linux-kernel - [PATCH 5.5 073/170] iommu/vt-d: Silence RCU-list debugging warnings

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Message-Id: <20200331085432.115748881@linuxfoundation.org>
Date:   Tue, 31 Mar 2020 10:58:07 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Qian Cai <cai@....pw>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <jroedel@...e.de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.5 073/170] iommu/vt-d: Silence RCU-list debugging warnings

From: Qian Cai <cai@....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@....pw>
Acked-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.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 93f8e646cb0b0..f7a86652a9841 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 712be8bc6a7c8..d7bf029df737d 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