diff options
Diffstat (limited to 'pkg')
-rw-r--r-- | pkg/abi/linux/linux_abi_autogen_unsafe.go | 12 | ||||
-rw-r--r-- | pkg/sentry/kernel/kernel.go | 5 | ||||
-rw-r--r-- | pkg/sentry/kernel/time/tcpip.go | 131 | ||||
-rw-r--r-- | pkg/tcpip/stack/ndp.go | 140 | ||||
-rw-r--r-- | pkg/tcpip/stack/stack.go | 12 | ||||
-rw-r--r-- | pkg/tcpip/tcpip.go | 27 | ||||
-rw-r--r-- | pkg/tcpip/time_unsafe.go | 30 | ||||
-rw-r--r-- | pkg/tcpip/timer.go | 147 | ||||
-rw-r--r-- | pkg/tcpip/transport/icmp/endpoint.go | 2 | ||||
-rw-r--r-- | pkg/tcpip/transport/packet/endpoint.go | 2 | ||||
-rw-r--r-- | pkg/tcpip/transport/raw/endpoint.go | 2 | ||||
-rw-r--r-- | pkg/tcpip/transport/udp/endpoint.go | 2 |
12 files changed, 371 insertions, 141 deletions
diff --git a/pkg/abi/linux/linux_abi_autogen_unsafe.go b/pkg/abi/linux/linux_abi_autogen_unsafe.go index 6ea96906a..d8cc7aad0 100644 --- a/pkg/abi/linux/linux_abi_autogen_unsafe.go +++ b/pkg/abi/linux/linux_abi_autogen_unsafe.go @@ -135,12 +135,12 @@ func (s *Statx) UnmarshalBytes(src []byte) { // Packed implements marshal.Marshallable.Packed. //go:nosplit func (s *Statx) Packed() bool { - return s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() + return s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() && s.Btime.Packed() } // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe. func (s *Statx) MarshalUnsafe(dst []byte) { - if s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() && s.Btime.Packed() { + if s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() { safecopy.CopyIn(dst, unsafe.Pointer(s)) } else { s.MarshalBytes(dst) @@ -159,7 +159,7 @@ func (s *Statx) UnmarshalUnsafe(src []byte) { // CopyOutN implements marshal.Marshallable.CopyOutN. //go:nosplit func (s *Statx) CopyOutN(task marshal.Task, addr usermem.Addr, limit int) (int, error) { - if !s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() { + if !s.Mtime.Packed() && s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() { // Type Statx doesn't have a packed layout in memory, fall back to MarshalBytes. buf := task.CopyScratchBuffer(s.SizeBytes()) // escapes: okay. s.MarshalBytes(buf) // escapes: fallback. @@ -808,7 +808,7 @@ func (i *IPTIP) MarshalUnsafe(dst []byte) { // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe. func (i *IPTIP) UnmarshalUnsafe(src []byte) { - if i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() { + if i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed() { safecopy.CopyOut(unsafe.Pointer(i), src) } else { i.UnmarshalBytes(src) @@ -848,7 +848,7 @@ func (i *IPTIP) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) { // CopyIn implements marshal.Marshallable.CopyIn. //go:nosplit func (i *IPTIP) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) { - if !i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() { + if !i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() { // Type IPTIP doesn't have a packed layout in memory, fall back to UnmarshalBytes. buf := task.CopyScratchBuffer(i.SizeBytes()) // escapes: okay. length, err := task.CopyInBytes(addr, buf) // escapes: okay. @@ -874,7 +874,7 @@ func (i *IPTIP) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) { // WriteTo implements io.WriterTo.WriteTo. func (i *IPTIP) WriteTo(w io.Writer) (int64, error) { - if !i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() { + if !i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() { // Type IPTIP doesn't have a packed layout in memory, fall back to MarshalBytes. buf := make([]byte, i.SizeBytes()) i.MarshalBytes(buf) diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go index 240cd6fe0..15dae0f5b 100644 --- a/pkg/sentry/kernel/kernel.go +++ b/pkg/sentry/kernel/kernel.go @@ -1469,6 +1469,11 @@ func (k *Kernel) NowMonotonic() int64 { return now } +// AfterFunc implements tcpip.Clock.AfterFunc. +func (k *Kernel) AfterFunc(d time.Duration, f func()) tcpip.Timer { + return ktime.TcpipAfterFunc(k.realtimeClock, d, f) +} + // SetMemoryFile sets Kernel.mf. SetMemoryFile must be called before Init or // LoadFrom. func (k *Kernel) SetMemoryFile(mf *pgalloc.MemoryFile) { diff --git a/pkg/sentry/kernel/time/tcpip.go b/pkg/sentry/kernel/time/tcpip.go new file mode 100644 index 000000000..c4474c0cf --- /dev/null +++ b/pkg/sentry/kernel/time/tcpip.go @@ -0,0 +1,131 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package time + +import ( + "sync" + "time" +) + +// TcpipAfterFunc waits for duration to elapse according to clock then runs fn. +// The timer is started immediately and will fire exactly once. +func TcpipAfterFunc(clock Clock, duration time.Duration, fn func()) *TcpipTimer { + timer := &TcpipTimer{ + clock: clock, + } + timer.notifier = functionNotifier{ + fn: func() { + // tcpip.Timer.Stop() explicitly states that the function is called in a + // separate goroutine that Stop() does not synchronize with. + // Timer.Destroy() synchronizes with calls to TimerListener.Notify(). + // This is semantically meaningful because, in the former case, it's + // legal to call tcpip.Timer.Stop() while holding locks that may also be + // taken by the function, but this isn't so in the latter case. Most + // immediately, Timer calls TimerListener.Notify() while holding + // Timer.mu. A deadlock occurs without spawning a goroutine: + // T1: (Timer expires) + // => Timer.Tick() <- Timer.mu.Lock() called + // => TimerListener.Notify() + // => Timer.Stop() + // => Timer.Destroy() <- Timer.mu.Lock() called, deadlock! + // + // Spawning a goroutine avoids the deadlock: + // T1: (Timer expires) + // => Timer.Tick() <- Timer.mu.Lock() called + // => TimerListener.Notify() <- Launches T2 + // T2: + // => Timer.Stop() + // => Timer.Destroy() <- Timer.mu.Lock() called, blocks + // T1: + // => (returns) <- Timer.mu.Unlock() called + // T2: + // => (continues) <- No deadlock! + go func() { + timer.Stop() + fn() + }() + }, + } + timer.Reset(duration) + return timer +} + +// TcpipTimer is a resettable timer with variable duration expirations. +// Implements tcpip.Timer, which does not define a Destroy method; instead, all +// resources are released after timer expiration and calls to Timer.Stop. +// +// Must be created by AfterFunc. +type TcpipTimer struct { + // clock is the time source. clock is immutable. + clock Clock + + // notifier is called when the Timer expires. notifier is immutable. + notifier functionNotifier + + // mu protects t. + mu sync.Mutex + + // t stores the latest running Timer. This is replaced whenever Reset is + // called since Timer cannot be restarted once it has been Destroyed by Stop. + // + // This field is nil iff Stop has been called. + t *Timer +} + +// Stop implements tcpip.Timer.Stop. +func (r *TcpipTimer) Stop() bool { + r.mu.Lock() + defer r.mu.Unlock() + + if r.t == nil { + return false + } + _, lastSetting := r.t.Swap(Setting{}) + r.t.Destroy() + r.t = nil + return lastSetting.Enabled +} + +// Reset implements tcpip.Timer.Reset. +func (r *TcpipTimer) Reset(d time.Duration) { + r.mu.Lock() + defer r.mu.Unlock() + + if r.t == nil { + r.t = NewTimer(r.clock, &r.notifier) + } + + r.t.Swap(Setting{ + Enabled: true, + Period: 0, + Next: r.clock.Now().Add(d), + }) +} + +// functionNotifier is a TimerListener that runs a function. +// +// functionNotifier cannot be saved or loaded. +type functionNotifier struct { + fn func() +} + +// Notify implements ktime.TimerListener.Notify. +func (f *functionNotifier) Notify(uint64, Setting) (Setting, bool) { + f.fn() + return Setting{}, false +} + +// Destroy implements ktime.TimerListener.Destroy. +func (f *functionNotifier) Destroy() {} diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go index e28c23d66..9dce11a97 100644 --- a/pkg/tcpip/stack/ndp.go +++ b/pkg/tcpip/stack/ndp.go @@ -469,7 +469,7 @@ type ndpState struct { rtrSolicit struct { // The timer used to send the next router solicitation message. - timer *time.Timer + timer tcpip.Timer // Used to let the Router Solicitation timer know that it has been stopped. // @@ -503,7 +503,7 @@ type ndpState struct { // to the DAD goroutine that DAD should stop. type dadState struct { // The DAD timer to send the next NS message, or resolve the address. - timer *time.Timer + timer tcpip.Timer // Used to let the DAD timer know that it has been stopped. // @@ -515,38 +515,38 @@ type dadState struct { // defaultRouterState holds data associated with a default router discovered by // a Router Advertisement (RA). type defaultRouterState struct { - // Timer to invalidate the default router. + // Job to invalidate the default router. // // Must not be nil. - invalidationTimer *tcpip.CancellableTimer + invalidationJob *tcpip.Job } // onLinkPrefixState holds data associated with an on-link prefix discovered by // a Router Advertisement's Prefix Information option (PI) when the NDP // configurations was configured to do so. type onLinkPrefixState struct { - // Timer to invalidate the on-link prefix. + // Job to invalidate the on-link prefix. // // Must not be nil. - invalidationTimer *tcpip.CancellableTimer + invalidationJob *tcpip.Job } // tempSLAACAddrState holds state associated with a temporary SLAAC address. type tempSLAACAddrState struct { - // Timer to deprecate the temporary SLAAC address. + // Job to deprecate the temporary SLAAC address. // // Must not be nil. - deprecationTimer *tcpip.CancellableTimer + deprecationJob *tcpip.Job - // Timer to invalidate the temporary SLAAC address. + // Job to invalidate the temporary SLAAC address. // // Must not be nil. - invalidationTimer *tcpip.CancellableTimer + invalidationJob *tcpip.Job - // Timer to regenerate the temporary SLAAC address. + // Job to regenerate the temporary SLAAC address. // // Must not be nil. - regenTimer *tcpip.CancellableTimer + regenJob *tcpip.Job createdAt time.Time @@ -561,15 +561,15 @@ type tempSLAACAddrState struct { // slaacPrefixState holds state associated with a SLAAC prefix. type slaacPrefixState struct { - // Timer to deprecate the prefix. + // Job to deprecate the prefix. // // Must not be nil. - deprecationTimer *tcpip.CancellableTimer + deprecationJob *tcpip.Job - // Timer to invalidate the prefix. + // Job to invalidate the prefix. // // Must not be nil. - invalidationTimer *tcpip.CancellableTimer + invalidationJob *tcpip.Job // Nonzero only when the address is not valid forever. validUntil time.Time @@ -651,12 +651,12 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref } var done bool - var timer *time.Timer + var timer tcpip.Timer // We initially start a timer to fire immediately because some of the DAD work // cannot be done while holding the NIC's lock. This is effectively the same // as starting a goroutine but we use a timer that fires immediately so we can // reset it for the next DAD iteration. - timer = time.AfterFunc(0, func() { + timer = ndp.nic.stack.Clock().AfterFunc(0, func() { ndp.nic.mu.Lock() defer ndp.nic.mu.Unlock() @@ -871,9 +871,9 @@ func (ndp *ndpState) handleRA(ip tcpip.Address, ra header.NDPRouterAdvert) { case ok && rl != 0: // This is an already discovered default router. Update - // the invalidation timer. - rtr.invalidationTimer.StopLocked() - rtr.invalidationTimer.Reset(rl) + // the invalidation job. + rtr.invalidationJob.Cancel() + rtr.invalidationJob.Schedule(rl) ndp.defaultRouters[ip] = rtr case ok && rl == 0: @@ -950,7 +950,7 @@ func (ndp *ndpState) invalidateDefaultRouter(ip tcpip.Address) { return } - rtr.invalidationTimer.StopLocked() + rtr.invalidationJob.Cancel() delete(ndp.defaultRouters, ip) // Let the integrator know a discovered default router is invalidated. @@ -979,12 +979,12 @@ func (ndp *ndpState) rememberDefaultRouter(ip tcpip.Address, rl time.Duration) { } state := defaultRouterState{ - invalidationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + invalidationJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { ndp.invalidateDefaultRouter(ip) }), } - state.invalidationTimer.Reset(rl) + state.invalidationJob.Schedule(rl) ndp.defaultRouters[ip] = state } @@ -1009,13 +1009,13 @@ func (ndp *ndpState) rememberOnLinkPrefix(prefix tcpip.Subnet, l time.Duration) } state := onLinkPrefixState{ - invalidationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + invalidationJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { ndp.invalidateOnLinkPrefix(prefix) }), } if l < header.NDPInfiniteLifetime { - state.invalidationTimer.Reset(l) + state.invalidationJob.Schedule(l) } ndp.onLinkPrefixes[prefix] = state @@ -1033,7 +1033,7 @@ func (ndp *ndpState) invalidateOnLinkPrefix(prefix tcpip.Subnet) { return } - s.invalidationTimer.StopLocked() + s.invalidationJob.Cancel() delete(ndp.onLinkPrefixes, prefix) // Let the integrator know a discovered on-link prefix is invalidated. @@ -1082,14 +1082,14 @@ func (ndp *ndpState) handleOnLinkPrefixInformation(pi header.NDPPrefixInformatio // This is an already discovered on-link prefix with a // new non-zero valid lifetime. // - // Update the invalidation timer. + // Update the invalidation job. - prefixState.invalidationTimer.StopLocked() + prefixState.invalidationJob.Cancel() if vl < header.NDPInfiniteLifetime { - // Prefix is valid for a finite lifetime, reset the timer to expire after + // Prefix is valid for a finite lifetime, schedule the job to execute after // the new valid lifetime. - prefixState.invalidationTimer.Reset(vl) + prefixState.invalidationJob.Schedule(vl) } ndp.onLinkPrefixes[prefix] = prefixState @@ -1154,7 +1154,7 @@ func (ndp *ndpState) doSLAAC(prefix tcpip.Subnet, pl, vl time.Duration) { } state := slaacPrefixState{ - deprecationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + deprecationJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { state, ok := ndp.slaacPrefixes[prefix] if !ok { panic(fmt.Sprintf("ndp: must have a slaacPrefixes entry for the deprecated SLAAC prefix %s", prefix)) @@ -1162,7 +1162,7 @@ func (ndp *ndpState) doSLAAC(prefix tcpip.Subnet, pl, vl time.Duration) { ndp.deprecateSLAACAddress(state.stableAddr.ref) }), - invalidationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + invalidationJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { state, ok := ndp.slaacPrefixes[prefix] if !ok { panic(fmt.Sprintf("ndp: must have a slaacPrefixes entry for the invalidated SLAAC prefix %s", prefix)) @@ -1184,19 +1184,19 @@ func (ndp *ndpState) doSLAAC(prefix tcpip.Subnet, pl, vl time.Duration) { if !ndp.generateSLAACAddr(prefix, &state) { // We were unable to generate an address for the prefix, we do not nothing - // further as there is no reason to maintain state or timers for a prefix we + // further as there is no reason to maintain state or jobs for a prefix we // do not have an address for. return } - // Setup the initial timers to deprecate and invalidate prefix. + // Setup the initial jobs to deprecate and invalidate prefix. if pl < header.NDPInfiniteLifetime && pl != 0 { - state.deprecationTimer.Reset(pl) + state.deprecationJob.Schedule(pl) } if vl < header.NDPInfiniteLifetime { - state.invalidationTimer.Reset(vl) + state.invalidationJob.Schedule(vl) state.validUntil = now.Add(vl) } @@ -1428,7 +1428,7 @@ func (ndp *ndpState) generateTempSLAACAddr(prefix tcpip.Subnet, prefixState *sla } state := tempSLAACAddrState{ - deprecationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + deprecationJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { prefixState, ok := ndp.slaacPrefixes[prefix] if !ok { panic(fmt.Sprintf("ndp: must have a slaacPrefixes entry for %s to deprecate temporary address %s", prefix, generatedAddr)) @@ -1441,7 +1441,7 @@ func (ndp *ndpState) generateTempSLAACAddr(prefix tcpip.Subnet, prefixState *sla ndp.deprecateSLAACAddress(tempAddrState.ref) }), - invalidationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + invalidationJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { prefixState, ok := ndp.slaacPrefixes[prefix] if !ok { panic(fmt.Sprintf("ndp: must have a slaacPrefixes entry for %s to invalidate temporary address %s", prefix, generatedAddr)) @@ -1454,7 +1454,7 @@ func (ndp *ndpState) generateTempSLAACAddr(prefix tcpip.Subnet, prefixState *sla ndp.invalidateTempSLAACAddr(prefixState.tempAddrs, generatedAddr.Address, tempAddrState) }), - regenTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { + regenJob: ndp.nic.stack.newJob(&ndp.nic.mu, func() { prefixState, ok := ndp.slaacPrefixes[prefix] if !ok { panic(fmt.Sprintf("ndp: must have a slaacPrefixes entry for %s to regenerate temporary address after %s", prefix, generatedAddr)) @@ -1481,9 +1481,9 @@ func (ndp *ndpState) generateTempSLAACAddr(prefix tcpip.Subnet, prefixState *sla ref: ref, } - state.deprecationTimer.Reset(pl) - state.invalidationTimer.Reset(vl) - state.regenTimer.Reset(pl - ndp.configs.RegenAdvanceDuration) + state.deprecationJob.Schedule(pl) + state.invalidationJob.Schedule(vl) + state.regenJob.Schedule(pl - ndp.configs.RegenAdvanceDuration) prefixState.generationAttempts++ prefixState.tempAddrs[generatedAddr.Address] = state @@ -1518,16 +1518,16 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat prefixState.stableAddr.ref.deprecated = false } - // If prefix was preferred for some finite lifetime before, stop the - // deprecation timer so it can be reset. - prefixState.deprecationTimer.StopLocked() + // If prefix was preferred for some finite lifetime before, cancel the + // deprecation job so it can be reset. + prefixState.deprecationJob.Cancel() now := time.Now() - // Reset the deprecation timer if prefix has a finite preferred lifetime. + // Schedule the deprecation job if prefix has a finite preferred lifetime. if pl < header.NDPInfiniteLifetime { if !deprecated { - prefixState.deprecationTimer.Reset(pl) + prefixState.deprecationJob.Schedule(pl) } prefixState.preferredUntil = now.Add(pl) } else { @@ -1546,9 +1546,9 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat // 3) Otherwise, reset the valid lifetime of the prefix to 2 hours. if vl >= header.NDPInfiniteLifetime { - // Handle the infinite valid lifetime separately as we do not keep a timer - // in this case. - prefixState.invalidationTimer.StopLocked() + // Handle the infinite valid lifetime separately as we do not schedule a + // job in this case. + prefixState.invalidationJob.Cancel() prefixState.validUntil = time.Time{} } else { var effectiveVl time.Duration @@ -1569,8 +1569,8 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat } if effectiveVl != 0 { - prefixState.invalidationTimer.StopLocked() - prefixState.invalidationTimer.Reset(effectiveVl) + prefixState.invalidationJob.Cancel() + prefixState.invalidationJob.Schedule(effectiveVl) prefixState.validUntil = now.Add(effectiveVl) } } @@ -1582,7 +1582,7 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat } // Note, we do not need to update the entries in the temporary address map - // after updating the timers because the timers are held as pointers. + // after updating the jobs because the jobs are held as pointers. var regenForAddr tcpip.Address allAddressesRegenerated := true for tempAddr, tempAddrState := range prefixState.tempAddrs { @@ -1596,14 +1596,14 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat } // If the address is no longer valid, invalidate it immediately. Otherwise, - // reset the invalidation timer. + // reset the invalidation job. newValidLifetime := validUntil.Sub(now) if newValidLifetime <= 0 { ndp.invalidateTempSLAACAddr(prefixState.tempAddrs, tempAddr, tempAddrState) continue } - tempAddrState.invalidationTimer.StopLocked() - tempAddrState.invalidationTimer.Reset(newValidLifetime) + tempAddrState.invalidationJob.Cancel() + tempAddrState.invalidationJob.Schedule(newValidLifetime) // As per RFC 4941 section 3.3 step 4, the preferred lifetime of a temporary // address is the lower of the preferred lifetime of the stable address or @@ -1616,17 +1616,17 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat } // If the address is no longer preferred, deprecate it immediately. - // Otherwise, reset the deprecation timer. + // Otherwise, schedule the deprecation job again. newPreferredLifetime := preferredUntil.Sub(now) - tempAddrState.deprecationTimer.StopLocked() + tempAddrState.deprecationJob.Cancel() if newPreferredLifetime <= 0 { ndp.deprecateSLAACAddress(tempAddrState.ref) } else { tempAddrState.ref.deprecated = false - tempAddrState.deprecationTimer.Reset(newPreferredLifetime) + tempAddrState.deprecationJob.Schedule(newPreferredLifetime) } - tempAddrState.regenTimer.StopLocked() + tempAddrState.regenJob.Cancel() if tempAddrState.regenerated { } else { allAddressesRegenerated = false @@ -1637,7 +1637,7 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat // immediately after we finish iterating over the temporary addresses. regenForAddr = tempAddr } else { - tempAddrState.regenTimer.Reset(newPreferredLifetime - ndp.configs.RegenAdvanceDuration) + tempAddrState.regenJob.Schedule(newPreferredLifetime - ndp.configs.RegenAdvanceDuration) } } } @@ -1717,7 +1717,7 @@ func (ndp *ndpState) cleanupSLAACAddrResourcesAndNotify(addr tcpip.AddressWithPr ndp.cleanupSLAACPrefixResources(prefix, state) } -// cleanupSLAACPrefixResources cleansup a SLAAC prefix's timers and entry. +// cleanupSLAACPrefixResources cleans up a SLAAC prefix's jobs and entry. // // Panics if the SLAAC prefix is not known. // @@ -1729,8 +1729,8 @@ func (ndp *ndpState) cleanupSLAACPrefixResources(prefix tcpip.Subnet, state slaa } state.stableAddr.ref = nil - state.deprecationTimer.StopLocked() - state.invalidationTimer.StopLocked() + state.deprecationJob.Cancel() + state.invalidationJob.Cancel() delete(ndp.slaacPrefixes, prefix) } @@ -1775,13 +1775,13 @@ func (ndp *ndpState) cleanupTempSLAACAddrResourcesAndNotify(addr tcpip.AddressWi } // cleanupTempSLAACAddrResourcesAndNotify cleans up a temporary SLAAC address's -// timers and entry. +// jobs and entry. // // The NIC that ndp belongs to MUST be locked. func (ndp *ndpState) cleanupTempSLAACAddrResources(tempAddrs map[tcpip.Address]tempSLAACAddrState, tempAddr tcpip.Address, tempAddrState tempSLAACAddrState) { - tempAddrState.deprecationTimer.StopLocked() - tempAddrState.invalidationTimer.StopLocked() - tempAddrState.regenTimer.StopLocked() + tempAddrState.deprecationJob.Cancel() + tempAddrState.invalidationJob.Cancel() + tempAddrState.regenJob.Cancel() delete(tempAddrs, tempAddr) } @@ -1860,7 +1860,7 @@ func (ndp *ndpState) startSolicitingRouters() { var done bool ndp.rtrSolicit.done = &done - ndp.rtrSolicit.timer = time.AfterFunc(delay, func() { + ndp.rtrSolicit.timer = ndp.nic.stack.Clock().AfterFunc(delay, func() { ndp.nic.mu.Lock() if done { // If we reach this point, it means that the RS timer fired after another diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go index 2b7ece851..a6faa22c2 100644 --- a/pkg/tcpip/stack/stack.go +++ b/pkg/tcpip/stack/stack.go @@ -728,6 +728,11 @@ func New(opts Options) *Stack { return s } +// newJob returns a tcpip.Job using the Stack clock. +func (s *Stack) newJob(l sync.Locker, f func()) *tcpip.Job { + return tcpip.NewJob(s.clock, l, f) +} + // UniqueID returns a unique identifier. func (s *Stack) UniqueID() uint64 { return s.uniqueIDGenerator.UniqueID() @@ -801,9 +806,10 @@ func (s *Stack) SetTransportProtocolHandler(p tcpip.TransportProtocolNumber, h f } } -// NowNanoseconds implements tcpip.Clock.NowNanoseconds. -func (s *Stack) NowNanoseconds() int64 { - return s.clock.NowNanoseconds() +// Clock returns the Stack's clock for retrieving the current time and +// scheduling work. +func (s *Stack) Clock() tcpip.Clock { + return s.clock } // Stats returns a mutable copy of the current stats. diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go index ff14a3b3c..21aafb0a2 100644 --- a/pkg/tcpip/tcpip.go +++ b/pkg/tcpip/tcpip.go @@ -192,7 +192,7 @@ func (e ErrSaveRejection) Error() string { return "save rejected due to unsupported networking state: " + e.Err.Error() } -// A Clock provides the current time. +// A Clock provides the current time and schedules work for execution. // // Times returned by a Clock should always be used for application-visible // time. Only monotonic times should be used for netstack internal timekeeping. @@ -203,6 +203,31 @@ type Clock interface { // NowMonotonic returns a monotonic time value. NowMonotonic() int64 + + // AfterFunc waits for the duration to elapse and then calls f in its own + // goroutine. It returns a Timer that can be used to cancel the call using + // its Stop method. + AfterFunc(d time.Duration, f func()) Timer +} + +// Timer represents a single event. A Timer must be created with +// Clock.AfterFunc. +type Timer interface { + // Stop prevents the Timer from firing. It returns true if the call stops the + // timer, false if the timer has already expired or been stopped. + // + // If Stop returns false, then the timer has already expired and the function + // f of Clock.AfterFunc(d, f) has been started in its own goroutine; Stop + // does not wait for f to complete before returning. If the caller needs to + // know whether f is completed, it must coordinate with f explicitly. + Stop() bool + + // Reset changes the timer to expire after duration d. + // + // Reset should be invoked only on stopped or expired timers. If the timer is + // known to have expired, Reset can be used directly. Otherwise, the caller + // must coordinate with the function f of Clock.AfterFunc(d, f). + Reset(d time.Duration) } // Address is a byte slice cast as a string that represents the address of a diff --git a/pkg/tcpip/time_unsafe.go b/pkg/tcpip/time_unsafe.go index 7f172f978..f32d58091 100644 --- a/pkg/tcpip/time_unsafe.go +++ b/pkg/tcpip/time_unsafe.go @@ -20,7 +20,7 @@ package tcpip import ( - _ "time" // Used with go:linkname. + "time" // Used with go:linkname. _ "unsafe" // Required for go:linkname. ) @@ -45,3 +45,31 @@ func (*StdClock) NowMonotonic() int64 { _, _, mono := now() return mono } + +// AfterFunc implements Clock.AfterFunc. +func (*StdClock) AfterFunc(d time.Duration, f func()) Timer { + return &stdTimer{ + t: time.AfterFunc(d, f), + } +} + +type stdTimer struct { + t *time.Timer +} + +var _ Timer = (*stdTimer)(nil) + +// Stop implements Timer.Stop. +func (st *stdTimer) Stop() bool { + return st.t.Stop() +} + +// Reset implements Timer.Reset. +func (st *stdTimer) Reset(d time.Duration) { + st.t.Reset(d) +} + +// NewStdTimer returns a Timer implemented with the time package. +func NewStdTimer(t *time.Timer) Timer { + return &stdTimer{t: t} +} diff --git a/pkg/tcpip/timer.go b/pkg/tcpip/timer.go index 5554c573f..f1dd7c310 100644 --- a/pkg/tcpip/timer.go +++ b/pkg/tcpip/timer.go @@ -20,50 +20,49 @@ import ( "gvisor.dev/gvisor/pkg/sync" ) -// cancellableTimerInstance is a specific instance of CancellableTimer. +// jobInstance is a specific instance of Job. // -// Different instances are created each time CancellableTimer is Reset so each -// timer has its own earlyReturn signal. This is to address a bug when a -// CancellableTimer is stopped and reset in quick succession resulting in a -// timer instance's earlyReturn signal being affected or seen by another timer -// instance. +// Different instances are created each time Job is scheduled so each timer has +// its own earlyReturn signal. This is to address a bug when a Job is stopped +// and reset in quick succession resulting in a timer instance's earlyReturn +// signal being affected or seen by another timer instance. // // Consider the following sceneario where timer instances share a common // earlyReturn signal (T1 creates, stops and resets a Cancellable timer under a // lock L; T2, T3, T4 and T5 are goroutines that handle the first (A), second // (B), third (C), and fourth (D) instance of the timer firing, respectively): // T1: Obtain L -// T1: Create a new CancellableTimer w/ lock L (create instance A) +// T1: Create a new Job w/ lock L (create instance A) // T2: instance A fires, blocked trying to obtain L. // T1: Attempt to stop instance A (set earlyReturn = true) -// T1: Reset timer (create instance B) +// T1: Schedule timer (create instance B) // T3: instance B fires, blocked trying to obtain L. // T1: Attempt to stop instance B (set earlyReturn = true) -// T1: Reset timer (create instance C) +// T1: Schedule timer (create instance C) // T4: instance C fires, blocked trying to obtain L. // T1: Attempt to stop instance C (set earlyReturn = true) -// T1: Reset timer (create instance D) +// T1: Schedule timer (create instance D) // T5: instance D fires, blocked trying to obtain L. // T1: Release L // -// Now that T1 has released L, any of the 4 timer instances can take L and check -// earlyReturn. If the timers simply check earlyReturn and then do nothing -// further, then instance D will never early return even though it was not -// requested to stop. If the timers reset earlyReturn before early returning, -// then all but one of the timers will do work when only one was expected to. -// If CancellableTimer resets earlyReturn when resetting, then all the timers +// Now that T1 has released L, any of the 4 timer instances can take L and +// check earlyReturn. If the timers simply check earlyReturn and then do +// nothing further, then instance D will never early return even though it was +// not requested to stop. If the timers reset earlyReturn before early +// returning, then all but one of the timers will do work when only one was +// expected to. If Job resets earlyReturn when resetting, then all the timers // will fire (again, when only one was expected to). // // To address the above concerns the simplest solution was to give each timer // its own earlyReturn signal. -type cancellableTimerInstance struct { - timer *time.Timer +type jobInstance struct { + timer Timer // Used to inform the timer to early return when it gets stopped while the // lock the timer tries to obtain when fired is held (T1 is a goroutine that // tries to cancel the timer and T2 is the goroutine that handles the timer // firing): - // T1: Obtain the lock, then call StopLocked() + // T1: Obtain the lock, then call Cancel() // T2: timer fires, and gets blocked on obtaining the lock // T1: Releases lock // T2: Obtains lock does unintended work @@ -74,29 +73,33 @@ type cancellableTimerInstance struct { earlyReturn *bool } -// stop stops the timer instance t from firing if it hasn't fired already. If it +// stop stops the job instance j from firing if it hasn't fired already. If it // has fired and is blocked at obtaining the lock, earlyReturn will be set to // true so that it will early return when it obtains the lock. -func (t *cancellableTimerInstance) stop() { - if t.timer != nil { - t.timer.Stop() - *t.earlyReturn = true +func (j *jobInstance) stop() { + if j.timer != nil { + j.timer.Stop() + *j.earlyReturn = true } } -// CancellableTimer is a timer that does some work and can be safely cancelled -// when it fires at the same time some "related work" is being done. +// Job represents some work that can be scheduled for execution. The work can +// be safely cancelled when it fires at the same time some "related work" is +// being done. // // The term "related work" is defined as some work that needs to be done while // holding some lock that the timer must also hold while doing some work. // -// Note, it is not safe to copy a CancellableTimer as its timer instance creates -// a closure over the address of the CancellableTimer. -type CancellableTimer struct { +// Note, it is not safe to copy a Job as its timer instance creates +// a closure over the address of the Job. +type Job struct { _ sync.NoCopy + // The clock used to schedule the backing timer + clock Clock + // The active instance of a cancellable timer. - instance cancellableTimerInstance + instance jobInstance // locker is the lock taken by the timer immediately after it fires and must // be held when attempting to stop the timer. @@ -113,59 +116,91 @@ type CancellableTimer struct { fn func() } -// StopLocked prevents the Timer from firing if it has not fired already. +// Cancel prevents the Job from executing if it has not executed already. // -// If the timer is blocked on obtaining the t.locker lock when StopLocked is -// called, it will early return instead of calling t.fn. +// Cancel requires appropriate locking to be in place for any resources managed +// by the Job. If the Job is blocked on obtaining the lock when Cancel is +// called, it will early return. // // Note, t will be modified. // -// t.locker MUST be locked. -func (t *CancellableTimer) StopLocked() { - t.instance.stop() +// j.locker MUST be locked. +func (j *Job) Cancel() { + j.instance.stop() // Nothing to do with the stopped instance anymore. - t.instance = cancellableTimerInstance{} + j.instance = jobInstance{} } -// Reset changes the timer to expire after duration d. +// Schedule schedules the Job for execution after duration d. This can be +// called on cancelled or completed Jobs to schedule them again. // -// Note, t will be modified. +// Schedule should be invoked only on unscheduled, cancelled, or completed +// Jobs. To be safe, callers should always call Cancel before calling Schedule. // -// Reset should only be called on stopped or expired timers. To be safe, callers -// should always call StopLocked before calling Reset. -func (t *CancellableTimer) Reset(d time.Duration) { +// Note, j will be modified. +func (j *Job) Schedule(d time.Duration) { // Create a new instance. earlyReturn := false // Capture the locker so that updating the timer does not cause a data race // when a timer fires and tries to obtain the lock (read the timer's locker). - locker := t.locker - t.instance = cancellableTimerInstance{ - timer: time.AfterFunc(d, func() { + locker := j.locker + j.instance = jobInstance{ + timer: j.clock.AfterFunc(d, func() { locker.Lock() defer locker.Unlock() if earlyReturn { // If we reach this point, it means that the timer fired while another - // goroutine called StopLocked while it had the lock. Simply return - // here and do nothing further. + // goroutine called Cancel while it had the lock. Simply return here + // and do nothing further. earlyReturn = false return } - t.fn() + j.fn() }), earlyReturn: &earlyReturn, } } -// NewCancellableTimer returns an unscheduled CancellableTimer with the given -// locker and fn. -// -// fn MUST NOT attempt to lock locker. -// -// Callers must call Reset to schedule the timer to fire. -func NewCancellableTimer(locker sync.Locker, fn func()) *CancellableTimer { - return &CancellableTimer{locker: locker, fn: fn} +// NewJob returns a new Job that can be used to schedule f to run in its own +// gorountine. l will be locked before calling f then unlocked after f returns. +// +// var clock tcpip.StdClock +// var mu sync.Mutex +// message := "foo" +// job := tcpip.NewJob(&clock, &mu, func() { +// fmt.Println(message) +// }) +// job.Schedule(time.Second) +// +// mu.Lock() +// message = "bar" +// mu.Unlock() +// +// // Output: bar +// +// f MUST NOT attempt to lock l. +// +// l MUST be locked prior to calling the returned job's Cancel(). +// +// var clock tcpip.StdClock +// var mu sync.Mutex +// message := "foo" +// job := tcpip.NewJob(&clock, &mu, func() { +// fmt.Println(message) +// }) +// job.Schedule(time.Second) +// +// mu.Lock() +// job.Cancel() +// mu.Unlock() +func NewJob(c Clock, l sync.Locker, f func()) *Job { + return &Job{ + clock: c, + locker: l, + fn: f, + } } diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go index 678f4e016..4612be4e7 100644 --- a/pkg/tcpip/transport/icmp/endpoint.go +++ b/pkg/tcpip/transport/icmp/endpoint.go @@ -797,7 +797,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, pk e.rcvList.PushBack(packet) e.rcvBufSize += packet.data.Size() - packet.timestamp = e.stack.NowNanoseconds() + packet.timestamp = e.stack.Clock().NowNanoseconds() e.rcvMu.Unlock() e.stats.PacketsReceived.Increment() diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go index 8f167391f..0e46e6355 100644 --- a/pkg/tcpip/transport/packet/endpoint.go +++ b/pkg/tcpip/transport/packet/endpoint.go @@ -499,7 +499,7 @@ func (ep *endpoint) HandlePacket(nicID tcpip.NICID, localAddr tcpip.LinkAddress, combinedVV.Append(pkt.Data) packet.data = combinedVV } - packet.timestampNS = ep.stack.NowNanoseconds() + packet.timestampNS = ep.stack.Clock().NowNanoseconds() ep.rcvList.PushBack(&packet) ep.rcvBufSize += packet.data.Size() diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go index aefe0e2b2..f85a68554 100644 --- a/pkg/tcpip/transport/raw/endpoint.go +++ b/pkg/tcpip/transport/raw/endpoint.go @@ -700,7 +700,7 @@ func (e *endpoint) HandlePacket(route *stack.Route, pkt *stack.PacketBuffer) { } combinedVV.Append(pkt.Data) packet.data = combinedVV - packet.timestampNS = e.stack.NowNanoseconds() + packet.timestampNS = e.stack.Clock().NowNanoseconds() e.rcvList.PushBack(packet) e.rcvBufSize += packet.data.Size() diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go index a14643ae8..6e692da07 100644 --- a/pkg/tcpip/transport/udp/endpoint.go +++ b/pkg/tcpip/transport/udp/endpoint.go @@ -1451,7 +1451,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, pk packet.tos, _ = header.IPv6(pkt.NetworkHeader).TOS() } - packet.timestamp = e.stack.NowNanoseconds() + packet.timestamp = e.stack.Clock().NowNanoseconds() e.rcvMu.Unlock() |