motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-03 15:53:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

tcg: use QTree instead of GTree

Browse source 
qemu-user can hang in a multi-threaded fork. One common
reason is that when creating a TB, between fork and exec
we manipulate a GTree whose memory allocator (GSlice) is
not fork-safe.

Although POSIX does not mandate it, the system's allocator
(e.g. tcmalloc, libc malloc) is probably fork-safe.

Fix some of these hangs by using QTree, which uses the system's
allocator regardless of the Glib version that we used at
configuration time.

Tested with the test program in the original bug report, i.e.:
```

void garble() {
  int pid = fork();
  if (pid == 0) {
    exit(0);
  } else {
    int wstatus;
    waitpid(pid, &wstatus, 0);
  }
}

void supragarble(unsigned depth) {
  if (depth == 0)
    return ;

  std::thread a(supragarble, depth-1);
  std::thread b(supragarble, depth-1);
  garble();
  a.join();
  b.join();
}

int main() {
  supragarble(10);
}
```

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/285
Reported-by: Valentin David <me@valentindavid.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Emilio Cota <cota@braap.org>
Message-Id: <20230205163758.416992-3-cota@braap.org>
[rth: Add QEMU_DISABLE_CFI for all callback using functions.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Emilio Cota 2023-02-05 11:37:58 -05:00 • committed by Richard Henderson
parent e3feb2cc22
commit 1ff4a81bd3
3 changed files with 23 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

8
util/qtree.c
View file

@ -310,7 +310,7 @@ q_tree_node_next(QTreeNode *node)
*
* Since: 2.70 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static void
static void QEMU_DISABLE_CFI
q_tree_remove_all(QTree *tree)
{
QTreeNode *node;
@ -532,7 +532,7 @@ q_tree_replace(QTree *tree,
}
/* internal insert routine */
static QTreeNode *
static QTreeNode * QEMU_DISABLE_CFI
q_tree_insert_internal(QTree *tree,
gpointer key,
gpointer value,
@ -721,7 +721,7 @@ q_tree_steal(QTree *tree,
}
/* internal remove routine */
static gboolean
static gboolean QEMU_DISABLE_CFI
q_tree_remove_internal(QTree *tree,
gconstpointer key,
gboolean steal)
@ -1182,7 +1182,7 @@ q_tree_node_balance(QTreeNode *node)
return node;
}
static QTreeNode *
static QTreeNode * QEMU_DISABLE_CFI
q_tree_find_node(QTree *tree,
gconstpointer key)
{