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Subject: Re: [PATCH] s390: allow reschedule on syscall restart
To:     Sven Schnelle <svens@linux.ibm.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Cc:     Linux Next Mailing List <linux-next@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Frederic Weisbecker <frederic@kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>
References: <20210121143926.21440-1-svens@linux.ibm.com>
 <20210121143926.21440-2-svens@linux.ibm.com>
From:   Christian Borntraeger <borntraeger@de.ibm.com>
Message-ID: <a522c1ac-703a-ba99-c44c-3dd09e4cc4be@de.ibm.com>
Date:   Tue, 26 Jan 2021 07:59:51 +0100
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On 21.01.21 15:39, Sven Schnelle wrote:
> Commit 845f44e8ef28 ("sched: Report local wake up on resched blind zone
> within idle loop") from next-20210121 causes a warning because s390
> doesn't call sched_resched_local_allow() when restarting a syscall.
> 
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
> ---
>  arch/s390/kernel/syscall.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/kernel/syscall.c b/arch/s390/kernel/syscall.c
> index bc8e650e377d..2b39ac40f970 100644
> --- a/arch/s390/kernel/syscall.c
> +++ b/arch/s390/kernel/syscall.c
> @@ -162,6 +162,7 @@ void noinstr __do_syscall(struct pt_regs *regs, int per_trap)
>  		do_syscall(regs);
>  		if (!test_pt_regs_flag(regs, PIF_SYSCALL_RESTART))
>  			break;
> +		sched_resched_local_allow();
>  		local_irq_enable();
>  	}
>  	exit_to_user_mode();

Yesterdays next now fails with


arch/s390/kernel/syscall.c: In function '__do_syscall':
arch/s390/kernel/syscall.c:165:3: error: implicit declaration of function 'sched_resched_local_allow' [-Werror=implicit-function-declaration]
  165 |   sched_resched_local_allow();
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:288: arch/s390/kernel/syscall.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [scripts/Makefile.build:530: arch/s390/kernel] Error 2
make[1]: *** Waiting for unfinished jobs....