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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9BA2DCA0EFA for ; Tue, 26 Aug 2025 11:49:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WdcZGco1brKkCvqK3OI1tB4ut3wEQd56prbkyXuFUMU=; b=GJwyHFCGAQ4wnVa2JWD5UjBiQ/ IKLJqtBGZpSXpZgBX+NOxB3pIaS8ZwukPR8/FkCyxXGipsVn2ZztJYE/GXKs0CFwPrKygqBPM3de8 BlP0qWGL3OJ0yUWaVUjn4w+C8oLHJu6FNuC7iYPWOA3QAB2ogkvgzauuica7rg6qXSLQU+vi03gGo mvF+kRfRhYIpmD1Yr41rWPrnt48n7iB6LY6MF8/DzLFVXt9fD+Ox4cRudwPCi7l3OKZKv590f40Sh dwFCWJif+NeC/qf638af7q14TzILE1VECsEWUMnIcMY2mV98PPomCi0w+worr/gwtueUw4rC6n/hF gDgYT9cQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqsBA-0000000BquX-0Rxg; Tue, 26 Aug 2025 11:49:32 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqreP-0000000BkGg-1ml9; Tue, 26 Aug 2025 11:15:43 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0E7AF1A00; Tue, 26 Aug 2025 04:15:32 -0700 (PDT) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 663C13F63F; Tue, 26 Aug 2025 04:15:28 -0700 (PDT) Date: Tue, 26 Aug 2025 12:15:23 +0100 From: Mark Rutland To: Robin Murphy Cc: peterz@infradead.org, mingo@redhat.com, will@kernel.org, acme@kernel.org, namhyung@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, linux-csky@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-pm@vger.kernel.org, linux-rockchip@lists.infradead.org, dmaengine@vger.kernel.org, linux-fpga@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, coresight@lists.linaro.org, iommu@lists.linux.dev, linux-amlogic@lists.infradead.org, linux-cxl@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH 02/19] perf/hisilicon: Fix group validation Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250826_041541_548312_553A09F7 X-CRM114-Status: GOOD ( 25.96 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Aug 13, 2025 at 06:00:54PM +0100, Robin Murphy wrote: > The group validation logic shared by the HiSilicon HNS3/PCIe drivers is > a bit off, in that given a software group leader, it will consider that > event *in place of* the actual new event being opened. At worst this > could theoretically allow an unschedulable group if the software event > config happens to look like one of the hardware siblings. > > The uncore framework avoids that particular issue, What is "the uncore framework"? I'm not sure exactly what you're referring to, nor how that composes with the problem described above. > but all 3 also share the common issue of not preventing racy access to > the sibling list, Can you please elaborate on this racy access to the silbing list? I'm not sure exactly what you're referring to. > and some redundant checks which can be cleaned up. > > Signed-off-by: Robin Murphy > --- > drivers/perf/hisilicon/hisi_pcie_pmu.c | 17 ++++++----------- > drivers/perf/hisilicon/hisi_uncore_pmu.c | 23 +++++++---------------- > drivers/perf/hisilicon/hns3_pmu.c | 17 ++++++----------- > 3 files changed, 19 insertions(+), 38 deletions(-) > > diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c > index c5394d007b61..3b0b2f7197d0 100644 > --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c > +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c > @@ -338,21 +338,16 @@ static bool hisi_pcie_pmu_validate_event_group(struct perf_event *event) > int counters = 1; > int num; > > - event_group[0] = leader; > - if (!is_software_event(leader)) { > - if (leader->pmu != event->pmu) > - return false; > + if (leader == event) > + return true; > > - if (leader != event && !hisi_pcie_pmu_cmp_event(leader, event)) > - event_group[counters++] = event; > - } > + event_group[0] = event; > + if (leader->pmu == event->pmu && !hisi_pcie_pmu_cmp_event(leader, event)) > + event_group[counters++] = leader; Looking at this, the existing logic to share counters (which hisi_pcie_pmu_cmp_event() is trying to permit) looks to be bogus, given that the start/stop callbacks will reprogram the HW counters (and hence can fight with one another). I suspect that can be removed *entirely*, and this can be simplified down to allocating N counters, without a quadratic event comparison. We don't try to share counters in other PMU drivers, and there was no rationale for trying to do this when this wa introduced in commit: 8404b0fbc7fbd42e ("drivers/perf: hisi: Add driver for HiSilicon PCIe PMU") The 'link' tag in that comment goes to v13, which doesn't link to prior postings, so I'm not going to dig further. Mark. > > for_each_sibling_event(sibling, event->group_leader) { > - if (is_software_event(sibling)) > - continue; > - > if (sibling->pmu != event->pmu) > - return false; > + continue; > > for (num = 0; num < counters; num++) { > /* > diff --git a/drivers/perf/hisilicon/hisi_uncore_pmu.c b/drivers/perf/hisilicon/hisi_uncore_pmu.c > index a449651f79c9..3c531b36cf25 100644 > --- a/drivers/perf/hisilicon/hisi_uncore_pmu.c > +++ b/drivers/perf/hisilicon/hisi_uncore_pmu.c > @@ -101,26 +101,17 @@ static bool hisi_validate_event_group(struct perf_event *event) > /* Include count for the event */ > int counters = 1; > > - if (!is_software_event(leader)) { > - /* > - * We must NOT create groups containing mixed PMUs, although > - * software events are acceptable > - */ > - if (leader->pmu != event->pmu) > - return false; > + if (leader == event) > + return true; > > - /* Increment counter for the leader */ > - if (leader != event) > - counters++; > - } > + /* Increment counter for the leader */ > + if (leader->pmu == event->pmu) > + counters++; > > for_each_sibling_event(sibling, event->group_leader) { > - if (is_software_event(sibling)) > - continue; > - if (sibling->pmu != event->pmu) > - return false; > /* Increment counter for each sibling */ > - counters++; > + if (sibling->pmu == event->pmu) > + counters++; > } > > /* The group can not count events more than the counters in the HW */ > diff --git a/drivers/perf/hisilicon/hns3_pmu.c b/drivers/perf/hisilicon/hns3_pmu.c > index c157f3572cae..382e469257f9 100644 > --- a/drivers/perf/hisilicon/hns3_pmu.c > +++ b/drivers/perf/hisilicon/hns3_pmu.c > @@ -1058,21 +1058,16 @@ static bool hns3_pmu_validate_event_group(struct perf_event *event) > int counters = 1; > int num; > > - event_group[0] = leader; > - if (!is_software_event(leader)) { > - if (leader->pmu != event->pmu) > - return false; > + if (leader == event) > + return true; > > - if (leader != event && !hns3_pmu_cmp_event(leader, event)) > - event_group[counters++] = event; > - } > + event_group[0] = event; > + if (leader->pmu == event->pmu && !hns3_pmu_cmp_event(leader, event)) > + event_group[counters++] = leader; > > for_each_sibling_event(sibling, event->group_leader) { > - if (is_software_event(sibling)) > - continue; > - > if (sibling->pmu != event->pmu) > - return false; > + continue; > > for (num = 0; num < counters; num++) { > /* > -- > 2.39.2.101.g768bb238c484.dirty >