hurd: handle EINTR during critical sections

During critical sections, signal handling is deferred and thus RPCs return
EINTR, even if SA_RESTART is set. We thus have to restart the whole critical
section in that case.

This also adds HURD_CRITICAL_UNLOCK in the cases where one wants to
break the section in the middle.

29 files changed, 139 insertions, 4 deletions

diff --git a/hurd/dtable.c b/hurd/dtable.c
index 9437f8c..bbd3bfc 100644
--- a/hurd/dtable.c
+++ b/hurd/dtable.c
@@ -189,6 +189,7 @@ ctty_new_pgrp (void)
 {
   int i;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_dtable_lock);
 
@@ -224,8 +225,18 @@ ctty_new_pgrp (void)
 	    /* This fd has a ctty-special port.  We need a new one, to tell
 	       the io server of our different process group.  */
 	    io_t new;
-	    if (__term_open_ctty (port, _hurd_pid, _hurd_pgrp, &new))
-	      new = MACH_PORT_NULL;
+	    error_t err;
+	    if ((err = __term_open_ctty (port, _hurd_pid, _hurd_pgrp, &new)))
+	      {
+		if (err == EINTR)
+		  {
+		    /* Got a signal while inside an RPC of the critical section, retry again */
+		    __mutex_unlock (&_hurd_dtable_lock);
+		    HURD_CRITICAL_UNLOCK;
+		    goto retry;
+		  }
+		new = MACH_PORT_NULL;
+	      }
 	    _hurd_port_set (&d->ctty, new);
 	  }
 
diff --git a/hurd/geteuids.c b/hurd/geteuids.c
index 840d80a..7fb8b0e 100644
--- a/hurd/geteuids.c
+++ b/hurd/geteuids.c
@@ -26,6 +26,7 @@ geteuids (int n, uid_t *uidset)
   int nuids;
   void *crit;
 
+retry:
   crit = _hurd_critical_section_lock ();
   __mutex_lock (&_hurd_id.lock);
 
@@ -33,6 +34,9 @@ geteuids (int n, uid_t *uidset)
     {
       __mutex_unlock (&_hurd_id.lock);
       _hurd_critical_section_unlock (crit);
+      if (err == EINTR)
+	/* Got a signal while inside an RPC of the critical section, retry again */
+	goto retry;
       return __hurd_fail (err);
     }
 
diff --git a/hurd/hurd/signal.h b/hurd/hurd/signal.h
index 37b7dec..db9a02f 100644
--- a/hurd/hurd/signal.h
+++ b/hurd/hurd/signal.h
@@ -277,6 +277,10 @@ _hurd_critical_section_unlock (void *our_lock)
   { void *__hurd_critical__ = _hurd_critical_section_lock ()
 #define HURD_CRITICAL_END \
       _hurd_critical_section_unlock (__hurd_critical__); } while (0)
+
+/* This one can be used inside the C scoping level, for early exits.  */
+#define HURD_CRITICAL_UNLOCK \
+      _hurd_critical_section_unlock (__hurd_critical__);
 
 /* Initialize the signal code, and start the signal thread.
    Arguments give the "init ints" from exec_startup.  */
diff --git a/hurd/hurdexec.c b/hurd/hurdexec.c
index db8989e..7dca090 100644
--- a/hurd/hurdexec.c
+++ b/hurd/hurdexec.c
@@ -123,6 +123,7 @@ _hurd_exec_paths (task_t task, file_t file,
 
   ss = _hurd_self_sigstate ();
 
+retry:
   assert (! __spin_lock_locked (&ss->critical_section_lock));
   __spin_lock (&ss->critical_section_lock);
 
@@ -429,6 +430,9 @@ _hurd_exec_paths (task_t task, file_t file,
 
   /* Safe to let signals happen now.  */
   _hurd_critical_section_unlock (ss);
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
  outargs:
   free (args);
diff --git a/hurd/hurdfchdir.c b/hurd/hurdfchdir.c
index 62a6ed1..84dc292 100644
--- a/hurd/hurdfchdir.c
+++ b/hurd/hurdfchdir.c
@@ -32,6 +32,7 @@ _hurd_change_directory_port_from_fd (struct hurd_port *portcell, int fd)
   if (!d)
     return __hurd_fail (EBADF);
 
+retry:
   HURD_CRITICAL_BEGIN;
 
   ret = HURD_PORT_USE (&d->port,
@@ -53,6 +54,9 @@ _hurd_change_directory_port_from_fd (struct hurd_port *portcell, int fd)
 		       }));
 
   HURD_CRITICAL_END;
+  if (ret == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return ret;
 }
diff --git a/hurd/hurdsock.c b/hurd/hurdsock.c
index 79395d9..04e86b4 100644
--- a/hurd/hurdsock.c
+++ b/hurd/hurdsock.c
@@ -52,6 +52,7 @@ _hurd_socket_server (int domain, int dead)
       return MACH_PORT_NULL;
     }
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&lock);
 
@@ -101,6 +102,9 @@ _hurd_socket_server (int domain, int dead)
 
   __mutex_unlock (&lock);
   HURD_CRITICAL_END;
+  if (server == MACH_PORT_NULL && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return server;
 }
diff --git a/hurd/seteuids.c b/hurd/seteuids.c
index 19db47f..df0922f 100644
--- a/hurd/seteuids.c
+++ b/hurd/seteuids.c
@@ -31,6 +31,7 @@ seteuids (int n, const uid_t *uids)
   for (i = 0; i < n; ++i)
     new[i] = uids[i];
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -47,6 +48,9 @@ seteuids (int n, const uid_t *uids)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/faccessat.c b/sysdeps/mach/hurd/faccessat.c
index f421a53..0770271 100644
--- a/sysdeps/mach/hurd/faccessat.c
+++ b/sysdeps/mach/hurd/faccessat.c
@@ -127,6 +127,7 @@ __faccessat_common (int fd, const char *file, int type, int at_flags,
 
       rcrdir = rcwdir = MACH_PORT_NULL;
 
+     retry:
       HURD_CRITICAL_BEGIN;
 
       __mutex_lock (&_hurd_id.lock);
@@ -172,6 +173,9 @@ __faccessat_common (int fd, const char *file, int type, int at_flags,
       __mutex_unlock (&_hurd_id.lock);
 
       HURD_CRITICAL_END;
+      if (err == EINTR)
+	/* Got a signal while inside an RPC of the critical section, retry again */
+	goto retry;
 
       if (rcrdir != MACH_PORT_NULL)
 	__mach_port_deallocate (__mach_task_self (), rcrdir);
diff --git a/sysdeps/mach/hurd/fork.c b/sysdeps/mach/hurd/fork.c
index 1c5299e..92a5169 100644
--- a/sysdeps/mach/hurd/fork.c
+++ b/sysdeps/mach/hurd/fork.c
@@ -70,6 +70,7 @@ __fork (void)
   __run_fork_handlers (atfork_run_prepare, true);
 
   ss = _hurd_self_sigstate ();
+retry:
   __spin_lock (&ss->critical_section_lock);
 
 #undef	LOSE
@@ -718,6 +719,9 @@ __fork (void)
   }
 
   _hurd_critical_section_unlock (ss);
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (!err)
     {
diff --git a/sysdeps/mach/hurd/getegid.c b/sysdeps/mach/hurd/getegid.c
index 5a3db22..1929d74 100644
--- a/sysdeps/mach/hurd/getegid.c
+++ b/sysdeps/mach/hurd/getegid.c
@@ -27,6 +27,7 @@ __getegid (void)
   error_t err;
   gid_t egid;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -49,6 +50,9 @@ __getegid (void)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (egid == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return egid;
 }
diff --git a/sysdeps/mach/hurd/geteuid.c b/sysdeps/mach/hurd/geteuid.c
index a7af5a9..5312d6b 100644
--- a/sysdeps/mach/hurd/geteuid.c
+++ b/sysdeps/mach/hurd/geteuid.c
@@ -27,6 +27,7 @@ __geteuid (void)
   error_t err;
   uid_t euid;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -49,6 +50,9 @@ __geteuid (void)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (euid == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return euid;
 }
diff --git a/sysdeps/mach/hurd/getgid.c b/sysdeps/mach/hurd/getgid.c
index aa13884..c89e742 100644
--- a/sysdeps/mach/hurd/getgid.c
+++ b/sysdeps/mach/hurd/getgid.c
@@ -27,6 +27,7 @@ __getgid (void)
   error_t err;
   gid_t gid;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -46,6 +47,9 @@ __getgid (void)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (gid == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return gid;
 }
diff --git a/sysdeps/mach/hurd/getgroups.c b/sysdeps/mach/hurd/getgroups.c
index 5f036f8..6b59d4a 100644
--- a/sysdeps/mach/hurd/getgroups.c
+++ b/sysdeps/mach/hurd/getgroups.c
@@ -31,6 +31,7 @@ __getgroups (int n, gid_t *gidset)
   if (n < 0)
     return __hurd_fail (EINVAL);
 
+retry:
   crit = _hurd_critical_section_lock ();
   __mutex_lock (&_hurd_id.lock);
 
@@ -38,6 +39,9 @@ __getgroups (int n, gid_t *gidset)
     {
       __mutex_unlock (&_hurd_id.lock);
       _hurd_critical_section_unlock (crit);
+      if (err == EINTR)
+	/* Got a signal while inside an RPC of the critical section, retry again */
+	goto retry;
       return __hurd_fail (err);
     }
 
diff --git a/sysdeps/mach/hurd/getresgid.c b/sysdeps/mach/hurd/getresgid.c
index 9cae591..52838b8 100644
--- a/sysdeps/mach/hurd/getresgid.c
+++ b/sysdeps/mach/hurd/getresgid.c
@@ -28,6 +28,7 @@ __getresgid (gid_t *rgid, gid_t *egid, gid_t *sgid)
 {
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -49,6 +50,9 @@ __getresgid (gid_t *rgid, gid_t *egid, gid_t *sgid)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return __hurd_fail (err);
 }
diff --git a/sysdeps/mach/hurd/getresuid.c b/sysdeps/mach/hurd/getresuid.c
index 02995db..732e416 100644
--- a/sysdeps/mach/hurd/getresuid.c
+++ b/sysdeps/mach/hurd/getresuid.c
@@ -28,6 +28,7 @@ __getresuid (uid_t *ruid, uid_t *euid, uid_t *suid)
 {
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -49,6 +50,9 @@ __getresuid (uid_t *ruid, uid_t *euid, uid_t *suid)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return __hurd_fail (err);
 }
diff --git a/sysdeps/mach/hurd/getuid.c b/sysdeps/mach/hurd/getuid.c
index fc4a441..1aadb74 100644
--- a/sysdeps/mach/hurd/getuid.c
+++ b/sysdeps/mach/hurd/getuid.c
@@ -27,6 +27,7 @@ __getuid (void)
   error_t err;
   uid_t uid;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -46,6 +47,9 @@ __getuid (void)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (uid == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return uid;
 }
diff --git a/sysdeps/mach/hurd/group_member.c b/sysdeps/mach/hurd/group_member.c
index c5256f1..72681a8 100644
--- a/sysdeps/mach/hurd/group_member.c
+++ b/sysdeps/mach/hurd/group_member.c
@@ -28,6 +28,7 @@ __group_member (gid_t gid)
   error_t err;
   void *crit;
 
+retry:
   crit = _hurd_critical_section_lock ();
   __mutex_lock (&_hurd_id.lock);
 
@@ -45,6 +46,9 @@ __group_member (gid_t gid)
 
   __mutex_unlock (&_hurd_id.lock);
   _hurd_critical_section_unlock (crit);
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setegid.c b/sysdeps/mach/hurd/setegid.c
index f0258d3..1396e19 100644
--- a/sysdeps/mach/hurd/setegid.c
+++ b/sysdeps/mach/hurd/setegid.c
@@ -29,6 +29,7 @@ setegid (gid_t gid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -55,6 +56,9 @@ setegid (gid_t gid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/seteuid.c b/sysdeps/mach/hurd/seteuid.c
index 637015c..97eb22c 100644
--- a/sysdeps/mach/hurd/seteuid.c
+++ b/sysdeps/mach/hurd/seteuid.c
@@ -29,6 +29,7 @@ seteuid (uid_t uid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -55,6 +56,9 @@ seteuid (uid_t uid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setgid.c b/sysdeps/mach/hurd/setgid.c
index 6e0672d..c6a64c9 100644
--- a/sysdeps/mach/hurd/setgid.c
+++ b/sysdeps/mach/hurd/setgid.c
@@ -32,6 +32,7 @@ __setgid (gid_t gid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -81,6 +82,9 @@ __setgid (gid_t gid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setgroups.c b/sysdeps/mach/hurd/setgroups.c
index fc78de3..cb6b899 100644
--- a/sysdeps/mach/hurd/setgroups.c
+++ b/sysdeps/mach/hurd/setgroups.c
@@ -34,6 +34,7 @@ setgroups (size_t n, const gid_t *groups)
   for (i = 0; i < n; ++i)
     new[i] = groups[i];
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -50,6 +51,9 @@ setgroups (size_t n, const gid_t *groups)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setitimer.c b/sysdeps/mach/hurd/setitimer.c
index e23e79a..4931644 100644
--- a/sysdeps/mach/hurd/setitimer.c
+++ b/sysdeps/mach/hurd/setitimer.c
@@ -339,6 +339,7 @@ __setitimer (enum __itimer_which which, const struct itimerval *new,
 	     struct itimerval *old)
 {
   void *crit;
+  int ret;
 
   switch (which)
     {
@@ -353,9 +354,15 @@ __setitimer (enum __itimer_which which, const struct itimerval *new,
       break;
     }
 
+retry:
   crit = _hurd_critical_section_lock ();
   __spin_lock (&_hurd_itimer_lock);
-  return setitimer_locked (new, old, crit, 0);
+  ret = setitimer_locked (new, old, crit, 0);
+  if (ret == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
+
+  return ret;
 }
 
 static void
diff --git a/sysdeps/mach/hurd/setregid.c b/sysdeps/mach/hurd/setregid.c
index 2fce6cf..aad736e 100644
--- a/sysdeps/mach/hurd/setregid.c
+++ b/sysdeps/mach/hurd/setregid.c
@@ -28,6 +28,7 @@ __setregid (gid_t rgid, gid_t egid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -82,6 +83,9 @@ __setregid (gid_t rgid, gid_t egid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setresgid.c b/sysdeps/mach/hurd/setresgid.c
index 8ccfd93..64b6840 100644
--- a/sysdeps/mach/hurd/setresgid.c
+++ b/sysdeps/mach/hurd/setresgid.c
@@ -29,6 +29,7 @@ __setresgid (gid_t rgid, gid_t egid, gid_t sgid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -110,6 +111,9 @@ __setresgid (gid_t rgid, gid_t egid, gid_t sgid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setresuid.c b/sysdeps/mach/hurd/setresuid.c
index d16db17..53d07cc 100644
--- a/sysdeps/mach/hurd/setresuid.c
+++ b/sysdeps/mach/hurd/setresuid.c
@@ -29,6 +29,7 @@ __setresuid (uid_t ruid, uid_t euid, uid_t suid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -111,6 +112,9 @@ __setresuid (uid_t ruid, uid_t euid, uid_t suid)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setreuid.c b/sysdeps/mach/hurd/setreuid.c
index 97328e1..d093ed9 100644
--- a/sysdeps/mach/hurd/setreuid.c
+++ b/sysdeps/mach/hurd/setreuid.c
@@ -28,6 +28,7 @@ __setreuid (uid_t ruid, uid_t euid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -82,6 +83,9 @@ __setreuid (uid_t ruid, uid_t euid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/setsid.c b/sysdeps/mach/hurd/setsid.c
index 3861f8f..698fc9c 100644
--- a/sysdeps/mach/hurd/setsid.c
+++ b/sysdeps/mach/hurd/setsid.c
@@ -32,6 +32,7 @@ __setsid (void)
   error_t err;
   unsigned int stamp;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_dtable_lock);
 
@@ -60,6 +61,9 @@ __setsid (void)
     }
 
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return err ? __hurd_fail (err) : _hurd_pgrp;
 }
diff --git a/sysdeps/mach/hurd/setuid.c b/sysdeps/mach/hurd/setuid.c
index ede3f01..4818357 100644
--- a/sysdeps/mach/hurd/setuid.c
+++ b/sysdeps/mach/hurd/setuid.c
@@ -32,6 +32,7 @@ __setuid (uid_t uid)
   auth_t newauth;
   error_t err;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
   err = _hurd_check_ids ();
@@ -86,6 +87,9 @@ __setuid (uid_t uid)
     }
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (err == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   if (err)
     return __hurd_fail (err);
diff --git a/sysdeps/mach/hurd/spawni.c b/sysdeps/mach/hurd/spawni.c
index 9bc1571..b5c9236 100644
--- a/sysdeps/mach/hurd/spawni.c
+++ b/sysdeps/mach/hurd/spawni.c
@@ -333,6 +333,7 @@ __spawni (pid_t *pid, const char *file,
 
   ss = _hurd_self_sigstate ();
 
+retry:
   assert (! __spin_lock_locked (&ss->critical_section_lock));
   __spin_lock (&ss->critical_section_lock);
 
@@ -437,7 +438,19 @@ __spawni (pid_t *pid, const char *file,
 						 MACH_PORT_RIGHT_SEND, +1));
 
   if (err)
-    goto out;
+    {
+      _hurd_critical_section_unlock (ss);
+
+      if (err == EINTR)
+	{
+	  /* Got a signal while inside an RPC of the critical section, retry again */
+	  __mach_port_deallocate (__mach_task_self (), auth);
+	  auth = MACH_PORT_NULL;
+	  goto retry;
+	}
+
+      goto out;
+    }
 
   /* Pack up the descriptor table to give the new program.
      These descriptors will need to be reauthenticated below