From mboxrd@z Thu Jan  1 00:00:00 1970
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From: Liang, Kan <kan.liang@linux.intel.com>
To: kbuild-all@lists.01.org
Subject: Re: [peterz-queue:perf/core 26/39] arch/x86/include/asm/perf_event.h:290:19: error: flexible array member in a struct with no named members
Date: Mon, 06 Jul 2020 21:08:41 -0400
Message-ID: <0f880910-7082-ecbb-11ba-1b0d05fd49db@linux.intel.com>
In-Reply-To: <202007070345.ILUNskpS%lkp@intel.com>
List-Id: <oe-kbuild-all.lists.linux.dev>

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>>> arch/x86/include/asm/perf_event.h:290:19: error: flexible array member =
in a struct with no named members
>       290 |  struct lbr_entry lbr[]; /* Variable length */
>           |                   ^~~
>     kernel/sched/rt.c:253:6: warning: no previous prototype for 'free_rt_=
sched_group' [-Wmissing-prototypes]
>       253 | void free_rt_sched_group(struct task_group *tg) { }
>           |      ^~~~~~~~~~~~~~~~~~~
>     kernel/sched/rt.c:255:5: warning: no previous prototype for 'alloc_rt=
_sched_group' [-Wmissing-prototypes]
>       255 | int alloc_rt_sched_group(struct task_group *tg, struct task_g=
roup *parent)
>           |     ^~~~~~~~~~~~~~~~~~~~
>     kernel/sched/rt.c:668:6: warning: no previous prototype for 'sched_rt=
_bandwidth_account' [-Wmissing-prototypes]
>       668 | bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
>           |      ^~~~~~~~~~~~~~~~~~~~~~~~~~
> =

> vim +290 arch/x86/include/asm/perf_event.h
> =

>     288	=

>     289	struct pebs_lbr {
>   > 290		struct lbr_entry lbr[]; /* Variable length */
>     291	};
>     292	=

>

The struct pebs_lbr only has one member. To fix the warning, it seems we =

have to define the struct as below.


diff --git a/arch/x86/include/asm/perf_event.h =

b/arch/x86/include/asm/perf_event.h
index 2338200..a387e14 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -283,7 +283,7 @@ struct pebs_xmm {
  };

  struct pebs_lbr {
-	struct lbr_entry lbr[]; /* Variable length */
+	struct lbr_entry lbr[0]; /* Variable length */
  };


Thanks,
Kan
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