cerc-io/lotus
16
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 27 Wiki Activity

fix potential deadlock in View

Browse Source 
As pointed out by magik, it is possible to deadlock if the view callback performs
a blockstore operation while a Lock is pending.
This fixes the issue by optimistically tracking the reference before actually calling
the underlying View and limiting the scope of the lock.
This commit is contained in:
vyzo 2021-07-08 21:18:59 +03:00
parent c0537848b3
commit 60dd97c7fc
1 changed files with 10 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
blockstore/splitstore/splitstore.go
View File

@ -376,19 +376,19 @@ func (s *SplitStore) HashOnRead(enabled bool) {
}
func (s *SplitStore) View(cid cid.Cid, cb func([]byte) error) error {
// optimistically protect the reference so that we can call the underlying View
// without holding hte lock.
// This allows the user callback to call into the blockstore without deadlocking.
s.txnLk.RLock()
defer s.txnLk.RUnlock()
err := s.trackTxnRef(cid)
s.txnLk.RUnlock()
err := s.hot.View(cid, cb)
switch err {
case nil:
err = s.trackTxnRef(cid)
if err != nil {
log.Warnf("error tracking reference to %s: %s", cid, err)
}
return nil
err = s.hot.View(cid, cb)
switch err {
case bstore.ErrNotFound:
if s.debug != nil {
s.mx.Lock()