linux-kernel - Re: [PATCH] tick-sched: avoid a maybe-uninitialized warning

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Date:   Mon, 9 Apr 2018 19:53:30 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tick-sched: avoid a maybe-uninitialized warning

On Mon, Apr 9, 2018 at 6:18 PM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Arnd Bergmann <arnd@...db.de> wrote:
>
>> The use of bitfields seems to confuse gcc, leading to a false-positive
>> warning in all compiler versions:
>>
>> kernel/time/tick-sched.c: In function 'tick_nohz_idle_exit':
>> kernel/time/tick-sched.c:538:2: error: 'now' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>
>> This introduces a temporary variable to track the flags so gcc
>> doesn't have to evaluate twice, eliminating the code path that
>> leads to the warning.
>>
>> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85301
>> Fixes: 1cae544d42d2 ("nohz: Gather tick_sched booleans under a common flag field")
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>
> Which tree is this against? There's no such commit either in -tip, upstream or in
> -next AFAICS.

It's in today's linux-next. I found that it came in through Rafael's
pm/linux-next tree.

      Arnd