From bc4362edacedb40c6edb9e855aa234c066b8292f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Tue, 27 Sep 2011 08:51:51 +0200 Subject: beam_lib: Handle rare race in the crypto key server functionality In rare circumstances, there can be a race when the crypto key server is started by beam_lib:crypto_key_fun/1 shortly after stopping it using beam_lib:clear_crypto_key_fun/0. The race occurs because the crypto key server first sends back the reply to the calling process, then terminates. (The race is probably more likely to happen on CPUs with hyper threading.) --- lib/stdlib/src/beam_lib.erl | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'lib/stdlib/src/beam_lib.erl') diff --git a/lib/stdlib/src/beam_lib.erl b/lib/stdlib/src/beam_lib.erl index d9c645d787..fdfbb2e998 100644 --- a/lib/stdlib/src/beam_lib.erl +++ b/lib/stdlib/src/beam_lib.erl @@ -893,13 +893,17 @@ call_crypto_server(Req) -> gen_server:call(?CRYPTO_KEY_SERVER, Req, infinity) catch exit:{noproc,_} -> - start_crypto_server(), - erlang:yield(), - call_crypto_server(Req) + %% Not started. + call_crypto_server_1(Req); + exit:{normal,_} -> + %% The process finished just as we called it. + call_crypto_server_1(Req) end. -start_crypto_server() -> - gen_server:start({local,?CRYPTO_KEY_SERVER}, ?MODULE, [], []). +call_crypto_server_1(Req) -> + gen_server:start({local,?CRYPTO_KEY_SERVER}, ?MODULE, [], []), + erlang:yield(), + call_crypto_server(Req). -spec init([]) -> {'ok', #state{}}. -- cgit v1.2.3