authorgravatar for jacobly@ziglang.orgJacob Young <jacobly@ziglang.org> 2025-03-28 09:13:07-04:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-07-20 10:38:38-07:00
log048a40dac72fc26fe145ac8426745e22b188d156
treea4287a98eef421b2b53940ee656966a9a805dd37
parent1d7a69cb7de7c935525428565767ab50c1198488

EventLoop: fix incorrect alignment panic

When the previous fiber did not request to be registered as an awaiter, it may not have actually been a full blown `Fiber`, so only create the `Fiber` pointer when needed.

1 files changed, 4 insertions(+), 3 deletions(-)

lib/std/Io/EventLoop.zig+4-3
......@@ -84,7 +84,6 @@ pub fn io(el: *EventLoop) Io {
8484 };
8585}
8686
87
8887pub fn init(el: *EventLoop, gpa: Allocator) error{OutOfMemory}!void {
8988 const threads_bytes = ((std.Thread.getCpuCount() catch 1) -| 1) * @sizeOf(Thread);
9089 const idle_context_offset = std.mem.alignForward(usize, threads_bytes, @alignOf(Context));
......@@ -231,9 +230,11 @@ const SwitchMessage = extern struct {
231230 register_awaiter: ?*?*Fiber,
232231
233232 fn handle(message: *const SwitchMessage, el: *EventLoop) void {
234 const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.prev_context));
235233 current_fiber_context = message.ready_context;
236 if (message.register_awaiter) |awaiter| if (@atomicRmw(?*Fiber, awaiter, .Xchg, prev_fiber, .acq_rel) == Fiber.finished) el.schedule(prev_fiber);
234 if (message.register_awaiter) |awaiter| {
235 const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.prev_context));
236 if (@atomicRmw(?*Fiber, awaiter, .Xchg, prev_fiber, .acq_rel) == Fiber.finished) el.schedule(prev_fiber);
237 }
237238 }
238239};
239240