Previously this code assumed nothing would mess with current->state between the set_current_state() and schedule(). However the call to kvm_vcpu_check_block() in between might end up requiring locks or other actions, which would change current->state. A similar pattern was described in the "The problem with nested sleeping primitives" LWN article[0]. [0] https://lwn.net/Articles/628628 Signed-off-by: Space Meyer <spm@xxxxxxxxxx> --- virt/kvm/kvm_main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index fab4d37905785..64e10d73f2a92 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -32,6 +32,7 @@ #include <linux/sched/signal.h> #include <linux/sched/mm.h> #include <linux/sched/stat.h> +#include <linux/wait.h> #include <linux/cpumask.h> #include <linux/smp.h> #include <linux/anon_inodes.h> @@ -3426,6 +3427,7 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu) */ bool kvm_vcpu_block(struct kvm_vcpu *vcpu) { + DEFINE_WAIT_FUNC(vcpu_block_wait, woken_wake_function); struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu); bool waited = false; @@ -3437,13 +3439,11 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu) preempt_enable(); for (;;) { - set_current_state(TASK_INTERRUPTIBLE); - if (kvm_vcpu_check_block(vcpu) < 0) break; waited = true; - schedule(); + wait_woken(&vcpu_block_wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } preempt_disable(); -- 2.38.1.584.g0f3c55d4c2-goog
