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From: Amol Grover <frextrite@gmail.com>
To: Allison Randal <allison@lohutok.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>, Qian Cai <cai@lca.pw>,
	Deepa Dinamani <deepa.kernel@gmail.com>,
	Joerg Roedel <joro@8bytes.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>,
	linux-kernel@vger.kernel.org,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH RESEND] iommu: dmar: Fix RCU list debugging warnings
Date: Sun, 23 Feb 2020 22:25:39 +0530	[thread overview]
Message-ID: <20200223165538.29870-1-frextrite@gmail.com> (raw)

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>
---
 include/linux/dmar.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index f64ca27dc210..712be8bc6a7c 100644
--- 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)
-- 
2.24.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

WARNING: multiple messages have this Message-ID (diff)
From: Amol Grover <frextrite@gmail.com>
To: Allison Randal <allison@lohutok.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>, Qian Cai <cai@lca.pw>,
	Deepa Dinamani <deepa.kernel@gmail.com>,
	Joerg Roedel <joro@8bytes.org>
Cc: linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Joel Fernandes <joel@joelfernandes.org>,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Amol Grover <frextrite@gmail.com>
Subject: [PATCH RESEND] iommu: dmar: Fix RCU list debugging warnings
Date: Sun, 23 Feb 2020 22:25:39 +0530	[thread overview]
Message-ID: <20200223165538.29870-1-frextrite@gmail.com> (raw)

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>
---
 include/linux/dmar.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index f64ca27dc210..712be8bc6a7c 100644
--- 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)
-- 
2.24.1


             reply	other threads:[~2020-02-23 16:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-23 16:55 Amol Grover [this message]
2020-02-23 16:55 ` [PATCH RESEND] iommu: dmar: Fix RCU list debugging warnings Amol Grover
2020-02-23 23:34 ` [Linux-kernel-mentees] " Lu Baolu
2020-02-23 23:34   ` Lu Baolu
2020-03-02 16:04 ` [Linux-kernel-mentees] " Joerg Roedel
2020-03-02 16:04   ` Joerg Roedel

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