| Andrew Geissler | 95ac1b8 | 2021-03-31 14:34:31 -0500 | [diff] [blame] | 1 | From 6bd0a4b29753570a2c20b61b5ad2c0068567b7b6 Mon Sep 17 00:00:00 2001 |
| 2 | From: Philip Withnall <pwithnall@endlessos.org> |
| 3 | Date: Mon, 16 Nov 2020 16:44:29 +0000 |
| 4 | Subject: [PATCH 25/29] gthread: Use g_atomic() primitives correctly in |
| 5 | destructor list |
| 6 | MIME-Version: 1.0 |
| 7 | Content-Type: text/plain; charset=UTF-8 |
| 8 | Content-Transfer-Encoding: 8bit |
| 9 | |
| 10 | In the Windows destructor list, consistently access |
| 11 | `g_private_destructors` using atomic primitives. |
| 12 | |
| 13 | `g_atomic_pointer_compare_and_exchange()` should be equivalent to |
| 14 | `InterlockedCompareExchangePointer()`, but is a bit more understandable |
| 15 | in a general GLib context, and pairs with `g_atomic_pointer_get()`. (I |
| 16 | can’t find a Windows API equivalent for that.) |
| 17 | |
| 18 | Signed-off-by: Philip Withnall <pwithnall@endlessos.org> |
| 19 | |
| 20 | Helps: #600 |
| 21 | Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1719] |
| 22 | --- |
| 23 | glib/gthread-win32.c | 13 +++++++------ |
| 24 | 1 file changed, 7 insertions(+), 6 deletions(-) |
| 25 | |
| 26 | diff --git a/glib/gthread-win32.c b/glib/gthread-win32.c |
| 27 | index 0c37dc6c1..20aca6fa1 100644 |
| 28 | --- a/glib/gthread-win32.c |
| 29 | +++ b/glib/gthread-win32.c |
| 30 | @@ -301,7 +301,7 @@ struct _GPrivateDestructor |
| 31 | GPrivateDestructor *next; |
| 32 | }; |
| 33 | |
| 34 | -static GPrivateDestructor * volatile g_private_destructors; |
| 35 | +static GPrivateDestructor *g_private_destructors; /* (atomic) prepend-only */ |
| 36 | static CRITICAL_SECTION g_private_lock; |
| 37 | |
| 38 | static DWORD |
| 39 | @@ -329,7 +329,7 @@ g_private_get_impl (GPrivate *key) |
| 40 | g_thread_abort (errno, "malloc"); |
| 41 | destructor->index = impl; |
| 42 | destructor->notify = key->notify; |
| 43 | - destructor->next = g_private_destructors; |
| 44 | + destructor->next = g_atomic_pointer_get (&g_private_destructors); |
| 45 | |
| 46 | /* We need to do an atomic store due to the unlocked |
| 47 | * access to the destructor list from the thread exit |
| 48 | @@ -337,13 +337,14 @@ g_private_get_impl (GPrivate *key) |
| 49 | * |
| 50 | * It can double as a sanity check... |
| 51 | */ |
| 52 | - if (InterlockedCompareExchangePointer (&g_private_destructors, destructor, |
| 53 | - destructor->next) != destructor->next) |
| 54 | + if (!g_atomic_pointer_compare_and_exchange (&g_private_destructors, |
| 55 | + destructor->next, |
| 56 | + destructor)) |
| 57 | g_thread_abort (0, "g_private_get_impl(1)"); |
| 58 | } |
| 59 | |
| 60 | /* Ditto, due to the unlocked access on the fast path */ |
| 61 | - if (InterlockedCompareExchangePointer (&key->p, impl, NULL) != NULL) |
| 62 | + if (!g_atomic_pointer_compare_and_exchange (&key->p, NULL, impl)) |
| 63 | g_thread_abort (0, "g_private_get_impl(2)"); |
| 64 | } |
| 65 | LeaveCriticalSection (&g_private_lock); |
| 66 | @@ -635,7 +636,7 @@ g_thread_win32_thread_detach (void) |
| 67 | */ |
| 68 | dtors_called = FALSE; |
| 69 | |
| 70 | - for (dtor = g_private_destructors; dtor; dtor = dtor->next) |
| 71 | + for (dtor = g_atomic_pointer_get (&g_private_destructors); dtor; dtor = dtor->next) |
| 72 | { |
| 73 | gpointer value; |
| 74 | |
| 75 | -- |
| 76 | 2.30.1 |
| 77 | |