From patchwork Tue Mar 24 05:29:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Andersson X-Patchwork-Id: 11454497 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1E85C1392 for ; Tue, 24 Mar 2020 05:29:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F343420663 for ; Tue, 24 Mar 2020 05:29:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="AeJERwRS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725905AbgCXF3L (ORCPT ); Tue, 24 Mar 2020 01:29:11 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:43882 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725869AbgCXF3L (ORCPT ); Tue, 24 Mar 2020 01:29:11 -0400 Received: by mail-pf1-f193.google.com with SMTP id f206so8722499pfa.10 for ; Mon, 23 Mar 2020 22:29:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=GksRJuQygj8iEw4+FLEhSTTKNuAXjcLxWomfet7/TQc=; b=AeJERwRSpJgnUUI1sktI8LwnrhuSGSz3vYH1BFGxcVqWMRFulqPzEU+WQgIDtowBid DY0kGUla4Ru00rBlZA6ZdZE8lKd1/wJoWuf0lfY+cj2pDSnteABWfDjOZQsvKM+QFXa3 sMkhhNfGBHxaoBmA97f4vTJUIS1/CiwlZbeWU+TAt0eAlf/M7HCTuKV4oURSn8ECY4sC iX3F68HmPtaSvXgjFbClRcp4WaMOa4pIhb2bRBGX1JuaJ2bryB0/Lnge5pkrunV1IAMe 3x+OLXURB5P9kmJSJkyX2vCL4/RwyaFE97vy31wFojuM9pWgkikB1TK966do/hubMOas w5LQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=GksRJuQygj8iEw4+FLEhSTTKNuAXjcLxWomfet7/TQc=; b=lRi47HmIoxFIJu41yxmLnYlP8swfCJOH8cwNBgirxJXPpC9CPRYq+AfscOCMCzMUvr SgWp2ydMh2y0c84KbdQndkUnTt6e/KX1PEvAhhjsKa7/C0MMFgY8u5I1+Os1wYBa8TKt ZR1sNd7C1Wq/iyD+K5xiIVlmvUaaUTJ/lCMqJq9ntSH3vLGZL8b4i3Ys+gcK7ieHKF8q zIgNKmTFvFmKxX8lIovv8nRbUjQ7H1qduF5ivrPXTCsnTjxOna21Lba9T7b0Z6w5ZYKU WXIq9p+tQrcikVxMvpkoX1cJC7S5pN9KRSjG+I1nu5UWOXfpWAy/ZQ1ev05upu2oIKrA IcVg== X-Gm-Message-State: ANhLgQ3T5GTEz7l1mCVWbcSBi5owBzeKdKAyKc2+v+ESp+XU6om5p1UI 1nFeED/4LNRDl1/7q75CSruPOA== X-Google-Smtp-Source: ADFU+vvQ57kvoZi+N9uQpIwZoXOTeauhh9IYgweVQ3UD9AqMO2B6kX+AF3DFoI0AvOUD007/H1wUOw== X-Received: by 2002:a62:4e4c:: with SMTP id c73mr28422516pfb.254.1585027750135; Mon, 23 Mar 2020 22:29:10 -0700 (PDT) Received: from localhost.localdomain (104-188-17-28.lightspeed.sndgca.sbcglobal.net. [104.188.17.28]) by smtp.gmail.com with ESMTPSA id j14sm2795413pgk.74.2020.03.23.22.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Mar 2020 22:29:09 -0700 (PDT) From: Bjorn Andersson To: Andy Gross , Bjorn Andersson , Ohad Ben-Cohen Cc: linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, Mathieu Poirier Subject: [PATCH v5 1/4] remoteproc: Traverse rproc_list under RCU read lock Date: Mon, 23 Mar 2020 22:29:01 -0700 Message-Id: <20200324052904.738594-2-bjorn.andersson@linaro.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20200324052904.738594-1-bjorn.andersson@linaro.org> References: <20200324052904.738594-1-bjorn.andersson@linaro.org> MIME-Version: 1.0 Sender: linux-remoteproc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org In order to be able to traverse the mostly read-only rproc_list without locking during panic migrate traversal to be done under rcu_read_lock(). Mutual exclusion for modifications of the list continues to be handled by the rproc_list_mutex and a synchronization point is added before releasing objects that are popped from the list. Reviewed-by: Mathieu Poirier Signed-off-by: Bjorn Andersson --- Changes since v4: - Added rculist include - Picked up Mathieu's r-b drivers/remoteproc/remoteproc_core.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c index a9ac1d01e09b..7ee976ee2044 100644 --- a/drivers/remoteproc/remoteproc_core.c +++ b/drivers/remoteproc/remoteproc_core.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include #include @@ -1868,8 +1869,8 @@ struct rproc *rproc_get_by_phandle(phandle phandle) if (!np) return NULL; - mutex_lock(&rproc_list_mutex); - list_for_each_entry(r, &rproc_list, node) { + rcu_read_lock(); + list_for_each_entry_rcu(r, &rproc_list, node) { if (r->dev.parent && r->dev.parent->of_node == np) { /* prevent underlying implementation from being removed */ if (!try_module_get(r->dev.parent->driver->owner)) { @@ -1882,7 +1883,7 @@ struct rproc *rproc_get_by_phandle(phandle phandle) break; } } - mutex_unlock(&rproc_list_mutex); + rcu_read_unlock(); of_node_put(np); @@ -1939,7 +1940,7 @@ int rproc_add(struct rproc *rproc) /* expose to rproc_get_by_phandle users */ mutex_lock(&rproc_list_mutex); - list_add(&rproc->node, &rproc_list); + list_add_rcu(&rproc->node, &rproc_list); mutex_unlock(&rproc_list_mutex); return 0; @@ -2156,9 +2157,12 @@ int rproc_del(struct rproc *rproc) /* the rproc is downref'ed as soon as it's removed from the klist */ mutex_lock(&rproc_list_mutex); - list_del(&rproc->node); + list_del_rcu(&rproc->node); mutex_unlock(&rproc_list_mutex); + /* Ensure that no readers of rproc_list are still active */ + synchronize_rcu(); + device_del(&rproc->dev); return 0;