Re: [kbuild-all] Re: [linux-next:master 4040/7019] arch/powerpc/kernel/interrupt.c:542:55: error: suggest braces around empty body in an 'if' statement

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From: "Chen, Rong A" <rong.a.chen@intel.com>
To: paulmck@kernel.org, kernel test robot <lkp@intel.com>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	kbuild-all@lists.01.org,
	Linux Memory Management List <linux-mm@kvack.org>,
	Nicolas Saenz Julienne <nsaenzju@redhat.com>
Subject: Re: [kbuild-all] Re: [linux-next:master 4040/7019] arch/powerpc/kernel/interrupt.c:542:55: error: suggest braces around empty body in an 'if' statement
Date: Fri, 1 Jul 2022 18:11:31 +0800	[thread overview]
Message-ID: <1fc26d59-e5b9-cde3-7af2-d889d3fed7f9@intel.com> (raw)
In-Reply-To: <20220630210115.GY1790663@paulmck-ThinkPad-P17-Gen-1>



On 7/1/2022 5:01 AM, Paul E. McKenney wrote:
> On Fri, Jul 01, 2022 at 02:23:30AM +0800, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
>> head:   6cc11d2a1759275b856e464265823d94aabd5eaf
>> commit: 408c74a2d8f01262e152b7eb09500033fbe6bafe [4040/7019] context_tracking: Convert state to atomic_t
>> config: powerpc-amigaone_defconfig (https://download.01.org/0day-ci/archive/20220701/202207010213.PDJ0d9Vj-lkp@intel.com/config)
>> compiler: powerpc-linux-gcc (GCC) 11.3.0
>> reproduce (this is a W=1 build):
>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>          chmod +x ~/bin/make.cross
>>          # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=408c74a2d8f01262e152b7eb09500033fbe6bafe
>>          git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
>>          git fetch --no-tags linux-next master
>>          git checkout 408c74a2d8f01262e152b7eb09500033fbe6bafe
>>          # save the config file
>>          mkdir build_dir && cp config build_dir/.config
>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash
>>
>> If you fix the issue, kindly add following tag where applicable
>> Reported-by: kernel test robot <lkp@intel.com>
> 
> Good catch!  Does the updated commit 344e00943785 ("context_tracking:
> Convert state to atomic_t") address this issue?
> 
> 							Thanx, Paul

Hi Paul,

Yes, I have confirmed that there's no such issue on commit 344e00943785.

Best Regards,
Rong Chen

> 
>> All errors (new ones prefixed by >>):
>>
>>     arch/powerpc/kernel/interrupt.c: In function 'interrupt_exit_kernel_prepare':
>>>> arch/powerpc/kernel/interrupt.c:542:55: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
>>       542 |                 CT_WARN_ON(ct_state() == CONTEXT_USER);
>>           |                                                       ^
>>     cc1: all warnings being treated as errors
>>
>>
>> vim +/if +542 arch/powerpc/kernel/interrupt.c
>>
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  527
>> bf9155f1970c4d arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  528  notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs)
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  529  {
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  530  	unsigned long flags;
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  531  	unsigned long ret = 0;
>> ad2d2344771dab arch/powerpc/kernel/interrupt.c  Christophe Leroy 2021-03-12  532  	unsigned long kuap;
>> 985faa78687de6 arch/powerpc/kernel/interrupt.c  Mark Rutland     2021-11-29  533  	bool stack_store = read_thread_flags() & _TIF_EMULATE_STACK_STORE;
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  534
>> 806c0e6e7e97ad arch/powerpc/kernel/interrupt.c  Christophe Leroy 2021-08-23  535  	if (regs_is_unrecoverable(regs))
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  536  		unrecoverable_exception(regs);
>> f821bc97dee4f3 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2021-01-30  537  	/*
>> f821bc97dee4f3 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2021-01-30  538  	 * CT_WARN_ON comes here via program_check_exception,
>> f821bc97dee4f3 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2021-01-30  539  	 * so avoid recursion.
>> f821bc97dee4f3 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2021-01-30  540  	 */
>> 7153d4bf0b3734 arch/powerpc/kernel/interrupt.c  Xiongwei Song    2021-04-14  541  	if (TRAP(regs) != INTERRUPT_PROGRAM)
>> f821bc97dee4f3 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2021-01-30 @542  		CT_WARN_ON(ct_state() == CONTEXT_USER);
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  543
>> ad2d2344771dab arch/powerpc/kernel/interrupt.c  Christophe Leroy 2021-03-12  544  	kuap = kuap_get_and_assert_locked();
>> c0d7dcf89e5151 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-04-29  545
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  546  	local_irq_save(flags);
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  547
>> 344bb20b159dd0 arch/powerpc/kernel/interrupt.c  Christophe Leroy 2021-02-08  548  	if (!arch_irq_disabled_regs(regs)) {
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  549  		/* Returning to a kernel context with local irqs enabled. */
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  550  		WARN_ON_ONCE(!(regs->msr & MSR_EE));
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  551  again:
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  552  		if (IS_ENABLED(CONFIG_PREEMPT)) {
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  553  			/* Return to preemptible kernel context */
>> 985faa78687de6 arch/powerpc/kernel/interrupt.c  Mark Rutland     2021-11-29  554  			if (unlikely(read_thread_flags() & _TIF_NEED_RESCHED)) {
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  555  				if (preempt_count() == 0)
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  556  					preempt_schedule_irq();
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  557  			}
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  558  		}
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  559
>> 6eaaf9de359986 arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-22  560  		check_return_regs_valid(regs);
>> 6eaaf9de359986 arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-22  561
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  562  		/*
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  563  		 * Stack store exit can't be restarted because the interrupt
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  564  		 * stack frame might have been clobbered.
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  565  		 */
>> 61eece2d170779 arch/powerpc/kernel/interrupt.c  Christophe Leroy 2021-06-18  566  		if (!prep_irq_for_enabled_exit(unlikely(stack_store))) {
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  567  			/*
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  568  			 * Replay pending soft-masked interrupts now. Don't
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  569  			 * just local_irq_enabe(); local_irq_disable(); because
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  570  			 * if we are returning from an asynchronous interrupt
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  571  			 * here, another one might hit after irqs are enabled,
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  572  			 * and it would exit via this same path allowing
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  573  			 * another to fire, and so on unbounded.
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  574  			 */
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  575  			hard_irq_disable();
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  576  			replay_soft_interrupts();
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  577  			/* Took an interrupt, may have more exit work to do. */
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  578  			goto again;
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  579  		}
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  580  #ifdef CONFIG_PPC64
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  581  		/*
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  582  		 * An interrupt may clear MSR[EE] and set this concurrently,
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  583  		 * but it will be marked pending and the exit will be retried.
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  584  		 * This leaves a racy window where MSR[EE]=0 and HARD_DIS is
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  585  		 * clear, until interrupt_exit_kernel_restart() calls
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  586  		 * hard_irq_disable(), which will set HARD_DIS again.
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  587  		 */
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  588  		local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  589
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  590  	} else {
>> 6eaaf9de359986 arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-22  591  		check_return_regs_valid(regs);
>> 6eaaf9de359986 arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-22  592
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  593  		if (unlikely(stack_store))
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  594  			__hard_EE_RI_disable();
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  595  		/*
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  596  		 * Returning to a kernel context with local irqs disabled.
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  597  		 * Here, if EE was enabled in the interrupted context, enable
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  598  		 * it on return as well. A problem exists here where a soft
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  599  		 * masked interrupt may have cleared MSR[EE] and set HARD_DIS
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  600  		 * here, and it will still exist on return to the caller. This
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  601  		 * will be resolved by the masked interrupt firing again.
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  602  		 */
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  603  		if (regs->msr & MSR_EE)
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  604  			local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  605  #endif /* CONFIG_PPC64 */
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  606  	}
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  607
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  608  	if (unlikely(stack_store)) {
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  609  		clear_bits(_TIF_EMULATE_STACK_STORE, &current_thread_info()->flags);
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  610  		ret = 1;
>> 13799748b957bc arch/powerpc/kernel/interrupt.c  Nicholas Piggin  2021-06-18  611  	}
>> 6cc0c16d82f889 arch/powerpc/kernel/syscall_64.c Nicholas Piggin  2020-02-26  612
>>
>> :::::: The code at line 542 was first introduced by commit
>> :::::: f821bc97dee4f3ee92c3668d495af49dfd720fe0 powerpc/64s: move context tracking exit to interrupt exit path
>>
>> :::::: TO: Nicholas Piggin <npiggin@gmail.com>
>> :::::: CC: Michael Ellerman <mpe@ellerman.id.au>
>>
>> -- 
>> 0-DAY CI Kernel Test Service
>> https://01.org/lkp
> _______________________________________________
> kbuild-all mailing list -- kbuild-all@lists.01.org
> To unsubscribe send an email to kbuild-all-leave@lists.01.org
>

next prev parent reply	other threads:[~2022-07-01 10:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-30 18:23 kernel test robot
2022-06-30 21:01 ` Paul E. McKenney
2022-07-01 10:11   ` Chen, Rong A [this message]
2022-07-01 13:51     ` [kbuild-all] " Paul E. McKenney

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