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Initialize kernel.unimplementedSyscallEmitter with a sync.Once. 

This is initialized lazily on the first unimplemented
syscall. Without the sync.Once, this is racy.

PiperOrigin-RevId: 260971758
This commit is contained in:
Nicolas Lacasse 2019-07-31 11:59:21 -07:00 committed by gVisor bot
parent edcc60b931
commit cf2b2d97d5
1 changed files with 7 additions and 3 deletions
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10
pkg/sentry/kernel/kernel.go
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@ -198,6 +198,10 @@ type Kernel struct {
// the limiter. It may be nil if disabled.
DirentCacheLimiter *fs.DirentCacheLimiter
// unimplementedSyscallEmitterOnce is used in the initialization of
// unimplementedSyscallEmitter.
unimplementedSyscallEmitterOnce sync.Once `state:"nosave"`
// unimplementedSyscallEmitter is used to emit unimplemented syscall
// events. This is initialized lazily on the first unimplemented
// syscall.
@ -1283,7 +1287,7 @@ func (ctx supervisorContext) Value(key interface{}) interface{} {
}
}
// Rate limits for the number of unimplemented syscall evants.
// Rate limits for the number of unimplemented syscall events.
const (
unimplementedSyscallsMaxRate = 100 // events per second
unimplementedSyscallBurst = 1000 // events
@ -1292,9 +1296,9 @@ const (
// EmitUnimplementedEvent emits an UnimplementedSyscall event via the event
// channel.
func (k *Kernel) EmitUnimplementedEvent(ctx context.Context) {
if k.unimplementedSyscallEmitter == nil {
k.unimplementedSyscallEmitterOnce.Do(func() {
k.unimplementedSyscallEmitter = eventchannel.RateLimitedEmitterFrom(eventchannel.DefaultEmitter, unimplementedSyscallsMaxRate, unimplementedSyscallBurst)
}
})
t := TaskFromContext(ctx)
k.unimplementedSyscallEmitter.Emit(&uspb.UnimplementedSyscall{