linux-kernel - Re: [PATCH v13 03/15] iommu/arm-smmu-v3: Maintain a SID->device structure

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Date:   Mon, 1 Feb 2021 16:15:29 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Keqian Zhu <zhukeqian1@...wei.com>
Cc:     Eric Auger <eric.auger@...hat.com>, eric.auger.pro@...il.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, will@...nel.org,
        joro@...tes.org, maz@...nel.org, robin.murphy@....com,
        alex.williamson@...hat.com, jacob.jun.pan@...ux.intel.com,
        nicoleotsuka@...il.com, vivek.gautam@....com, yi.l.liu@...el.com,
        zhangfei.gao@...aro.org
Subject: Re: [PATCH v13 03/15] iommu/arm-smmu-v3: Maintain a SID->device
 structure

On Mon, Feb 01, 2021 at 08:26:41PM +0800, Keqian Zhu wrote:
> > +static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
> > +				  struct arm_smmu_master *master)
> > +{
> > +	int i;
> > +	int ret = 0;
> > +	struct arm_smmu_stream *new_stream, *cur_stream;
> > +	struct rb_node **new_node, *parent_node = NULL;
> > +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
> > +
> > +	master->streams = kcalloc(fwspec->num_ids,
> > +				  sizeof(struct arm_smmu_stream), GFP_KERNEL);
> > +	if (!master->streams)
> > +		return -ENOMEM;
> > +	master->num_streams = fwspec->num_ids;
> This is not roll-backed when fail.

No need, the caller frees master

> > +
> > +	mutex_lock(&smmu->streams_mutex);
> > +	for (i = 0; i < fwspec->num_ids && !ret; i++) {
> Check ret at here, makes it hard to decide the start index of rollback.
> 
> If we fail at here, then start index is (i-2).
> If we fail in the loop, then start index is (i-1).
> 
[...]
> > +	if (ret) {
> > +		for (; i > 0; i--)
> should be (i >= 0)?
> And the start index seems not correct.

Indeed, this whole bit is wrong. I'll fix it while resending the IOPF
series.

Thanks,
Jean