summaryrefslogtreecommitdiff
path: root/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch
diff options
context:
space:
mode:
Diffstat (limited to 'system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch')
-rw-r--r--system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch137
1 files changed, 137 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch b/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch
new file mode 100644
index 0000000000..b0a8e011ee
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch
@@ -0,0 +1,137 @@
+From 0972f3e46001e9b3192786033663ef4ee423f8be Mon Sep 17 00:00:00 2001
+From: Jonathan Davies <jonathan.davies@citrix.com>
+Date: Thu, 23 Mar 2017 14:28:16 +0000
+Subject: [PATCH 11/15] oxenstored: blame the connection that caused a
+ transaction conflict
+
+Blame each connection found to have made a commit that would cause this
+transaction to fail. Each blamed connection is penalised by having its
+conflict-credit decremented.
+
+Note the change in semantics for the replay function: we no longer stop after
+finding the first operation that can't be replayed. This allows us to identify
+all operations that conflicted with this transaction, not just the one that
+conflicted first.
+
+Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+v1 Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+
+Changes since v1:
+ * use correct log levels for informational messages
+Changes since v2:
+ * fix the blame algorithm and improve logging
+ (fix was reviewed by Jonathan Davies)
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+---
+ tools/ocaml/xenstored/history.ml | 12 ++++++++++
+ tools/ocaml/xenstored/process.ml | 50 ++++++++++++++++++++++++++++++++--------
+ 2 files changed, 52 insertions(+), 10 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/history.ml b/tools/ocaml/xenstored/history.ml
+index 6f7a282..e941e2b 100644
+--- a/tools/ocaml/xenstored/history.ml
++++ b/tools/ocaml/xenstored/history.ml
+@@ -58,3 +58,15 @@ let push (x: history_record) =
+ match dom with
+ | None -> () (* treat socket connections as always free to conflict *)
+ | Some d -> if not (Domain.is_free_to_conflict d) then history := x :: !history
++
++(* Find the connections from records since commit-count [since] for which [f record] returns [true] *)
++let filter_connections ~since ~f =
++ (* The "mem" call is an optimisation, to avoid calling f if we have picked con already. *)
++ (* Using a hash table rather than a list is to optimise the "mem" call. *)
++ List.fold_left (fun acc hist_rec ->
++ if hist_rec.finish_count > since
++ && not (Hashtbl.mem acc hist_rec.con)
++ && f hist_rec
++ then Hashtbl.replace acc hist_rec.con ();
++ acc
++ ) (Hashtbl.create 1023) !history
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 1ed1a8f..5e5a1ab 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -16,6 +16,7 @@
+
+ let error fmt = Logging.error "process" fmt
+ let info fmt = Logging.info "process" fmt
++let debug fmt = Logging.debug "process" fmt
+
+ open Printf
+ open Stdext
+@@ -25,6 +26,7 @@ exception Transaction_nested
+ exception Domain_not_match
+ exception Invalid_Cmd_Args
+
++(* This controls the do_debug fn in this module, not the debug logging-function. *)
+ let allow_debug = ref false
+
+ let c_int_of_string s =
+@@ -308,23 +310,51 @@ let transaction_replay c t doms cons =
+ false
+ | Transaction.Full(id, oldstore, cstore) ->
+ let tid = Connection.start_transaction c cstore in
+- let new_t = Transaction.make ~internal:true tid cstore in
++ let replay_t = Transaction.make ~internal:true tid cstore in
+ let con = sprintf "r(%d):%s" id (Connection.get_domstr c) in
+- let perform_exn (request, response) =
+- write_access_log ~ty:request.Packet.ty ~tid ~con ~data:request.Packet.data;
++
++ let perform_exn ~wlog txn (request, response) =
++ if wlog then write_access_log ~ty:request.Packet.ty ~tid ~con ~data:request.Packet.data;
+ let fct = function_of_type_simple_op request.Packet.ty in
+- let response' = input_handle_error ~cons ~doms ~fct ~con:c ~t:new_t ~req:request in
+- write_response_log ~ty:request.Packet.ty ~tid ~con ~response:response';
+- if not(Packet.response_equal response response') then raise Transaction_again in
++ let response' = input_handle_error ~cons ~doms ~fct ~con:c ~t:txn ~req:request in
++ if wlog then write_response_log ~ty:request.Packet.ty ~tid ~con ~response:response';
++ if not(Packet.response_equal response response') then raise Transaction_again
++ in
+ finally
+ (fun () ->
+ try
+ Logging.start_transaction ~con ~tid;
+- List.iter perform_exn (Transaction.get_operations t);
+- Logging.end_transaction ~con ~tid;
++ List.iter (perform_exn ~wlog:true replay_t) (Transaction.get_operations t); (* May throw EAGAIN *)
+
+- Transaction.commit ~con new_t
+- with e ->
++ Logging.end_transaction ~con ~tid;
++ Transaction.commit ~con replay_t
++ with
++ | Transaction_again -> (
++ let victim_domstr = Connection.get_domstr c in
++ debug "Apportioning blame for EAGAIN in txn %d, domain=%s" id victim_domstr;
++ let punish guilty_con =
++ debug "Blaming domain %s for conflict with domain %s txn %d"
++ (Connection.get_domstr guilty_con) victim_domstr id;
++ Connection.decr_conflict_credit doms guilty_con
++ in
++ let judge_and_sentence hist_rec = (
++ let can_apply_on store = (
++ let store = Store.copy store in
++ let trial_t = Transaction.make ~internal:true Transaction.none store in
++ try List.iter (perform_exn ~wlog:false trial_t) (Transaction.get_operations t);
++ true
++ with Transaction_again -> false
++ ) in
++ if can_apply_on hist_rec.History.before
++ && not (can_apply_on hist_rec.History.after)
++ then (punish hist_rec.History.con; true)
++ else false
++ ) in
++ let guilty_cons = History.filter_connections ~since:t.Transaction.start_count ~f:judge_and_sentence in
++ if Hashtbl.length guilty_cons = 0 then debug "Found no culprit for conflict in %s: must be self or not in history." con;
++ false
++ )
++ | e ->
+ info "transaction_replay %d caught: %s" tid (Printexc.to_string e);
+ false
+ )
+--
+2.1.4
+