[PATCH] x86: Fix RCU list usage to avoid false positive warnings

From: madhuparnabhowmik10
Date: Thu Apr 30 2020 - 15:29:51 EST


From: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>

Use list_for_each_entry() instead of list_for_each_entry_rcu() whenever
spinlock or mutex is always held.
Otherwise, pass cond to list_for_each_entry_rcu().

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>
---
arch/x86/kernel/nmi.c | 2 +-
arch/x86/kvm/irq_comm.c | 3 ++-
arch/x86/pci/mmconfig-shared.c | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 6407ea21fa1b..999dc6c134d2 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -195,7 +195,7 @@ void unregister_nmi_handler(unsigned int type, const char *name)

raw_spin_lock_irqsave(&desc->lock, flags);

- list_for_each_entry_rcu(n, &desc->head, list) {
+ list_for_each_entry(n, &desc->head, list) {
/*
* the name passed in to describe the nmi handler
* is used as the lookup key
diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index c47d2acec529..5b88a648e079 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -258,7 +258,8 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, unsigned irqchip, unsigned pin,
idx = srcu_read_lock(&kvm->irq_srcu);
gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin);
if (gsi != -1)
- hlist_for_each_entry_rcu(kimn, &kvm->arch.mask_notifier_list, link)
+ hlist_for_each_entry_rcu(kimn, &kvm->arch.mask_notifier_list, link,
+ srcu_read_lock_held(&kvm->irq_srcu))
if (kimn->irq == gsi)
kimn->func(kimn, mask);
srcu_read_unlock(&kvm->irq_srcu, idx);
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 6fa42e9c4e6f..a096942690bd 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -797,7 +797,7 @@ int pci_mmconfig_delete(u16 seg, u8 start, u8 end)
struct pci_mmcfg_region *cfg;

mutex_lock(&pci_mmcfg_lock);
- list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list)
+ list_for_each_entry(cfg, &pci_mmcfg_list, list)
if (cfg->segment == seg && cfg->start_bus == start &&
cfg->end_bus == end) {
list_del_rcu(&cfg->list);
--
2.17.1