From a9e579341181ed877379de022a261da81fc7cf8c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?John=20H=C3=B6gberg?= Date: Wed, 27 Jun 2018 14:40:18 +0200 Subject: Fix a race condition when generating async operation ids The counter used for generating async operation ids was a plain int shared between all ports, which was incorrect but mostly worked fine since the ids only had to be unique on a per-port basis. However, some compilers (notably GCC 8.1.1) generated code that assumed that this value didn't change between reads. Using a shortened version of enq_async_w_tmo as an example: int id = async_ref++; op->id = id; //A return id; //B In GCC 7 and earlier, `async_ref` would be read once and assigned to `id` before being incremented, which kept the values at A and B consistent. In GCC 8, `async_ref` was read when assigned at A and read again at B, and then incremented, which made them inconsistent if we raced with another port. This commit fixes the issue by removing `async_ref` altogether and replacing it with a per-port counter which makes it impossible to race with someone else. --- erts/emulator/drivers/common/inet_drv.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'erts') diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c index ebd13e6f05..3029958f26 100644 --- a/erts/emulator/drivers/common/inet_drv.c +++ b/erts/emulator/drivers/common/inet_drv.c @@ -1025,6 +1025,7 @@ typedef struct { inet_async_op* oph; /* queue head or NULL */ inet_async_op* opt; /* queue tail or NULL */ inet_async_op op_queue[INET_MAX_ASYNC]; /* call queue */ + int op_ref; /* queue reference generator */ int active; /* 0 = passive, 1 = active, 2 = active once */ Sint16 active_count; /* counter for {active,N} */ @@ -1273,8 +1274,7 @@ static int packet_inet_output(udp_descriptor* udesc, HANDLE event); /* convert descriptor pointer to inet_descriptor pointer */ #define INETP(d) (&(d)->inet) -static int async_ref = 0; /* async reference id generator */ -#define NEW_ASYNC_ID() ((async_ref++) & 0xffff) +#define NEW_ASYNC_ID(desc) ((desc)->op_ref++ & 0xffff) /* check for transition from active to passive */ #define INET_CHECK_ACTIVE_TO_PASSIVE(inet) \ @@ -1925,7 +1925,7 @@ static void enq_multi_op(tcp_descriptor *desc, char *buf, int req, ErlDrvTermData caller, MultiTimerData *timeout, ErlDrvMonitor *monitorp) { - int id = NEW_ASYNC_ID(); + int id = NEW_ASYNC_ID(INETP(desc)); enq_old_multi_op(desc,id,req,caller,timeout,monitorp); if (buf != NULL) put_int16(id, buf); @@ -1994,7 +1994,7 @@ static int remove_multi_op(tcp_descriptor *desc, int *id_p, int *req_p, static int enq_async_w_tmo(inet_descriptor* desc, char* buf, int req, unsigned timeout, ErlDrvMonitor *monitorp) { - int id = NEW_ASYNC_ID(); + int id = NEW_ASYNC_ID(desc); inet_async_op* opp; if ((opp = desc->oph) == NULL) /* queue empty */ @@ -8310,6 +8310,7 @@ static ErlDrvData inet_start(ErlDrvPort port, int size, int protocol) desc->delimiter = '\n'; /* line delimiting char */ desc->oph = NULL; desc->opt = NULL; + desc->op_ref = 0; desc->peer_ptr = NULL; desc->name_ptr = NULL; -- cgit v1.2.3 From 3a480fa8d1f50bf269a8f0227b9c640aa2058d10 Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Fri, 29 Jun 2018 14:30:28 +0200 Subject: Update version numbers --- erts/vsn.mk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'erts') diff --git a/erts/vsn.mk b/erts/vsn.mk index e60405215a..1df1b9142b 100644 --- a/erts/vsn.mk +++ b/erts/vsn.mk @@ -18,7 +18,7 @@ # %CopyrightEnd% # -VSN = 10.0.1 +VSN = 10.0.2 # Port number 4365 in 4.2 # Port number 4366 in 4.3 -- cgit v1.2.3 From 5c8e7e905a678e1214cab55fed38d6d93fab04cb Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Fri, 29 Jun 2018 14:30:53 +0200 Subject: Update release notes --- erts/doc/src/notes.xml | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'erts') diff --git a/erts/doc/src/notes.xml b/erts/doc/src/notes.xml index 67e27afc81..856020dfc9 100644 --- a/erts/doc/src/notes.xml +++ b/erts/doc/src/notes.xml @@ -31,6 +31,34 @@

This document describes the changes made to the ERTS application.

+
Erts 10.0.2 + +
Fixed Bugs and Malfunctions + + +

Fixed a rare bug that could cause processes to be + scheduled after they had been freed.

+

+ Own Id: OTP-15067 Aux Id: ERL-573

+ + +
+ + +
Known Bugs and Problems + + +

Fixed a race condition in the inet driver that could + cause receive to hang when the emulator was compiled with + gcc 8.

+

+ Own Id: OTP-15158 Aux Id: ERL-654

+ + +
+ +
+
Erts 10.0.1
Fixed Bugs and Malfunctions -- cgit v1.2.3