fixes: 02acdce2f553 ("net/ice/base: add MAC filter with marker and
> >>> counter")
> >>> Fixes: f89aa3affa9e ("net/ice/base: support removing advanced rule")
> >>> Cc: stable@dpdk.org
> >>>
> >>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> >>> ---
> >>> Cc: paul.m.stillwell.jr@intel.com
> >>> Cc: qi.z.zhang@intel.com
> >>> Cc: leyi.rong@intel.com
> >>> Cc: Kevin Traynor <ktraynor@redhat.com>
> >>> Cc: Ajit Khaparde <ajit.khaparde@broadcom.com>
> >>> ---
> >>>  drivers/net/ice/base/ice_switch.c | 30
> >>> +++++++++++++++++++++++-------
> >>>  1 file changed, 23 insertions(+), 7 deletions(-)
> >>
> >> GCC bug ?
> >>
> >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98266
> >>
> >> Bug 98266 - [11 Regression] bogus array subscript is partly outside
> >> array bounds on virtual inheritance
> >>
> >
> > Disable this gcc warning ?  ;-)
> >
> 
> That is an option as well but I prefer to fix it warning as much as possible (unless
> false positive warnings).
> 
> What do you think about the patch? Do you see any problem with it?
> 

The correct way to handle this is to submit a patch to our internal shared code repo where the patch will get reviewed and merged. Once it is merged, then it can go upstream in DPDK.

Paul

> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/com
> > mit/?id=44720996e2d79e47d508b0abe99b931a726a3197
> >
> > gcc-10: disable 'array-bounds' warning for now
> >
> >>
> >>
> >>> --
> >>> 2.31.1
> >