summaryrefslogtreecommitdiff
path: root/rts/posix
diff options
context:
space:
mode:
authorBen Gamari <ben@smart-cactus.org>2019-12-01 11:55:46 -0500
committerBen Gamari <ben@smart-cactus.org>2020-10-24 21:02:11 -0400
commitf97c59ce014687979fa731db7227773fa83d2156 (patch)
treec6ef7fd5d08d6a48ed23b256cab1a9fef890c901 /rts/posix
parentbf1b0bc78da7dbe5f6fbda54b37a9cb165ff857f (diff)
downloadhaskell-f97c59ce014687979fa731db7227773fa83d2156.tar.gz
Mitigate data races in event manager startup/shutdownwip/tsan/event-mgr
Diffstat (limited to 'rts/posix')
-rw-r--r--rts/posix/Signals.c48
1 files changed, 28 insertions, 20 deletions
diff --git a/rts/posix/Signals.c b/rts/posix/Signals.c
index 2e534042f3..5ad688bc2f 100644
--- a/rts/posix/Signals.c
+++ b/rts/posix/Signals.c
@@ -128,7 +128,7 @@ more_handlers(int sig)
}
// Here's the pipe into which we will send our signals
-static volatile int io_manager_wakeup_fd = -1;
+static int io_manager_wakeup_fd = -1;
static int timer_manager_control_wr_fd = -1;
#define IO_MANAGER_WAKEUP 0xff
@@ -136,7 +136,7 @@ static int timer_manager_control_wr_fd = -1;
#define IO_MANAGER_SYNC 0xfd
void setTimerManagerControlFd(int fd) {
- timer_manager_control_wr_fd = fd;
+ RELAXED_STORE(&timer_manager_control_wr_fd, fd);
}
void
@@ -144,7 +144,7 @@ setIOManagerWakeupFd (int fd)
{
// only called when THREADED_RTS, but unconditionally
// compiled here because GHC.Event.Control depends on it.
- io_manager_wakeup_fd = fd;
+ SEQ_CST_STORE(&io_manager_wakeup_fd, fd);
}
/* -----------------------------------------------------------------------------
@@ -154,14 +154,15 @@ void
ioManagerWakeup (void)
{
int r;
+ const int wakeup_fd = SEQ_CST_LOAD(&io_manager_wakeup_fd);
// Wake up the IO Manager thread by sending a byte down its pipe
- if (io_manager_wakeup_fd >= 0) {
+ if (wakeup_fd >= 0) {
#if defined(HAVE_EVENTFD)
StgWord64 n = (StgWord64)IO_MANAGER_WAKEUP;
- r = write(io_manager_wakeup_fd, (char *) &n, 8);
+ r = write(wakeup_fd, (char *) &n, 8);
#else
StgWord8 byte = (StgWord8)IO_MANAGER_WAKEUP;
- r = write(io_manager_wakeup_fd, &byte, 1);
+ r = write(wakeup_fd, &byte, 1);
#endif
/* N.B. If the TimerManager is shutting down as we run this
* then there is a possibility that our first read of
@@ -174,7 +175,7 @@ ioManagerWakeup (void)
* Since this is not an error condition, we do not print the error
* message in this case.
*/
- if (r == -1 && io_manager_wakeup_fd >= 0) {
+ if (r == -1 && SEQ_CST_LOAD(&io_manager_wakeup_fd) >= 0) {
sysErrorBelch("ioManagerWakeup: write");
}
}
@@ -186,21 +187,27 @@ ioManagerDie (void)
{
StgWord8 byte = (StgWord8)IO_MANAGER_DIE;
uint32_t i;
- int fd;
int r;
- if (0 <= timer_manager_control_wr_fd) {
- r = write(timer_manager_control_wr_fd, &byte, 1);
- if (r == -1) { sysErrorBelch("ioManagerDie: write"); }
- timer_manager_control_wr_fd = -1;
- }
-
- for (i=0; i < n_capabilities; i++) {
- fd = capabilities[i]->io_manager_control_wr_fd;
+ {
+ // Shut down timer manager
+ const int fd = RELAXED_LOAD(&timer_manager_control_wr_fd);
if (0 <= fd) {
r = write(fd, &byte, 1);
if (r == -1) { sysErrorBelch("ioManagerDie: write"); }
- capabilities[i]->io_manager_control_wr_fd = -1;
+ RELAXED_STORE(&timer_manager_control_wr_fd, -1);
+ }
+ }
+
+ {
+ // Shut down IO managers
+ for (i=0; i < n_capabilities; i++) {
+ const int fd = RELAXED_LOAD(&capabilities[i]->io_manager_control_wr_fd);
+ if (0 <= fd) {
+ r = write(fd, &byte, 1);
+ if (r == -1) { sysErrorBelch("ioManagerDie: write"); }
+ RELAXED_STORE(&capabilities[i]->io_manager_control_wr_fd, -1);
+ }
}
}
}
@@ -216,7 +223,7 @@ ioManagerStart (void)
{
// Make sure the IO manager thread is running
Capability *cap;
- if (timer_manager_control_wr_fd < 0 || io_manager_wakeup_fd < 0) {
+ if (SEQ_CST_LOAD(&timer_manager_control_wr_fd) < 0 || SEQ_CST_LOAD(&io_manager_wakeup_fd) < 0) {
cap = rts_lock();
ioManagerStartCap(&cap);
rts_unlock(cap);
@@ -258,9 +265,10 @@ generic_handler(int sig USED_IF_THREADS,
memcpy(buf+1, info, sizeof(siginfo_t));
}
- if (0 <= timer_manager_control_wr_fd)
+ int timer_control_fd = RELAXED_LOAD(&timer_manager_control_wr_fd);
+ if (0 <= timer_control_fd)
{
- r = write(timer_manager_control_wr_fd, buf, sizeof(siginfo_t)+1);
+ r = write(timer_control_fd, buf, sizeof(siginfo_t)+1);
if (r == -1 && errno == EAGAIN) {
errorBelch("lost signal due to full pipe: %d\n", sig);
}