iommu/vt-d: Fix RCU list debugging warnings

dmar_drhd_units is traversed using list_for_each_entry_rcu()
outside of an RCU read side critical section but under the
protection of dmar_global_lock. Hence add corresponding lockdep
expression to silence the following false-positive warnings:

[    1.603975] =============================
[    1.603976] WARNING: suspicious RCU usage
[    1.603977] 5.5.4-stable #17 Not tainted
[    1.603978] -----------------------------
[    1.603980] drivers/iommu/intel-iommu.c:4769 RCU-list traversed in non-reader section!!

[    1.603869] =============================
[    1.603870] WARNING: suspicious RCU usage
[    1.603872] 5.5.4-stable #17 Not tainted
[    1.603874] -----------------------------
[    1.603875] drivers/iommu/dmar.c:293 RCU-list traversed in non-reader section!!

Tested-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Signed-off-by: Amol Grover <frextrite@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index f64ca27dc210469a9da89ac4083bd0532e2abf29..712be8bc6a7c815ba0c46ff3fc88b2218d643272 100644 (file)
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -69,8 +69,9 @@ struct dmar_pci_notify_info {
 extern struct rw_semaphore dmar_global_lock;
 extern struct list_head dmar_drhd_units;
 
-#define for_each_drhd_unit(drhd) \
-       list_for_each_entry_rcu(drhd, &dmar_drhd_units, list)
+#define for_each_drhd_unit(drhd)                                       \
+       list_for_each_entry_rcu(drhd, &dmar_drhd_units, list,           \
+                               dmar_rcu_check())
 
 #define for_each_active_drhd_unit(drhd)                                        \
        list_for_each_entry_rcu(drhd, &dmar_drhd_units, list)           \
@@ -81,7 +82,8 @@ extern struct list_head dmar_drhd_units;
                if (i=drhd->iommu, drhd->ignored) {} else
 
 #define for_each_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, 0) {} else 
 
 static inline bool dmar_rcu_check(void)