From patchwork Fri Aug 9 21:45:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yabin Cui X-Patchwork-Id: 11087721 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A59FA14D5 for ; Fri, 9 Aug 2019 21:45:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9256F2022B for ; Fri, 9 Aug 2019 21:45:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 86E87223A1; Fri, 9 Aug 2019 21:45:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0C71C2228E for ; Fri, 9 Aug 2019 21:45:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:From:Subject:Mime-Version:Message-Id :Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=TdA/dw9vTGulKllncql4V5qHoaAoAYqX9ip8N6ACN8g=; b=rejyvSkpIHqn8b P99n+YrhZCJH+ua40O8wGaGTedJA5tzxOm6a01t8Fg8Yes3ytd/sxzcSH2u7raO4xaptm/emb/dRk 6M4EbSkWD6pZwQCGyN+trMpZyIhBGnTb+JJDOi6S1rXnIzs3Cv5d3Sna9OrdaWI6B1ByUqZ6Lx99n 0YLCCluh/Wgyp6/uZmpkQqi+js9rRFlex6t05Pa9f04M/EWMVUMGrUju6YN6vZ+/9XV0MO5XKeLnj zmyVpP/Rn4Psk4MfQUvqwxeQjhye5AQcLwnOZX+zxKbZYjRbVA2C1hnEyPXFpdhXy0fbBb97saPI3 sjXL9+ktmGad1sfUwTfQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hwCho-0004ho-Ey; Fri, 09 Aug 2019 21:45:48 +0000 Received: from mail-pf1-x449.google.com ([2607:f8b0:4864:20::449]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hwChk-0004ea-M3 for linux-arm-kernel@lists.infradead.org; Fri, 09 Aug 2019 21:45:46 +0000 Received: by mail-pf1-x449.google.com with SMTP id q67so2486787pfc.10 for ; Fri, 09 Aug 2019 14:45:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=6tkFczY/dvkkIFEc1rtR6Zc8LvZ9pSwYHPfa/X0Paso=; b=wEoB7tUZTCW5+AS5NImPnh1gGOxb1EwZw4FOWS8Kc/dFOzqKipvTD8X2nUqgQhU+k4 eRok0zGoilfIAi7gZS5+da+uS1CxgtR7v9eEH4Nrr9s4YGJFh9/VkIK40nplbLwagTQ9 N5l7slKvKREmdveVoJqNBT0mSNN3h922j/reIAysk+8ieUYLVBTzy9z7mryF3oma93PS 961HyDaifASIWVYvhCo0cGV3yAe8gsjsjVrUSCSIITDX3t0poWrjbIK5OSi0z1lp2Xjr U8OGoWqNC4bkquCCoeZyNLoQwrUImwZlYA8fc9QaJJmZOakgFEP6Ulxqi+fJG/v2L9bC nPCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=6tkFczY/dvkkIFEc1rtR6Zc8LvZ9pSwYHPfa/X0Paso=; b=lpapk6mr55u/ICg3zNJXC91KSWpkFDKf+T+A/i2vr4HEUpGazo5jwCgVPl3xN0NHQb sPc1btN8/sk3guLftKDBm6tSl7iYfn5Y/+MDtms5Oa0d9HTkDEJwzBZD2hLh2HQR7Tga ne8hQ5JkezqyQ5n4qx824PqT8RXlCsOW0ewMRjtYso0qnpUU26FzME7QwZbXrdui8iQ9 VW40GTFOrtZpBz92vcs0TkZ+o4zHPyuhDDHJvD09OEROi2b0YTXsX6+11kKwmGo454ib EoZBgukYSG+blrUDWv/Jf8xU5Z3iX8Ob4oNu1rRugo6KA78YNbeVS98ZW+jsYeMEdIS6 NFsQ== X-Gm-Message-State: APjAAAVaGozsIBZSeRdkrSCT+h4s2WRX7m/eCW/EUsayaP/l/i8NHlix TiQOpYIR0lVOY8Ycb+v5i5Iiqg82Tw== X-Google-Smtp-Source: APXvYqzFEh7O8qf2o48Fv33K5IsiswwPvBLa5bi275a3dGlUPo7TR41h1n+PjPOmFKM8497I52qf9ZqFlWQ= X-Received: by 2002:a65:6497:: with SMTP id e23mr18570776pgv.89.1565387142462; Fri, 09 Aug 2019 14:45:42 -0700 (PDT) Date: Fri, 9 Aug 2019 14:45:38 -0700 Message-Id: <20190809214538.29677-1-yabinc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.23.0.rc1.153.gdeed80330f-goog Subject: [PATCH v2] coresight: Serialize enabling/disabling a link device. From: Yabin Cui To: Mathieu Poirier , Suzuki K Poulose , Alexander Shishkin X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190809_144544_749919_CC77BAD7 X-CRM114-Status: GOOD ( 15.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Yabin Cui , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP When tracing etm data of multiple threads on multiple cpus through perf interface, some link devices are shared between paths of different cpus. It creates race conditions when different cpus wants to enable/disable the same link device at the same time. Example 1: Two cpus want to enable different ports of a coresight funnel, thus calling the funnel enable operation at the same time. But the funnel enable operation isn't reentrantable. Example 2: For an enabled coresight dynamic replicator with refcnt=1, one cpu wants to disable it, while another cpu wants to enable it. Ideally we still have an enabled replicator with refcnt=1 at the end. But in reality the result is uncertain. Since coresight devices claim themselves when enabled for self-hosted usage, the race conditions above usually make the link devices not usable after many cycles. To fix the race conditions, this patch adds a spinlock to serialize enabling/disabling a link device. Signed-off-by: Yabin Cui Reviewed-by: Suzuki K Poulose --- v1 -> v2: extend lock range to protect read of refcnt in coresight_disable_link(). --- drivers/hwtracing/coresight/coresight.c | 12 +++++++++++- include/linux/coresight.h | 3 +++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index 55db77f6410b..e526bdeaeb22 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -256,6 +256,7 @@ static int coresight_enable_link(struct coresight_device *csdev, int ret; int link_subtype; int refport, inport, outport; + unsigned long flags; if (!parent || !child) return -EINVAL; @@ -274,15 +275,18 @@ static int coresight_enable_link(struct coresight_device *csdev, if (refport < 0) return refport; + spin_lock_irqsave(&csdev->spinlock, flags); if (atomic_inc_return(&csdev->refcnt[refport]) == 1) { if (link_ops(csdev)->enable) { ret = link_ops(csdev)->enable(csdev, inport, outport); if (ret) { atomic_dec(&csdev->refcnt[refport]); + spin_unlock_irqrestore(&csdev->spinlock, flags); return ret; } } } + spin_unlock_irqrestore(&csdev->spinlock, flags); csdev->enable = true; @@ -296,6 +300,7 @@ static void coresight_disable_link(struct coresight_device *csdev, int i, nr_conns; int link_subtype; int refport, inport, outport; + unsigned long flags; if (!parent || !child) return; @@ -315,14 +320,18 @@ static void coresight_disable_link(struct coresight_device *csdev, nr_conns = 1; } + spin_lock_irqsave(&csdev->spinlock, flags); if (atomic_dec_return(&csdev->refcnt[refport]) == 0) { if (link_ops(csdev)->disable) link_ops(csdev)->disable(csdev, inport, outport); } for (i = 0; i < nr_conns; i++) - if (atomic_read(&csdev->refcnt[i]) != 0) + if (atomic_read(&csdev->refcnt[i]) != 0) { + spin_unlock_irqrestore(&csdev->spinlock, flags); return; + } + spin_unlock_irqrestore(&csdev->spinlock, flags); csdev->enable = false; } @@ -1225,6 +1234,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) csdev->subtype = desc->subtype; csdev->ops = desc->ops; csdev->orphan = false; + spin_lock_init(&csdev->spinlock); csdev->dev.type = &coresight_dev_type[desc->type]; csdev->dev.groups = desc->groups; diff --git a/include/linux/coresight.h b/include/linux/coresight.h index a2b68823717b..dd28d9ab841d 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -9,6 +9,7 @@ #include #include #include +#include /* Peripheral id registers (0xFD0-0xFEC) */ #define CORESIGHT_PERIPHIDR4 0xfd0 @@ -153,6 +154,7 @@ struct coresight_connection { * activated but not yet enabled. Enabling for a _sink_ * appens when a source has been selected for that it. * @ea: Device attribute for sink representation under PMU directory. + * @spinlock: Serialize enabling/disabling this device. */ struct coresight_device { struct coresight_platform_data *pdata; @@ -166,6 +168,7 @@ struct coresight_device { /* sink specific fields */ bool activated; /* true only if a sink is part of a path */ struct dev_ext_attribute *ea; + spinlock_t spinlock; }; /*