Block signals in the ticker thread

This avoids surprises in the non-threaded runtime with blocked signals killing
the process because they're only blocked in the main thread and not in the
ticker thread.

Also backport improved compile-time detection of pthread_setname_np() and/or

3 files changed, 102 insertions, 13 deletions

diff --git a/configure.ac b/configure.ac
index c680bf04b5..44586446dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1162,20 +1162,72 @@ AC_CHECK_FUNC(pthread_create,
 AC_DEFINE_UNQUOTED([NEED_PTHREAD_LIB], [$need_lpthread],
     [Define 1 if we need to link code using pthreads with -lpthread])
 
+dnl Setting thread names
+dnl ~~~~~~~~~~~~~~~~~~~~
+dnl The portability situation here is complicated:
+dnl
+dnl * FreeBSD supports pthread_set_name_np in <pthread_np.h>
+dnl   and (if not _POSIX_SOURCE) pthread_setname_np() in <pthread.h>
+dnl   because of the conditional visibility, we prefer the former.
+dnl * glibc supports pthread_setname_np
+dnl * Darwin supports pthread_setname_np but does not take a
+dnl   pthread_t argument.
+dnl
+AC_CHECK_HEADERS([pthread_np.h])
+
 dnl ** pthread_setname_np is a recent addition to glibc, and OS X has
 dnl    a different single-argument version.
 AC_CHECK_LIB(pthread, pthread_setname_np)
-AC_MSG_CHECKING(for pthread_setname_np)
-AC_LINK_IFELSE([AC_LANG_PROGRAM(
-[[
-#define _GNU_SOURCE
-#include <pthread.h>
-]],
-[[pthread_setname_np(pthread_self(), "name");]])],
+
+AC_MSG_CHECKING([for pthread_setname_np (Darwin)])
+AC_LINK_IFELSE([
+  AC_LANG_PROGRAM(
+    [[
+    #include <pthread.h>
+    ]],
+    [[pthread_setname_np("name");]]
+  )],
+  [
+    AC_MSG_RESULT(yes)
+    AC_DEFINE([HAVE_PTHREAD_SETNAME_NP_DARWIN], [1],
+      [Define to 1 if you have the Darwin version of pthread_setname_np])
+  ],
+  AC_MSG_RESULT(no)
+)
+
+dnl glibc
+AC_MSG_CHECKING([for pthread_setname_np (glibc)])
+AC_LINK_IFELSE([
+  AC_LANG_PROGRAM(
+    [[
+    #define _GNU_SOURCE
+    #include <pthread.h>
+    ]],
+    [[pthread_setname_np(pthread_self(), "name");]]
+  )],
+  [
     AC_MSG_RESULT(yes)
     AC_DEFINE([HAVE_PTHREAD_SETNAME_NP], [1],
-      [Define to 1 if you have the glibc version of pthread_setname_np]),
-    AC_MSG_RESULT(no)
+      [Define to 1 if you have the glibc version of pthread_setname_np])
+  ],
+  AC_MSG_RESULT(no)
+)
+
+dnl FreeBSD
+AC_MSG_CHECKING([for pthread_set_name_np])
+AC_LINK_IFELSE([
+  AC_LANG_PROGRAM(
+    [[
+    #include <pthread_np.h>
+    ]],
+    [[pthread_set_name_np(pthread_self(), "name");]]
+  )],
+  [
+    AC_MSG_RESULT(yes)
+    AC_DEFINE([HAVE_PTHREAD_SET_NAME_NP], [1],
+      [Define to 1 if you have pthread_set_name_np])
+  ],
+  AC_MSG_RESULT(no)
 )
 
 dnl ** check for eventfd which is needed by the I/O manager
diff --git a/rts/posix/OSThreads.c b/rts/posix/OSThreads.c
index 6c09f86c7f..481b0f8c17 100644
--- a/rts/posix/OSThreads.c
+++ b/rts/posix/OSThreads.c
@@ -30,7 +30,7 @@
 
 #if defined(HAVE_PTHREAD_H)
 #include <pthread.h>
-#if defined(freebsd_HOST_OS)
+#if defined(HAVE_PTHREAD_NP_H)
 #include <pthread_np.h>
 #endif
 #endif
@@ -137,8 +137,12 @@ createOSThread (OSThreadId* pId, char *name STG_UNUSED,
   int result = pthread_create(pId, NULL, startProc, param);
   if (!result) {
     pthread_detach(*pId);
-#if defined(HAVE_PTHREAD_SETNAME_NP)
+#if defined(HAVE_PTHREAD_SET_NAME_NP)
+    pthread_set_name_np(*pId, name);
+#elif defined(HAVE_PTHREAD_SETNAME_NP)
     pthread_setname_np(*pId, name);
+#elif defined(HAVE_PTHREAD_SETNAME_NP_DARWIN)
+    pthread_setname_np(name);
 #endif
   }
   return result;
diff --git a/rts/posix/itimer/Pthread.c b/rts/posix/itimer/Pthread.c
index 6f86337ff5..73b1eba5de 100644
--- a/rts/posix/itimer/Pthread.c
+++ b/rts/posix/itimer/Pthread.c
@@ -62,6 +62,9 @@
 #include <string.h>
 
 #include <pthread.h>
+#if defined(HAVE_PTHREAD_NP_H)
+#include <pthread_np.h>
+#endif
 #include <unistd.h>
 #include <fcntl.h>
 
@@ -167,6 +170,11 @@ initTicker (Time interval, TickProc handle_tick)
     itimer_interval = interval;
     stopped = false;
     exited = false;
+#if defined(HAVE_SIGNAL_H)
+    sigset_t mask, omask;
+    int sigret;
+#endif
+    int ret;
 
     initCondition(&start_cond);
     initMutex(&mutex);
@@ -174,10 +182,35 @@ initTicker (Time interval, TickProc handle_tick)
     /*
      * We can't use the RTS's createOSThread here as we need to remain attached
      * to the thread we create so we can later join to it if requested
+     *
+     * On FreeBSD 12.2 pthread_set_name_np() is unconditionally declared in
+     * <pthread_np.h>, while pthread_setname_np() is conditionally declared in
+     * <pthread.h> when _POSIX_SOURCE is not defined, but we're including
+     * <PosixSource.h>, so must use pthread_set_name_np() instead.  See similar
+     * code in "rts/posix/OSThreads.c".
+     *
+     * Create the thread with all blockable signals blocked, leaving signal
+     * handling to the main and/or other threads.  This is especially useful in
+     * the non-threaded runtime, where applications might expect sigprocmask(2)
+     * to effectively block signals.
      */
-    if (! pthread_create(&thread, NULL, itimer_thread_func, (void*)handle_tick)) {
-#if defined(HAVE_PTHREAD_SETNAME_NP)
+#if defined(HAVE_SIGNAL_H)
+    sigfillset(&mask);
+    sigret = pthread_sigmask(SIG_SETMASK, &mask, &omask);
+#endif
+    ret = pthread_create(&thread, NULL, itimer_thread_func, (void*)handle_tick);
+#if defined(HAVE_SIGNAL_H)
+    if (sigret == 0)
+        pthread_sigmask(SIG_SETMASK, &omask, NULL);
+#endif
+
+    if (ret == 0) {
+#if defined(HAVE_PTHREAD_SET_NAME_NP)
+        pthread_set_name_np(thread, "ghc_ticker");
+#elif defined(HAVE_PTHREAD_SETNAME_NP)
         pthread_setname_np(thread, "ghc_ticker");
+#elif defined(HAVE_PTHREAD_SETNAME_NP_DARWIN)
+        pthread_setname_np("ghc_ticker");
 #endif
     } else {
         barf("Itimer: Failed to spawn thread: %s", strerror(errno));