Unblock stalled i/o signals on windows

Author: jart

libc/intrin/mmap.c

@@ -660,7 +660,7 @@ static void *__mmap_impl(char *addr, size_t size, int prot, int flags, int fd,
   if (!IsWindows()) {
     struct Map *deleted = 0;
     __maps_lock();
-    if (IsWindows() || fixedmode)
+    if (fixedmode)
       if (__muntrack(res.addr, size, &deleted, 0, 0))
         STRACE("memtrack compromised by hole punch oom");
     __maps_insert(map);

libc/intrin/sig.c

@@ -492,9 +492,8 @@ textwindows void __sig_generate(int sig, int sic) {
     __sig_terminate(sig);
   }
   if (atomic_load_explicit(__sig.process, memory_order_acquire) &
-      (1ull << (sig - 1))) {
+      (1ull << (sig - 1)))
     return;
-  }
   _pthread_lock();
   for (e = dll_first(_pthread_list); e; e = dll_next(_pthread_list, e)) {
     pt = POSIXTHREAD_CONTAINER(e);
@@ -503,9 +502,8 @@ textwindows void __sig_generate(int sig, int sic) {
       continue;
     // we don't want to signal a thread that isn't running
     if (atomic_load_explicit(&pt->pt_status, memory_order_acquire) >=
-        kPosixThreadTerminated) {
+        kPosixThreadTerminated)
       continue;
-    }
     // choose this thread if it isn't masking sig
     if (!(atomic_load_explicit(&pt->tib->tib_sigmask, memory_order_acquire) &
           (1ull << (sig - 1)))) {
@@ -756,11 +754,26 @@ HAIRY static uint32_t __sig_worker(void *arg) {
       __sig_generate(sig, SI_KERNEL);
     }
 
+    // unblock stalled i/o signals in threads
+    _pthread_lock();
+    for (struct Dll *e = dll_first(_pthread_list); e;
+         e = dll_next(_pthread_list, e)) {
+      struct PosixThread *pt = POSIXTHREAD_CONTAINER(e);
+      if (atomic_load_explicit(&pt->pt_status, memory_order_acquire) >=
+          kPosixThreadTerminated)
+        break;
+      if (atomic_load_explicit(&pt->pt_blocker, memory_order_acquire) &&
+          (atomic_load_explicit(&pt->tib->tib_sigpending,
+                                memory_order_acquire) &
+           ~atomic_load_explicit(&pt->pt_blkmask, memory_order_acquire)))
+        __sig_wake(pt, 0);
+    }
+    _pthread_unlock();
+
     // unblock stalled asynchronous signals in threads
-    struct PosixThread *mark;
     for (;;) {
       sigset_t pending, mask;
-      mark = 0;
+      struct PosixThread *mark = 0;
       _pthread_lock();
       for (struct Dll *e = dll_first(_pthread_list); e;
            e = dll_next(_pthread_list, e)) {
@@ -790,6 +803,7 @@ HAIRY static uint32_t __sig_worker(void *arg) {
         pending &= ~(1ull << (sig - 1));
         __sig_killer(mark, sig, SI_KERNEL);
       }
+      _pthread_unref(mark);
     }
 
     // wait until next scheduler quantum

test/posix/sa_resethand2_test.c

@@ -1,27 +1,20 @@
-/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
-│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
-╞══════════════════════════════════════════════════════════════════════════════╡
-│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
-│                                                                              │
-│ Permission to use, copy, modify, and/or distribute this software for         │
-│ any purpose with or without fee is hereby granted, provided that the         │
-│ above copyright notice and this permission notice appear in all copies.      │
-│                                                                              │
-│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
-│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
-│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
-│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
-│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
-│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
-│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
-│ PERFORMANCE OF THIS SOFTWARE.                                                │
-╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/calls/calls.h"
-#include "libc/calls/struct/sigaction.h"
-#include "libc/calls/struct/sigset.h"
-#include "libc/dce.h"
-#include "libc/sysv/consts/sa.h"
-#include "libc/sysv/consts/sig.h"
+// Copyright 2024 Justine Alexandra Roberts Tunney
+//
+// Permission to use, copy, modify, and/or distribute this software for
+// any purpose with or without fee is hereby granted, provided that the
+// above copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+// WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+// AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+// DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+// PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+// TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+#include <signal.h>
+#include <unistd.h>
 
 volatile int handler_invoked;
 
@@ -33,24 +26,17 @@ int main() {
   sigset_t mask, oldmask;
   struct sigaction sa, current_sa;
 
-  if (IsWindows()) {
-    // TODO(jart): support non-fatal signals between processes
-    return 0;
-  }
-
   sa.sa_handler = signal_handler;
   sa.sa_flags = SA_RESETHAND;
   sigemptyset(&sa.sa_mask);
 
-  if (sigaction(SIGINT, &sa, 0) == -1) {
+  if (sigaction(SIGINT, &sa, 0) == -1)
     return 1;
-  }
 
   sigemptyset(&mask);
   sigaddset(&mask, SIGINT);
-  if (sigprocmask(SIG_BLOCK, &mask, &oldmask) == -1) {
+  if (sigprocmask(SIG_BLOCK, &mask, &oldmask) == -1)
     return 2;
-  }
 
   int pid = fork();
   if (pid == -1) {
@@ -60,15 +46,12 @@ int main() {
     return 0;
   } else {
     sigsuspend(&oldmask);
-    if (!handler_invoked) {
+    if (!handler_invoked)
       return 4;
-    }
-    if (sigaction(SIGINT, 0, &current_sa) == -1) {
+    if (sigaction(SIGINT, 0, &current_sa) == -1)
       return 5;
-    }
-    if (current_sa.sa_handler != SIG_DFL) {
+    if (current_sa.sa_handler != SIG_DFL)
       return 6;
-    }
     return 0;
   }
 }

test/posix/signal_latency_test.c

@@ -133,10 +133,6 @@ int main() {
   if (IsOpenbsd())
     return 0;
 
-  // TODO(jart): Why is this test flaky on Windows?
-  if (IsWindows())
-    return 0;
-
   // Block SIGUSR1 and SIGUSR2 in main thread
   sigset_t block_set;
   sigemptyset(&block_set);