lkml.org 
[lkml]   [2018]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v8 4/5] iommu/arm-smmu: Add the device_link between masters and smmu
On Wed, Mar 7, 2018 at 6:17 PM, Robin Murphy <robin.murphy@arm.com> wrote:
> On 02/03/18 10:10, Vivek Gautam wrote:
>>
>> From: Sricharan R <sricharan@codeaurora.org>
>>
>> Finally add the device link between the master device and
>> smmu, so that the smmu gets runtime enabled/disabled only when the
>> master needs it. This is done from add_device callback which gets
>> called once when the master is added to the smmu.
>>
>> Signed-off-by: Sricharan R <sricharan@codeaurora.org>
>> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
>> ---
>> drivers/iommu/arm-smmu.c | 21 +++++++++++++++++++++
>> 1 file changed, 21 insertions(+)
>>
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index 3d6a1875431f..bb1ea82c1003 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -217,6 +217,9 @@ struct arm_smmu_device {
>> /* IOMMU core code handle */
>> struct iommu_device iommu;
>> +
>> + /* runtime PM link to master */
>> + struct device_link *link;
>
>
> Just the one?
>
>> };
>> enum arm_smmu_context_fmt {
>> @@ -1470,10 +1473,26 @@ static int arm_smmu_add_device(struct device *dev)
>> iommu_device_link(&smmu->iommu, dev);
>> + /*
>> + * Establish the link between smmu and master, so that the
>> + * smmu gets runtime enabled/disabled as per the master's
>> + * needs.
>> + */
>> + smmu->link = device_link_add(dev, smmu->dev, DL_FLAG_PM_RUNTIME);
>
>
> Maybe I've misunderstood how the API works, but AFAICS the second and
> subsequent devices are all just going to overwrite (and leak) the link of
> the previous one...

Sorry, my bad. Will take care of this.

regards
Vivek

>
>> + if (!smmu->link) {
>> + dev_warn(smmu->dev, "Unable to create device link between
>> %s and %s\n",
>> + dev_name(smmu->dev), dev_name(dev));
>> + ret = -ENODEV;
>> + goto out_unlink;
>> + }
>> +
>> arm_smmu_rpm_put(smmu);
>> return 0;
>> +out_unlink:
>> + iommu_device_unlink(&smmu->iommu, dev);
>> + arm_smmu_master_free_smes(fwspec);
>> out_rpm_put:
>> arm_smmu_rpm_put(smmu);
>> out_cfg_free:
>> @@ -1496,6 +1515,8 @@ static void arm_smmu_remove_device(struct device
>> *dev)
>> cfg = fwspec->iommu_priv;
>> smmu = cfg->smmu;
>> + device_link_del(smmu->link);
>
>
> ...and equivalently you end up with a double-free (or more) here of a link
> which may not have belonged to dev anyway.
>
> Robin.
>
>
>> +
>> ret = arm_smmu_rpm_get(smmu);
>> if (ret < 0)
>> return;
>>
>



--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

\
 
 \ /
  Last update: 2018-03-08 07:36    [W:0.065 / U:0.268 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site