This patch fixes the following warning.
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
include/linux/kvm_host.h:259 invoked rcu_dereference_check() without
protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
no locks held by qemu-system-x86/29679.
stack backtrace:
Pid: 29679, comm: qemu-system-x86 Not tainted 2.6.35-rc3+ #200
Call Trace:
[<ffffffff810a224e>] lockdep_rcu_dereference+0xa8/0xb1
[<ffffffffa018a06f>] kvm_iommu_unmap_memslots+0xc9/0xde [kvm]
[<ffffffffa018a0c4>] kvm_iommu_unmap_guest+0x40/0x4e [kvm]
[<ffffffffa018f772>] kvm_arch_destroy_vm+0x1a/0x186 [kvm]
[<ffffffffa01800d0>] kvm_put_kvm+0x110/0x167 [kvm]
[<ffffffffa0180ecc>] kvm_vcpu_release+0x18/0x1c [kvm]
[<ffffffff81156f5d>] fput+0x22a/0x3a0
[<ffffffff81152288>] filp_close+0xb4/0xcd
[<ffffffff8106599f>] put_files_struct+0x1b7/0x36b
[<ffffffff81065830>] ? put_files_struct+0x48/0x36b
[<ffffffff8131ee59>] ? do_raw_spin_unlock+0x118/0x160
[<ffffffff81065bc0>] exit_files+0x6d/0x75
[<ffffffff81068348>] do_exit+0x47d/0xc60
[<ffffffff8177e7b5>] ? _raw_spin_unlock_irq+0x30/0x36
[<ffffffff81068bfa>] do_group_exit+0xcf/0x134
[<ffffffff81080790>] get_signal_to_deliver+0x732/0x81d
[<ffffffff81095996>] ? cpu_clock+0x4e/0x60
[<ffffffff81002082>] do_notify_resume+0x117/0xc43
[<ffffffff810a2fa3>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81080d79>] ? sys_rt_sigtimedwait+0x2b5/0x3bf
[<ffffffff8177d9f2>] ? trace_hardirqs_off_thunk+0x3a/0x3c
[<ffffffff81003221>] ? sysret_signal+0x5/0x3d
[<ffffffff8100343b>] int_signal+0x12/0x17
Signed-off-by: Sheng Yang <sheng@xxxxxxxxxxxxxxx>
---
I just realized the first version of patch unnecessarily covered
kvm_iommu_map_memslots(), because that part had already been
covered by kvm_vm_ioctl_assign_device() definitely(though unpaired
callings seems a little strange...).
virt/kvm/iommu.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 673c88a..c050f32 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -285,15 +285,17 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
static int kvm_iommu_unmap_memslots(struct kvm *kvm)
{
- int i;
+ int i, idx;
struct kvm_memslots *slots;
+ idx = srcu_read_lock(&kvm->srcu);
slots = kvm_memslots(kvm);
for (i = 0; i < slots->nmemslots; i++) {
kvm_iommu_put_pages(kvm, slots->memslots[i].base_gfn,
slots->memslots[i].npages);
}
+ srcu_read_unlock(&kvm->srcu, idx);
return 0;
}
--
1.7.0.1
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