From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id EA242224AED for ; Wed, 14 May 2025 09:15:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747214115; cv=none; b=rXnRdYtZ1wjV5ZRlOpgmO9rLlko/brOIzhive5QGQs/8M1PkP3hQqte8kYCW/21YqH2TjnnwAWjopiKS35NAwCZ80c3Gz4clbSK5n+xKcLXozPrU4zo3QD7mmp5OJqhu8vuxYQ07mNj46oQvbNuEZzlKNJM+F9ZYrrO4lEtWTI4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747214115; c=relaxed/simple; bh=kxxTgdmGJNsrlf4IcgzT3n0S5zAAcuol3ADDvF6vPOQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I0gRDL4Y2dudpYuamkFaHXJAfgU9tHzt25fwDMxBzn8C/CUzjyEJbT4d1PS7PRWSQMitNv4dgsBc4VpXD2oteBDm8yItaH9TIQ+MTr+KljQ6vQ2C9nXkkE8dDWjPEQXShCy/Dyoxfmtvz9PNRzfRTe/k80JiK/V10krRnyBV+wI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 109D715A1; Wed, 14 May 2025 02:15:01 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CCB213F5A1; Wed, 14 May 2025 02:15:11 -0700 (PDT) Date: Wed, 14 May 2025 10:15:09 +0100 From: Leo Yan To: Yeoreum Yun Cc: suzuki.poulose@arm.com, mike.leach@linaro.org, james.clark@linaro.org, alexander.shishkin@linux.intel.com, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 2/3] coresight: holding cscfg_csdev_lock while removing cscfg from csdev Message-ID: <20250514091509.GD26114@e132581.arm.com> References: <20250513170622.3071637-1-yeoreum.yun@arm.com> <20250513170622.3071637-2-yeoreum.yun@arm.com> <20250513170622.3071637-3-yeoreum.yun@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250513170622.3071637-3-yeoreum.yun@arm.com> On Tue, May 13, 2025 at 06:06:21PM +0100, Yeoreum Yun wrote: > There'll be possible race scenario for coresight config: > > CPU0 CPU1 > (perf enable) load module > cscfg_load_config_sets() > activate config. // sysfs > (sys_active_cnt == 1) > ... > cscfg_csdev_enable_active_config() > lock(csdev->cscfg_csdev_lock) > deactivate config // sysfs > (sys_activec_cnt == 0) > cscfg_unload_config_sets() > cscfg_remove_owned_csdev_configs() > // here load config activate by CPU1 > unlock(csdev->cscfg_csdev_lock) > > iterating config_csdev_list could be raced with config_csdev_list's > entry delete. > > To resolve this race , hold csdev->cscfg_csdev_lock() while > cscfg_remove_owned_csdev_configs() > > Signed-off-by: Yeoreum Yun > Fixes: 02bd588e12df ("coresight: configuration: Update API to permit dynamic load/unload") > --- > drivers/hwtracing/coresight/coresight-syscfg.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index a70c1454b410..5d194b9269f5 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -391,14 +391,17 @@ static void cscfg_owner_put(struct cscfg_load_owner_info *owner_info) > static void cscfg_remove_owned_csdev_configs(struct coresight_device *csdev, void *load_owner) > { > struct cscfg_config_csdev *config_csdev, *tmp; > + unsigned long flags; > > if (list_empty(&csdev->config_csdev_list)) > return; > > + raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags); Could we use the format: guard(raw_spinlock_irqsave)(&csdev->cscfg_csdev_lock); Sorry I did not mention this in the earlier review. Otherwise: Reviewed-by: Leo Yan > list_for_each_entry_safe(config_csdev, tmp, &csdev->config_csdev_list, node) { > if (config_csdev->config_desc->load_owner == load_owner) > list_del(&config_csdev->node); > } > + raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > } > > static void cscfg_remove_owned_csdev_features(struct coresight_device *csdev, void *load_owner) > -- > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} >