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authorTamir Duberstein <tamird@google.com>2020-06-25 14:17:00 -0700
committergVisor bot <gvisor-bot@google.com>2020-06-25 14:18:33 -0700
commit4069461877d843654d18db74a5962b332f1226aa (patch)
tree48affc2bd8c7de9ae5f2cd19307c7ccbb63553b9 /pkg/sentry
parent00ee5abaa70965b1baad996f53d3dc2a17805fcf (diff)
Avoid an allocation in epoll
PiperOrigin-RevId: 318346153
Diffstat (limited to 'pkg/sentry')
-rw-r--r--pkg/sentry/kernel/epoll/epoll.go32
-rw-r--r--pkg/sentry/kernel/epoll/epoll_state.go2
2 files changed, 15 insertions, 19 deletions
diff --git a/pkg/sentry/kernel/epoll/epoll.go b/pkg/sentry/kernel/epoll/epoll.go
index 679ab495d..4c0f1e41f 100644
--- a/pkg/sentry/kernel/epoll/epoll.go
+++ b/pkg/sentry/kernel/epoll/epoll.go
@@ -107,7 +107,7 @@ type EventPoll struct {
// different lock to avoid circular lock acquisition order involving
// the wait queue mutexes and mu. The full order is mu, observed file
// wait queue mutex, then listsMu; this allows listsMu to be acquired
- // when readyCallback is called.
+ // when (*pollEntry).Callback is called.
//
// An entry is always in one of the following lists:
// readyList -- when there's a chance that it's ready to have
@@ -116,7 +116,7 @@ type EventPoll struct {
// readEvents() functions always call the entry's file
// Readiness() function to confirm it's ready.
// waitingList -- when there's no chance that the entry is ready,
- // so it's waiting for the readyCallback to be called
+ // so it's waiting for the (*pollEntry).Callback to be called
// on it before it gets moved to the readyList.
// disabledList -- when the entry is disabled. This happens when
// a one-shot entry gets delivered via readEvents().
@@ -269,23 +269,19 @@ func (e *EventPoll) ReadEvents(max int) []linux.EpollEvent {
return ret
}
-// readyCallback is called when one of the files we're polling becomes ready. It
-// moves said file to the readyList if it's currently in the waiting list.
-type readyCallback struct {
- context *pollEntry
-}
-
// Callback implements waiter.EntryCallback.Callback.
-func (r *readyCallback) Callback(*waiter.Entry) {
- entry := r.context
- e := entry.epoll
+//
+// Callback is called when one of the files we're polling becomes ready. It
+// moves said file to the readyList if it's currently in the waiting list.
+func (p *pollEntry) Callback(*waiter.Entry) {
+ e := p.epoll
e.listsMu.Lock()
- if entry.curList == &e.waitingList {
- e.waitingList.Remove(entry)
- e.readyList.PushBack(entry)
- entry.curList = &e.readyList
+ if p.curList == &e.waitingList {
+ e.waitingList.Remove(p)
+ e.readyList.PushBack(p)
+ p.curList = &e.readyList
e.listsMu.Unlock()
e.Notify(waiter.EventIn)
@@ -312,7 +308,7 @@ func (e *EventPoll) initEntryReadiness(entry *pollEntry) {
// Check if the file happens to already be in a ready state.
ready := f.Readiness(entry.mask) & entry.mask
if ready != 0 {
- (&readyCallback{context: entry}).Callback(&entry.waiter)
+ entry.Callback(&entry.waiter)
}
}
@@ -384,7 +380,7 @@ func (e *EventPoll) AddEntry(id FileIdentifier, flags EntryFlags, mask waiter.Ev
flags: flags,
mask: mask,
}
- entry.waiter.Callback = &readyCallback{context: entry}
+ entry.waiter.Callback = entry
e.files[id] = entry
entry.file = refs.NewWeakRef(id.File, entry)
@@ -407,7 +403,7 @@ func (e *EventPoll) UpdateEntry(id FileIdentifier, flags EntryFlags, mask waiter
}
// Unregister the old mask and remove entry from the list it's in, so
- // readyCallback is guaranteed to not be called on this entry anymore.
+ // (*pollEntry).Callback is guaranteed to not be called on this entry anymore.
entry.id.File.EventUnregister(&entry.waiter)
// Remove entry from whatever list it's in. This ensure that no other
diff --git a/pkg/sentry/kernel/epoll/epoll_state.go b/pkg/sentry/kernel/epoll/epoll_state.go
index 02f9aabfa..7c61e0258 100644
--- a/pkg/sentry/kernel/epoll/epoll_state.go
+++ b/pkg/sentry/kernel/epoll/epoll_state.go
@@ -21,7 +21,7 @@ import (
// afterLoad is invoked by stateify.
func (p *pollEntry) afterLoad() {
- p.waiter.Callback = &readyCallback{context: p}
+ p.waiter.Callback = p
p.file = refs.NewWeakRef(p.id.File, p)
p.id.File.EventRegister(&p.waiter, p.mask)
}