From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751167AbeAVLrW (ORCPT ); Mon, 22 Jan 2018 06:47:22 -0500 Received: from foss.arm.com ([217.140.101.70]:57684 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751020AbeAVLrU (ORCPT ); Mon, 22 Jan 2018 06:47:20 -0500 Subject: Re: [PATCH] ARM-SMMU: Delete error messages for a failed memory allocation in three functions To: SF Markus Elfring , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, =?UTF-8?B?SsO2cmcgUsO2ZGVs?= , Will Deacon Cc: LKML , kernel-janitors@vger.kernel.org References: From: Robin Murphy Message-ID: Date: Mon, 22 Jan 2018 11:47:13 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/01/18 14:36, SF Markus Elfring wrote: > From: Markus Elfring > Date: Sat, 20 Jan 2018 15:30:17 +0100 > > Omit extra messages for a memory allocation failure in these functions. Why? It's your job as patch author to convince reviewers and maintainers why your change is a good thing and they should spend their time looking at it, much less consider merging it. This may as well be "delete some stuff because I feel like it". Do bear in mind the nature of these drivers; Arm SMMUs are not something you find in microcontrollers. On systems using these drivers, it will make no difference whatsoever to anyone if the many-megabyte kernel image is 47 bytes (or whatever) smaller. > This issue was detected by using the Coccinelle software. I think I'm going to have to start treating mention of Coccinelle as a potential disclaimer saying "I haven't attempted to understand the code I'm changing" :( > Signed-off-by: Markus Elfring > --- > drivers/iommu/arm-smmu-v3.c | 9 +++------ > drivers/iommu/arm-smmu.c | 9 +++------ > 2 files changed, 6 insertions(+), 12 deletions(-) > > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c > index f122071688fd..5c2a7103d494 100644 > --- a/drivers/iommu/arm-smmu-v3.c > +++ b/drivers/iommu/arm-smmu-v3.c > @@ -2134,10 +2134,8 @@ static int arm_smmu_init_l1_strtab(struct arm_smmu_device *smmu) > void *strtab = smmu->strtab_cfg.strtab; > > cfg->l1_desc = devm_kzalloc(smmu->dev, size, GFP_KERNEL); > - if (!cfg->l1_desc) { > - dev_err(smmu->dev, "failed to allocate l1 stream table desc\n"); OK, I'll stop playing *completely* dumb; I do know you would get a splat if kmalloc() ever did fail. But what you're removing isn't printk("failed to allocate memory\n"), it's a message which says exactly what allocation failed *for which device*. Can you clarify how I'm going to diagnose this particular problem from the generic splat when all I have is en email from a customer with a dmesg dump? > + if (!cfg->l1_desc) > return -ENOMEM; > - } > > for (i = 0; i < cfg->num_l1_ents; ++i) { > arm_smmu_write_strtab_l1_desc(strtab, &cfg->l1_desc[i]); > @@ -2828,10 +2826,9 @@ static int arm_smmu_device_probe(struct platform_device *pdev) > bool bypass; > > smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL); > - if (!smmu) { > - dev_err(dev, "failed to allocate arm_smmu_device\n"); > + if (!smmu) > return -ENOMEM; > - } > + > smmu->dev = dev; > > if (dev->of_node) { > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 78d4c6b8f1ba..a4da4a870a2e 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -2048,10 +2048,9 @@ static int arm_smmu_device_probe(struct platform_device *pdev) > int num_irqs, i, err; > > smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL); > - if (!smmu) { > - dev_err(dev, "failed to allocate arm_smmu_device\n"); > + if (!smmu) > return -ENOMEM; > - } > + > smmu->dev = dev; > > if (dev->of_node) > @@ -2084,10 +2083,8 @@ static int arm_smmu_device_probe(struct platform_device *pdev) > > smmu->irqs = devm_kzalloc(dev, sizeof(*smmu->irqs) * num_irqs, > GFP_KERNEL); > - if (!smmu->irqs) { > - dev_err(dev, "failed to allocate %d irqs\n", num_irqs); This more than any other is removing potentially useful information: "failed to allocate 37890756 irqs", for instance, would indicate a bug which is very much *not* an out-of-memory condition. Robin. > + if (!smmu->irqs) > return -ENOMEM; > - } > > for (i = 0; i < num_irqs; ++i) { > int irq = platform_get_irq(pdev, i); >