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.

7 files changed, 37 insertions, 2 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);