From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FD9FEB64DD for ; Fri, 21 Jul 2023 16:27:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232128AbjGUQ1d (ORCPT ); Fri, 21 Jul 2023 12:27:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232725AbjGUQ1O (ORCPT ); Fri, 21 Jul 2023 12:27:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC3B04C2F for ; Fri, 21 Jul 2023 09:24:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6D98261D4C for ; Fri, 21 Jul 2023 16:23:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8382FC433C9; Fri, 21 Jul 2023 16:23:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689956623; bh=PdWqhmPU64/bDJgg3cIcNQdYvKW41b039MZObuoWUhw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V51oU653vri8fCcPEQ2NCnwEPVX+V0hLPEsGoyVF8oFo6f3k9oG1tcaNA2jo2saEy c7Yt+gJVZtC+YFi3tEIuDegINOuKuZujWijvvq7VDOVbLwEYLpLYAUZfXg3fOFSTT5 xZVoLThEkdudyf0ZeDlRsDfeHdGsFRhAiqN1B0Jg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Lin , Palmer Dabbelt Subject: [PATCH 6.4 241/292] perf: RISC-V: Remove PERF_HES_STOPPED flag checking in riscv_pmu_start() Date: Fri, 21 Jul 2023 18:05:50 +0200 Message-ID: <20230721160539.245586744@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160528.800311148@linuxfoundation.org> References: <20230721160528.800311148@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Lin commit 66843b14fb71825fdd73ab12f6594f2243b402be upstream. Since commit 096b52fd2bb4 ("perf: RISC-V: throttle perf events") the perf_sample_event_took() function was added to report time spent in overflow interrupts. If the interrupt takes too long, the perf framework will lower the sysctl_perf_event_sample_rate and max_samples_per_tick. When hwc->interrupts is larger than max_samples_per_tick, the hwc->interrupts will be set to MAX_INTERRUPTS, and events will be throttled within the __perf_event_account_interrupt() function. However, the RISC-V PMU driver doesn't call riscv_pmu_stop() to update the PERF_HES_STOPPED flag after perf_event_overflow() in pmu_sbi_ovf_handler() function to avoid throttling. When the perf framework unthrottled the event in the timer interrupt handler, it triggers riscv_pmu_start() function and causes a WARN_ON_ONCE() warning, as shown below: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 240 at drivers/perf/riscv_pmu.c:184 riscv_pmu_start+0x7c/0x8e Modules linked in: CPU: 0 PID: 240 Comm: ls Not tainted 6.4-rc4-g19d0788e9ef2 #1 Hardware name: SiFive (DT) epc : riscv_pmu_start+0x7c/0x8e ra : riscv_pmu_start+0x28/0x8e epc : ffffffff80aef864 ra : ffffffff80aef810 sp : ffff8f80004db6f0 gp : ffffffff81c83750 tp : ffffaf80069f9bc0 t0 : ffff8f80004db6c0 t1 : 0000000000000000 t2 : 000000000000001f s0 : ffff8f80004db720 s1 : ffffaf8008ca1068 a0 : 0000ffffffffffff a1 : 0000000000000000 a2 : 0000000000000001 a3 : 0000000000000870 a4 : 0000000000000000 a5 : 0000000000000000 a6 : 0000000000000840 a7 : 0000000000000030 s2 : 0000000000000000 s3 : ffffaf8005165800 s4 : ffffaf800424da00 s5 : ffffffffffffffff s6 : ffffffff81cc7590 s7 : 0000000000000000 s8 : 0000000000000006 s9 : 0000000000000001 s10: ffffaf807efbc340 s11: ffffaf807efbbf00 t3 : ffffaf8006a16028 t4 : 00000000dbfbb796 t5 : 0000000700000000 t6 : ffffaf8005269870 status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003 [] riscv_pmu_start+0x7c/0x8e [] perf_adjust_freq_unthr_context+0x15e/0x174 [] perf_event_task_tick+0x88/0x9c [] scheduler_tick+0xfe/0x27c [] update_process_times+0x9a/0xba [] tick_sched_handle+0x32/0x66 [] tick_sched_timer+0x64/0xb0 [] __hrtimer_run_queues+0x156/0x2f4 [] hrtimer_interrupt+0xe2/0x1fe [] riscv_timer_interrupt+0x38/0x42 [] handle_percpu_devid_irq+0x90/0x1d2 [] generic_handle_domain_irq+0x28/0x36 After referring other PMU drivers like Arm, Loongarch, Csky, and Mips, they don't call *_pmu_stop() to update with PERF_HES_STOPPED flag after perf_event_overflow() function nor do they add PERF_HES_STOPPED flag checking in *_pmu_start() which don't cause this warning. Thus, it's recommended to remove this unnecessary check in riscv_pmu_start() function to prevent this warning. Signed-off-by: Eric Lin Link: https://lore.kernel.org/r/20230710154328.19574-1-eric.lin@sifive.com Fixes: 096b52fd2bb4 ("perf: RISC-V: throttle perf events") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- drivers/perf/riscv_pmu.c | 3 --- 1 file changed, 3 deletions(-) --- a/drivers/perf/riscv_pmu.c +++ b/drivers/perf/riscv_pmu.c @@ -181,9 +181,6 @@ void riscv_pmu_start(struct perf_event * uint64_t max_period = riscv_pmu_ctr_get_width_mask(event); u64 init_val; - if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED))) - return; - if (flags & PERF_EF_RELOAD) WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));