From: Qian Cai <cai@lca.pw>
To: jroedel@suse.de
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: [PATCH] iommu/vt-d: silence a RCU-list debugging warning
Date: Tue, 17 Mar 2020 11:03:26 -0400 [thread overview]
Message-ID: <20200317150326.1659-1-cai@lca.pw> (raw)
dmar_find_atsr() calls list_for_each_entry_rcu() outside of an RCU read
side critical section but with dmar_global_lock held. Silence this
false positive.
drivers/iommu/intel-iommu.c:4504 RCU-list traversed in non-reader section!!
1 lock held by swapper/0/1:
#0: ffffffff9755bee8 (dmar_global_lock){+.+.}, at: intel_iommu_init+0x1a6/0xe19
Call Trace:
dump_stack+0xa4/0xfe
lockdep_rcu_suspicious+0xeb/0xf5
dmar_find_atsr+0x1ab/0x1c0
dmar_parse_one_atsr+0x64/0x220
dmar_walk_remapping_entries+0x130/0x380
dmar_table_init+0x166/0x243
intel_iommu_init+0x1ab/0xe19
pci_iommu_init+0x1a/0x44
do_one_initcall+0xae/0x4d0
kernel_init_freeable+0x412/0x4c5
kernel_init+0x19/0x193
Signed-off-by: Qian Cai <cai@lca.pw>
---
drivers/iommu/intel-iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 4be549478691..ef0a5246700e 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4501,7 +4501,8 @@ static struct dmar_atsr_unit *dmar_find_atsr(struct acpi_dmar_atsr *atsr)
struct dmar_atsr_unit *atsru;
struct acpi_dmar_atsr *tmp;
- list_for_each_entry_rcu(atsru, &dmar_atsr_units, list) {
+ list_for_each_entry_rcu(atsru, &dmar_atsr_units, list,
+ dmar_rcu_check()) {
tmp = (struct acpi_dmar_atsr *)atsru->hdr;
if (atsr->segment != tmp->segment)
continue;
--
2.21.0 (Apple Git-122.2)
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next reply other threads:[~2020-03-17 15:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 15:03 Qian Cai [this message]
2020-03-18 5:27 ` [PATCH] iommu/vt-d: silence a RCU-list debugging warning Lu Baolu
2020-03-18 11:14 ` Qian Cai
2020-03-19 14:16 ` Joerg Roedel
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