Commit 02d715b4 authored Feb 23, 2020 by Amol Grover Committed by Joerg Roedel Mar 02, 2020

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>

parent 98d54f81

include/linux/dmar.h

+5 −3

Original line number	Diff line number	Diff line
		@@ -70,7 +70,8 @@ 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)
		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)

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