From: "Paul E. McKenney" <paulmck@kernel.org>
To: 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: [linux-next:master 4040/7019] arch/powerpc/kernel/interrupt.c:542:55: error: suggest braces around empty body in an 'if' statement
Date: Thu, 30 Jun 2022 14:01:15 -0700 [thread overview]
Message-ID: <20220630210115.GY1790663@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <202207010213.PDJ0d9Vj-lkp@intel.com>
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
> 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, ¤t_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
next prev parent reply other threads:[~2022-06-30 21:01 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 [this message]
2022-07-01 10:11 ` [kbuild-all] " Chen, Rong A
2022-07-01 13:51 ` Paul E. McKenney
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