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 ECDCFCAC587 for ; Thu, 11 Sep 2025 15:33:39 +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:Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=ff/wyuZO5UIQVkCR2N2KX4E1vX6xd5TgHmsu3ejak7Q=; b=00DbDQES5Dk1InWzSAC4bDbMBx WMzVuHmCJ7xqff737UOZoC/Btwamo69mcgnuJwuMsT1GZFEWzbvck4uXA0w2wQz/mWqXQzdC6YbFG OYHDnRuJ3svE1mNEYV0Id04W6cuulH0OKd6JdJ0KfG9qP9vwVjsU1X3fBFsvq1me24QT3M3sztOkx M3WLSLvjZyNgTa6gIz0Nqig0Z/vEUMrh3CTkWXVe5dd8CYRVhVnPC6lk2m49h5WqylGRBiRQkEQQi UIEyPqhz79HpPjqpcF4iwINbVWki1fvsyql6gmvzcc/5Jz8jB7BVoYoMtPwF0Yq5eLSErjdM5KB5B DbMoDSiw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwjIj-00000003v9b-1Qty; Thu, 11 Sep 2025 15:33:33 +0000 Received: from out-180.mta1.migadu.com ([2001:41d0:203:375::b4]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwjIg-00000003v6a-0cSc for linux-arm-kernel@lists.infradead.org; Thu, 11 Sep 2025 15:33:32 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757604806; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=ff/wyuZO5UIQVkCR2N2KX4E1vX6xd5TgHmsu3ejak7Q=; b=C37DQb3OEJOJsqSu2+34RxAJXBOa8EL9L4biqD5chRL3DhDnVB9duDnfJvNl+Ip2kBMf+o W6h0neeBYXplrNbQuxWPsow9OirZjuPEsGMhg46k+mXfF82dQTipBWqLVlWwLWn79w8NVX 33OYtb0xp0cVFt4l9QgolRLmDJTm8Y8= From: Sean Anderson To: Suzuki K Poulose , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org Cc: Alexander Shishkin , Mike Leach , Linu Cherian , James Clark , linux-kernel@vger.kernel.org, Sean Anderson Subject: [PATCH v2] coresight: Fix possible deadlock in coresight_panic_cb Date: Thu, 11 Sep 2025 11:33:15 -0400 Message-Id: <20250911153315.3607119-1-sean.anderson@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250911_083330_935664_83D49F80 X-CRM114-Status: GOOD ( 15.89 ) 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 coresight_panic_cb is called with interrupts disabled during panics. However, bus_for_each_dev calls bus_to_subsys which takes bus_kset->list_lock without disabling IRQs. This will cause a deadlock if a panic occurs while one of the other coresight functions that uses bus_for_each_dev is running. Maintain a separate list of coresight devices to access during a panic. Fixes: 46006ceb5d02 ("coresight: core: Add provision for panic callbacks") Signed-off-by: Sean Anderson --- Changes in v2: - Add a comment describing csdev_lock/list - Consolidate list removal in coresight_device_release drivers/hwtracing/coresight/coresight-core.c | 43 +++++++++++--------- include/linux/coresight.h | 1 + 2 files changed, 25 insertions(+), 19 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index fa758cc21827..4e28e56f2e30 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1042,10 +1042,19 @@ static void coresight_clear_default_sink(struct coresight_device *csdev) } } +/* + * Dedicated list of devices for use by during panic (which may occur with + * interrupts disabled). + */ +static DEFINE_SPINLOCK(csdev_lock); +static LIST_HEAD(csdev_list); + static void coresight_device_release(struct device *dev) { struct coresight_device *csdev = to_coresight_device(dev); + scoped_guard(spinlock_irq, &csdev_lock) + list_del(&csdev->csdev_list); fwnode_handle_put(csdev->dev.fwnode); free_percpu(csdev->perf_sink_id_map.cpu_map); kfree(csdev); @@ -1357,6 +1366,10 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) goto err_out; } } + + scoped_guard(spinlock_irq, &csdev_lock) + list_add(&csdev->csdev_list, &csdev_list); + /* * Make sure the device registration and the connection fixup * are synchronised, so that we don't see uninitialised devices @@ -1563,28 +1576,20 @@ const struct bus_type coresight_bustype = { .name = "coresight", }; -static int coresight_panic_sync(struct device *dev, void *data) -{ - int mode; - struct coresight_device *csdev; - - /* Run through panic sync handlers for all enabled devices */ - csdev = container_of(dev, struct coresight_device, dev); - mode = coresight_get_mode(csdev); - - if ((mode == CS_MODE_SYSFS) || (mode == CS_MODE_PERF)) { - if (panic_ops(csdev)) - panic_ops(csdev)->sync(csdev); - } - - return 0; -} - static int coresight_panic_cb(struct notifier_block *self, unsigned long v, void *p) { - bus_for_each_dev(&coresight_bustype, NULL, NULL, - coresight_panic_sync); + struct coresight_device *csdev; + + guard(spinlock)(&csdev_lock); + list_for_each_entry(csdev, &csdev_list, csdev_list) { + /* Run through panic sync handlers for all enabled devices */ + int mode = coresight_get_mode(csdev); + + if ((mode == CS_MODE_SYSFS || mode == CS_MODE_PERF) && + panic_ops(csdev)) + panic_ops(csdev)->sync(csdev); + } return 0; } diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 4ac65c68bbf4..a5e62ebd03b5 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -302,6 +302,7 @@ struct coresight_device { /* system configuration and feature lists */ struct list_head feature_csdev_list; struct list_head config_csdev_list; + struct list_head csdev_list; raw_spinlock_t cscfg_csdev_lock; void *active_cscfg_ctxt; }; -- 2.35.1.1320.gc452695387.dirty