linux-kernel - Re: [PATCH] s390: allow reschedule on syscall restart

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Date:   Tue, 26 Jan 2021 10:39:11 +0100
From:   Sven Schnelle <svens@...ux.ibm.com>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Frederic Weisbecker <frederic@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH] s390: allow reschedule on syscall restart

Christian Borntraeger <borntraeger@...ibm.com> writes:

> 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@...ux.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....

Looks to me like 845f44e8ef28 ("sched: Report local wake up on resched
blind zone") was removed from linux-next. Stephen, can you remove my
commit as well? It is no longer needed.

Thanks
Sven