[PATCH 5.4 065/155] iommu/vt-d: Silence RCU-list debugging warnings

Greg Kroah-Hartman
2020-03-31T09:16:12Z

From: Qian Cai <cai@lca.pw>

[ Upstream commit f5152416528c2295f35dd9c9bd4fb27c4032413d ]

Similar to the commit 02d715b4a818 ("iommu/vt-d: Fix RCU list debugging
warnings"), there are several other places that call
list_for_each_entry_rcu() outside of an RCU read side critical section
but with dmar_global_lock held. Silence those false positives as well.

drivers/iommu/intel-iommu.c:4288 RCU-list traversed in non-reader section!!
1 lock held by swapper/0/1:
#0: ffffffff935892c8 (dmar_global_lock){+.+.}, at: intel_iommu_init+0x1ad/0xb97

drivers/iommu/dmar.c:366 RCU-list traversed in non-reader section!!
1 lock held by swapper/0/1:
#0: ffffffff935892c8 (dmar_global_lock){+.+.}, at: intel_iommu_init+0x125/0xb97

drivers/iommu/intel-iommu.c:5057 RCU-list traversed in non-reader section!!
1 lock held by swapper/0/1:
#0: ffffffffa71892c8 (dmar_global_lock){++++}, at: intel_iommu_init+0x61a/0xb13

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/dmar.c | 3 ++-
include/linux/dmar.h | 6 ++++--
2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 6a9a1b987520f..9e393b9c50911 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -371,7 +371,8 @@ dmar_find_dmaru(struct acpi_dmar_hardware_unit *drhd)
{
struct dmar_drhd_unit *dmaru;

- list_for_each_entry_rcu(dmaru, &dmar_drhd_units, list)
+ list_for_each_entry_rcu(dmaru, &dmar_drhd_units, list,
+ dmar_rcu_check())
if (dmaru->segment == drhd->segment &&
dmaru->reg_base_addr == drhd->address)
return dmaru;
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index d3ea390336f39..f397e52c2d9de 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -74,11 +74,13 @@ extern struct list_head dmar_drhd_units;
dmar_rcu_check())

#define for_each_active_drhd_unit(drhd) \
- list_for_each_entry_rcu(drhd, &dmar_drhd_units, list) \
+ list_for_each_entry_rcu(drhd, &dmar_drhd_units, list, \
+ dmar_rcu_check()) \
if (drhd->ignored) {} else

#define for_each_active_iommu(i, drhd) \
- list_for_each_entry_rcu(drhd, &dmar_drhd_units, list) \
+ list_for_each_entry_rcu(drhd, &dmar_drhd_units, list, \
+ dmar_rcu_check()) \
if (i=drhd->iommu, drhd->ignored) {} else

#define for_each_iommu(i, drhd) \
--
2.20.1