iommu/vt-d: Silence RCU-list debugging warning in dmar_find_atsr()

dmar_find_atsr() calls list_for_each_entry_rcu() outside of an RCU read
side critical section but with dmar_global_lock held. Silence this
false positive.

 drivers/iommu/intel-iommu.c:4504 RCU-list traversed in non-reader section!!
 1 lock held by swapper/0/1:
 #0: ffffffff9755bee8 (dmar_global_lock){+.+.}, at: intel_iommu_init+0x1a6/0xe19

 Call Trace:
  dump_stack+0xa4/0xfe
  lockdep_rcu_suspicious+0xeb/0xf5
  dmar_find_atsr+0x1ab/0x1c0
  dmar_parse_one_atsr+0x64/0x220
  dmar_walk_remapping_entries+0x130/0x380
  dmar_table_init+0x166/0x243
  intel_iommu_init+0x1ab/0xe19
  pci_iommu_init+0x1a/0x44
  do_one_initcall+0xae/0x4d0
  kernel_init_freeable+0x412/0x4c5
  kernel_init+0x19/0x193

Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 4be549478691884f75e148ed5e1bd23b84a23ac9..ef0a5246700e546d025c668aa58b8d5349e14946 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4501,7 +4501,8 @@ static struct dmar_atsr_unit *dmar_find_atsr(struct acpi_dmar_atsr *atsr)
        struct dmar_atsr_unit *atsru;
        struct acpi_dmar_atsr *tmp;
 
-       list_for_each_entry_rcu(atsru, &dmar_atsr_units, list) {
+       list_for_each_entry_rcu(atsru, &dmar_atsr_units, list,
+                               dmar_rcu_check()) {
                tmp = (struct acpi_dmar_atsr *)atsru->hdr;
                if (atsr->segment != tmp->segment)
                        continue;