Merge pull request #2006 from TheBlueMatt/2023-02-no-recursive-read-locks

[rust-lightning] / lightning / src / chain / channelmonitor.rs

diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs
index 8b281db6030dba2f681720a91eba819918d20d3f..a664c7c794efe019dd82e909c132c1fd839b9ccf 100644 (file)
--- a/lightning/src/chain/channelmonitor.rs
+++ b/lightning/src/chain/channelmonitor.rs
@@ -60,7 +60,7 @@ use core::{cmp, mem};
 use crate::io::{self, Error};
 use core::convert::TryInto;
 use core::ops::Deref;
-use crate::sync::Mutex;
+use crate::sync::{Mutex, LockTestExt};
 
 /// An update generated by the underlying channel itself which contains some new information the
 /// [`ChannelMonitor`] should be made aware of.
@@ -851,9 +851,13 @@ pub type TransactionOutputs = (Txid, Vec<(u32, TxOut)>);
 
 impl<Signer: WriteableEcdsaChannelSigner> PartialEq for ChannelMonitor<Signer> where Signer: PartialEq {
        fn eq(&self, other: &Self) -> bool {
-               let inner = self.inner.lock().unwrap();
-               let other = other.inner.lock().unwrap();
-               inner.eq(&other)
+               // We need some kind of total lockorder. Absent a better idea, we sort by position in
+               // memory and take locks in that order (assuming that we can't move within memory while a
+               // lock is held).
+               let ord = ((self as *const _) as usize) < ((other as *const _) as usize);
+               let a = if ord { self.inner.unsafe_well_ordered_double_lock_self() } else { other.inner.unsafe_well_ordered_double_lock_self() };
+               let b = if ord { other.inner.unsafe_well_ordered_double_lock_self() } else { self.inner.unsafe_well_ordered_double_lock_self() };
+               a.eq(&b)
        }
 }
 
@@ -4066,7 +4070,10 @@ mod tests {
        fn test_prune_preimages() {
                let secp_ctx = Secp256k1::new();
                let logger = Arc::new(TestLogger::new());
-               let broadcaster = Arc::new(TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new()), blocks: Arc::new(Mutex::new(Vec::new()))});
+               let broadcaster = Arc::new(TestBroadcaster {
+                       txn_broadcasted: Mutex::new(Vec::new()),
+                       blocks: Arc::new(Mutex::new(Vec::new()))
+               });
                let fee_estimator = TestFeeEstimator { sat_per_kw: Mutex::new(253) };
 
                let dummy_key = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());