File 0120-Ensure-rootset-array-is-large-enough-for-a... of Package erlang

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File 0120-Ensure-rootset-array-is-large-enough-for-alias-signa.patch of Package erlang (Revision 218b3430555ecf8dc51659dea4ccdb8e)

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From 3c668113ca61c17b7d297cfa0900d04857652d18 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Fri, 21 May 2021 11:36:40 +0200
Subject: [PATCH] Ensure rootset array is large enough for alias-signals

---
 erts/emulator/beam/erl_gc.c     | 74 ++++++++++++++++++++++-----------
 erts/emulator/test/gc_SUITE.erl | 44 +++++++++++++++++++-
 2 files changed, 91 insertions(+), 27 deletions(-)

diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c
index cb21f14071..d3d79959df 100644
--- a/erts/emulator/beam/erl_gc.c
+++ b/erts/emulator/beam/erl_gc.c
@@ -2549,7 +2549,8 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
 
     if ((p->sig_qs.flags & (FS_OFF_HEAP_MSGQ
 			    | FS_OFF_HEAP_MSGQ_CHNG)) != FS_OFF_HEAP_MSGQ) {
-        Sint len;
+	Uint size;
+	ErtsMessage *mp;
 	/*
 	 * We do not have off heap message queue enabled, i.e. we
 	 * need to add signal queues to rootset...
@@ -2557,7 +2558,6 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
 
 #ifdef DEBUG
         if (p->sig_qs.flags & FS_ON_HEAP_MSGQ) {
-            ErtsMessage *mp;
             erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
             /*
              * Verify that we do not have any messages in the outer
@@ -2577,35 +2577,59 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
             erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
         }
 #endif
-        
-        len = erts_proc_sig_privqs_len(p);
 
-	/* Ensure large enough rootset... */
-	if (n + len > rootset->size) {
-	    Uint new_size = n + len;
+	size = n + erts_proc_sig_privqs_len(p);
+	if (p->sig_qs.cont) {
+	    /*
+	     * We do not know the exact size needed since
+	     * alias-message signals are not included in
+	     * length of private queues. We might have to
+	     * resize while inspecting the signal queue...
+	     */
+	    size += 128;
+	}
+	if (size > rootset->size) {
 	    ERTS_GC_ASSERT(roots == rootset->def);
 	    roots = erts_alloc(ERTS_ALC_T_ROOTSET,
-			       new_size*sizeof(Roots));
+			       size*sizeof(Roots));
 	    sys_memcpy(roots, rootset->def, n*sizeof(Roots));
-	    rootset->size = new_size;
+	    rootset->size = size;
 	}
 
-        ERTS_FOREACH_SIG_PRIVQS(
-            p, mp,
-            {
-                /* Add signal data that may refer to heap... */
-                if (ERTS_SIG_IS_INTERNAL_MSG(mp) && !mp->data.attached) {
-                    roots[n].v = mp->m;
-                    roots[n].sz = ERL_MESSAGE_REF_ARRAY_SZ;
-                    n++;
-                }
-                else if (ERTS_SIG_IS_HEAP_ALIAS_MSG(mp)) {
-                    /* Exclude message slot... */
-                    roots[n].v = &mp->m[1];
-                    roots[n].sz = ERL_MESSAGE_REF_ARRAY_SZ - 1;
-                    n++;
-                }
-            });
+	mp = p->sig_qs.first;
+	while (mp) {
+	    if (ERTS_SIG_IS_INTERNAL_MSG(mp) && !mp->data.attached) {
+		roots[n].v = mp->m;
+		roots[n].sz = ERL_MESSAGE_REF_ARRAY_SZ;
+		n++;
+	    }
+	    mp = mp->next;
+	}
+	mp = p->sig_qs.cont;
+	while (mp) {
+	    if (size <= n) {
+		Roots *old_roots = roots;
+		size += 128;
+		roots = erts_alloc(ERTS_ALC_T_ROOTSET,
+				   size*sizeof(Roots));
+		sys_memcpy(roots, old_roots, n*sizeof(Roots));
+		if (old_roots != rootset->def)
+		    erts_free(ERTS_ALC_T_ROOTSET, old_roots);
+		rootset->size = size;
+	    }
+	    if (ERTS_SIG_IS_INTERNAL_MSG(mp) && !mp->data.attached) {
+		roots[n].v = mp->m;
+		roots[n].sz = ERL_MESSAGE_REF_ARRAY_SZ;
+		n++;
+	    }
+	    else if (ERTS_SIG_IS_HEAP_ALIAS_MSG(mp)) {
+		/* Exclude message slot... */
+		roots[n].v = &mp->m[1];
+		roots[n].sz = ERL_MESSAGE_REF_ARRAY_SZ - 1;
+		n++;
+	    }
+	    mp = mp->next;
+	}
     }
 
     ASSERT(rootset->size >= n);
diff --git a/erts/emulator/test/gc_SUITE.erl b/erts/emulator/test/gc_SUITE.erl
index 810409175e..9b7488d21b 100644
--- a/erts/emulator/test/gc_SUITE.erl
+++ b/erts/emulator/test/gc_SUITE.erl
@@ -35,7 +35,8 @@
     minor_major_gc_option_async/1,
     minor_major_gc_option_self/1,
     gc_signal_order/1,
-    gc_dirty_exec_proc/1
+    gc_dirty_exec_proc/1,
+    alias_signals_in_gc/1
 ]).
 
 suite() ->
@@ -44,7 +45,8 @@ suite() ->
 all() -> 
     [grow_heap, grow_stack, grow_stack_heap, max_heap_size,
     minor_major_gc_option_self,
-    minor_major_gc_option_async, gc_signal_order, gc_dirty_exec_proc].
+    minor_major_gc_option_async, gc_signal_order, gc_dirty_exec_proc,
+    alias_signals_in_gc].
 
 
 %% Produce a growing list of elements,
@@ -331,3 +333,41 @@ check_no_unexpected_messages() ->
     after 0 ->
         ok
     end.
+
+alias_signals_in_gc(Config) when is_list(Config) ->
+    %% Make sure alias signals in rootset wont cause
+    %% crashes...
+    process_flag(scheduler, 1),
+    process_flag(priority, normal),
+    process_flag(message_queue_data, on_heap),
+    Alias = alias(),
+    %% We deactive the alias since it is no point converting
+    %% the alias signals into messages for this test...
+    unalias(Alias), 
+    Pid = spawn_opt(fun () ->
+			    alias_sig_spammer(Alias, 100000)
+		    end, [{scheduler, 1}, {priority, high}, link]),
+    erlang:yield(),
+    do_gc(10),
+    unlink(Pid),
+    exit(Pid, bang),
+    false = is_process_alive(Pid),
+    ok.
+
+alias_sig_spammer(Alias, N) ->
+    alias_sig_spammer(Alias, N, N).
+    
+alias_sig_spammer(Alias, 0, NStart) ->
+    Alias ! [hello],
+    receive after 100 -> ok end,
+    alias_sig_spammer(Alias, NStart, NStart);
+alias_sig_spammer(Alias, N, NStart) ->
+    Alias ! [hello],
+    alias_sig_spammer(Alias, N-1, NStart).
+
+do_gc(0) ->
+    ok;
+do_gc(N) ->
+    garbage_collect(),
+    receive after 100 -> ok end,
+    do_gc(N-1).
-- 
2.26.2

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File 0120-Ensure-rootset-array-is-large-enough-for-alias-signa.patch of Package erlang (Revision 218b3430555ecf8dc51659dea4ccdb8e)

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