[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <Y2UOQpniaV12E0P9@hirez.programming.kicks-ass.net>
Date: Fri, 4 Nov 2022 14:06:10 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Florian Fainelli <f.fainelli@...il.com>
Cc: linux-kernel@...r.kernel.org, anand.gore@...adcom.com,
william.zhang@...adcom.com, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Anna-Maria Gleixner <anna-maria@...utronix.de>,
Sebastian Siewior <bigeasy@...utronix.de>,
Thomas Gleixner <tglx@...utronix.de>,
"open list:PERFORMANCE EVENTS SUBSYSTEM"
<linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH] perf: Fix perf_event_{init,exit}_cpu stubs
On Thu, Nov 03, 2022 at 03:43:03PM -0700, Florian Fainelli wrote:
> The original commit that introduced those stubs was already at fault,
> but in the absence of a caller of perf_event_{init,exit}_cpu outside of
> code that is compiled regardless of CONFIG_PERF_EVENTS, the build
> failure cannot be observed. This was observed with the Android kernel to
> produce a build failure similar to this:
>
> In file included from ./include/uapi/linux/posix_types.h:5,
> from ./include/uapi/linux/types.h:14,
> from ./include/linux/types.h:6,
> from ./include/linux/limits.h:6,
> from ./include/linux/kernel.h:7,
> from ./include/linux/sched/mm.h:5,
> from kernel/cpu.c:6:
> kernel/cpu.c: In function 'random_and_perf_prepare_fusion':
> ./include/linux/stddef.h:8:14: error: called object is not a function or function pointer
> #define NULL ((void *)0)
> ^
> ./include/linux/perf_event.h:1607:29: note: in expansion of macro 'NULL'
> #define perf_event_init_cpu NULL
> ^~~~
> kernel/cpu.c:1686:2: note: in expansion of macro 'perf_event_init_cpu'
> perf_event_init_cpu(cpu);
> ^~~~~~~~~~~~~~~~~~~
What is the actual problem reported here? Did you see all the other NULL
assignments in cpuhp_hp_states ?
>
> Fixes: 00e16c3d68fc ("perf/core: Convert to hotplug state machine")
> Reported-by: Anand Gore <anand.gore@...adcom.com>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
> include/linux/perf_event.h | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 0031f7b4d9ab..592040e2398c 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -1678,8 +1678,15 @@ static struct device_attribute format_attr_##_name = __ATTR_RO(_name)
> int perf_event_init_cpu(unsigned int cpu);
> int perf_event_exit_cpu(unsigned int cpu);
> #else
> -#define perf_event_init_cpu NULL
> -#define perf_event_exit_cpu NULL
> +static inline int perf_event_init_cpu(unsigned int cpu)
> +{
> + return 0;
> +}
> +
> +static inline int perf_event_exit_cpu(unsigned int cpu)
> +{
> + return 0;
> +}
> #endif
>
> extern void __weak arch_perf_update_userpage(struct perf_event *event,
> --
> 2.25.1
>
Powered by blists - more mailing lists