libgit2: remove deadlock

Some scenarios may lead to deadlocks, specially
in image automation controller.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>
This commit is contained in:
Paulo Gomes 2022-06-16 13:50:14 +01:00
parent 812f6e49dd
commit 09fae634df
No known key found for this signature in database
GPG Key ID: 9995233870E99BEE
1 changed files with 13 additions and 16 deletions

View File

@ -54,6 +54,7 @@ import (
"runtime"
"strings"
"sync"
"sync/atomic"
"time"
"golang.org/x/crypto/ssh"
@ -80,10 +81,12 @@ func registerManagedSSH() error {
}
func sshSmartSubtransportFactory(remote *git2go.Remote, transport *git2go.Transport) (git2go.SmartSubtransport, error) {
var closed int32 = 0
return &sshSmartSubtransport{
transport: transport,
ctx: context.Background(),
logger: logr.Discard(),
transport: transport,
ctx: context.Background(),
logger: logr.Discard(),
closedSessions: &closed,
}, nil
}
@ -109,6 +112,8 @@ type sshSmartSubtransport struct {
stdin io.WriteCloser
stdout io.Reader
closedSessions *int32
con connection
}
@ -117,7 +122,6 @@ type connection struct {
session *ssh.Session
currentStream *sshSmartSubtransportStream
connected bool
m sync.RWMutex
}
func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.SmartServiceAction) (git2go.SmartSubtransportStream, error) {
@ -208,13 +212,11 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
return nil
}
t.con.m.RLock()
if t.con.connected == true {
if t.con.connected {
// The connection is no longer shared across actions, so ensures
// all has been released before starting a new connection.
_ = t.Close()
}
t.con.m.RUnlock()
err = t.createConn(addr, sshConfig)
if err != nil {
@ -251,7 +253,6 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
"recovered from libgit2 ssh smart subtransport panic")
}
}()
var cancel context.CancelFunc
ctx := t.ctx
@ -261,6 +262,7 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
defer cancel()
}
closedAlready := atomic.LoadInt32(t.closedSessions)
for {
select {
case <-ctx.Done():
@ -268,12 +270,9 @@ func (t *sshSmartSubtransport) Action(transportOptionsURL string, action git2go.
return nil
default:
t.con.m.RLock()
if !t.con.connected {
t.con.m.RUnlock()
if atomic.LoadInt32(t.closedSessions) > closedAlready {
return nil
}
t.con.m.RUnlock()
_, err := io.Copy(w, reader)
if err != nil {
@ -311,10 +310,8 @@ func (t *sshSmartSubtransport) createConn(addr string, sshConfig *ssh.ClientConf
return err
}
t.con.m.Lock()
t.con.connected = true
t.con.client = ssh.NewClient(c, chans, reqs)
t.con.m.Unlock()
return nil
}
@ -330,8 +327,6 @@ func (t *sshSmartSubtransport) createConn(addr string, sshConfig *ssh.ClientConf
// SmartSubTransport (i.e. unreleased resources, staled connections).
func (t *sshSmartSubtransport) Close() error {
t.logger.V(logger.TraceLevel).Info("sshSmartSubtransport.Close()")
t.con.m.Lock()
defer t.con.m.Unlock()
t.con.currentStream = nil
if t.con.client != nil && t.stdin != nil {
@ -349,8 +344,10 @@ func (t *sshSmartSubtransport) Close() error {
_ = t.con.client.Close()
t.logger.V(logger.TraceLevel).Info("close client")
}
t.con.client = nil
t.con.connected = false
atomic.AddInt32(t.closedSessions, 1)
return nil
}