On 2022/6/14 15:16, Tian, Kevin wrote:
From: Lu Baolu <baolu...@linux.intel.com>
Sent: Tuesday, June 14, 2022 10:52 AM
The device_domain_lock is used to protect the device tracking list of
a domain. Remove unnecessary spin_lock/unlock()'s and move the necessary
ones around the list access.
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
drivers/iommu/intel/iommu.c | 68 +++++++++++++++----------------------
1 file changed, 27 insertions(+), 41 deletions(-)
[...]
+iommu_support_dev_iotlb(struct dmar_domain *domain, struct
intel_iommu *iommu,
+ u8 bus, u8 devfn)
{
- struct device_domain_info *info;
-
- assert_spin_locked(&device_domain_lock);
+ struct device_domain_info *info = NULL, *tmp;
+ unsigned long flags;
if (!iommu->qi)
return NULL;
- list_for_each_entry(info, &domain->devices, link)
- if (info->iommu == iommu && info->bus == bus &&
- info->devfn == devfn) {
- if (info->ats_supported && info->dev)
- return info;
+ spin_lock_irqsave(&device_domain_lock, flags);
+ list_for_each_entry(tmp, &domain->devices, link) {
+ if (tmp->iommu == iommu && tmp->bus == bus &&
+ tmp->devfn == devfn) {
+ if (tmp->ats_supported)
+ info = tmp;
Directly returning with unlock here is clearer than adding
another tmp variable...
Sure.
@@ -2460,15 +2450,14 @@ static int domain_add_dev_info(struct
dmar_domain *domain, struct device *dev)
if (!iommu)
return -ENODEV;
- spin_lock_irqsave(&device_domain_lock, flags);
- info->domain = domain;
ret = domain_attach_iommu(domain, iommu);
- if (ret) {
- spin_unlock_irqrestore(&device_domain_lock, flags);
+ if (ret)
return ret;
- }
+
+ spin_lock_irqsave(&device_domain_lock, flags);
list_add(&info->link, &domain->devices);
spin_unlock_irqrestore(&device_domain_lock, flags);
+ info->domain = domain;
This is incorrect. You need fully initialize the object before adding
it to the list. Otherwise a search right after above unlock and
before assigning info->domain will get a wrong data
Fair enough. Will fix it in the next version.
Best regards,
baolu
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