Ivo Ivanov : wineusb.sys: Move event handling to a single thread.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 46360dd73279c5bdd9a8e9e1e793bf7f34151f6d
URL:    https://gitlab.winehq.org/wine/wine/-/commit/46360dd73279c5bdd9a8e9e1e793bf7...

Author: Ivo Ivanov <logos128(a)gmail.com>
Date:   Sun Sep  4 11:47:37 2022 +0300

wineusb.sys: Move event handling to a single thread.

Also fixes a segmentation fault on exit of winedevice.exe.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=52213

---

 dlls/wineusb.sys/unixlib.c | 57 +++++++++++++++++++++++-----------------------
 dlls/wineusb.sys/unixlib.h |  5 ++--
 dlls/wineusb.sys/wineusb.c | 37 +++++++++++-------------------
 3 files changed, 43 insertions(+), 56 deletions(-)

diff --git a/dlls/wineusb.sys/unixlib.c b/dlls/wineusb.sys/unixlib.c
index f269d3e96fd..278750c37f6 100644
--- a/dlls/wineusb.sys/unixlib.c
+++ b/dlls/wineusb.sys/unixlib.c
@@ -51,10 +51,7 @@ struct unix_device
 
 static libusb_hotplug_callback_handle hotplug_cb_handle;
 
-static bool thread_shutdown;
-
-static pthread_cond_t event_cond = PTHREAD_COND_INITIALIZER;
-static pthread_mutex_t event_mutex = PTHREAD_MUTEX_INITIALIZER;
+static volatile bool thread_shutdown;
 
 static struct usb_event *usb_events;
 static size_t usb_event_count, usb_events_capacity;
@@ -92,28 +89,21 @@ static bool array_reserve(void **elements, size_t *capacity, size_t count, size_
 
 static void queue_event(const struct usb_event *event)
 {
-    pthread_mutex_lock(&event_mutex);
     if (array_reserve((void **)&usb_events, &usb_events_capacity, usb_event_count + 1, sizeof(*usb_events)))
         usb_events[usb_event_count++] = *event;
     else
         ERR("Failed to queue event.\n");
-    pthread_mutex_unlock(&event_mutex);
-    pthread_cond_signal(&event_cond);
 }
 
-static NTSTATUS usb_get_event(void *args)
+static bool get_event(struct usb_event *event)
 {
-    const struct usb_get_event_params *params = args;
+    if (!usb_event_count) return false;
 
-    pthread_mutex_lock(&event_mutex);
-    while (!usb_event_count)
-        pthread_cond_wait(&event_cond, &event_mutex);
-    *params->event = usb_events[0];
+    *event = usb_events[0];
     if (--usb_event_count)
         memmove(usb_events, usb_events + 1, usb_event_count * sizeof(*usb_events));
-    pthread_mutex_unlock(&event_mutex);
 
-    return STATUS_SUCCESS;
+    return true;
 }
 
 static void add_usb_device(libusb_device *libusb_device)
@@ -239,10 +229,30 @@ static int LIBUSB_CALL hotplug_cb(libusb_context *context, libusb_device *device
 
 static NTSTATUS usb_main_loop(void *args)
 {
-    static const struct usb_event shutdown_event = {.type = USB_EVENT_SHUTDOWN};
+    const struct usb_main_loop_params *params = args;
     int ret;
 
-    TRACE("Starting libusb event thread.\n");
+    while (!thread_shutdown)
+    {
+        if (get_event(params->event)) return STATUS_PENDING;
+
+        if ((ret = libusb_handle_events(NULL)))
+            ERR("Error handling events: %s\n", libusb_strerror(ret));
+    }
+
+    libusb_exit(NULL);
+    free(usb_events);
+    usb_events = NULL;
+    usb_event_count = usb_events_capacity = 0;
+    thread_shutdown = false;
+
+    TRACE("USB main loop exiting.\n");
+    return STATUS_SUCCESS;
+}
+
+static NTSTATUS usb_init(void *args)
+{
+    int ret;
 
     if ((ret = libusb_init(NULL)))
     {
@@ -260,17 +270,6 @@ static NTSTATUS usb_main_loop(void *args)
         return STATUS_UNSUCCESSFUL;
     }
 
-    while (!thread_shutdown)
-    {
-        if ((ret = libusb_handle_events(NULL)))
-            ERR("Error handling events: %s\n", libusb_strerror(ret));
-    }
-
-    libusb_exit(NULL);
-
-    queue_event(&shutdown_event);
-
-    TRACE("Shutting down libusb event thread.\n");
     return STATUS_SUCCESS;
 }
 
@@ -566,8 +565,8 @@ const unixlib_entry_t __wine_unix_call_funcs[] =
 {
 #define X(name) [unix_ ## name] = name
     X(usb_main_loop),
+    X(usb_init),
     X(usb_exit),
-    X(usb_get_event),
     X(usb_submit_urb),
     X(usb_cancel_transfer),
     X(usb_destroy_device),
diff --git a/dlls/wineusb.sys/unixlib.h b/dlls/wineusb.sys/unixlib.h
index 0c3319969b7..eee16c8fc2b 100644
--- a/dlls/wineusb.sys/unixlib.h
+++ b/dlls/wineusb.sys/unixlib.h
@@ -31,7 +31,6 @@ enum usb_event_type
     USB_EVENT_ADD_DEVICE,
     USB_EVENT_REMOVE_DEVICE,
     USB_EVENT_TRANSFER_COMPLETE,
-    USB_EVENT_SHUTDOWN,
 };
 
 struct usb_event
@@ -53,7 +52,7 @@ struct usb_event
     } u;
 };
 
-struct usb_get_event_params
+struct usb_main_loop_params
 {
     struct usb_event *event;
 };
@@ -77,8 +76,8 @@ struct usb_destroy_device_params
 enum unix_funcs
 {
     unix_usb_main_loop,
+    unix_usb_init,
     unix_usb_exit,
-    unix_usb_get_event,
     unix_usb_submit_urb,
     unix_usb_cancel_transfer,
     unix_usb_destroy_device,
diff --git a/dlls/wineusb.sys/wineusb.c b/dlls/wineusb.sys/wineusb.c
index e9e91326a84..7848b31105e 100644
--- a/dlls/wineusb.sys/wineusb.c
+++ b/dlls/wineusb.sys/wineusb.c
@@ -165,14 +165,7 @@ static void remove_unix_device(struct unix_device *unix_device)
     IoInvalidateDeviceRelations(bus_pdo, BusRelations);
 }
 
-static HANDLE libusb_event_thread, event_thread;
-
-static DWORD CALLBACK libusb_event_thread_proc(void *arg)
-{
-    WINE_UNIX_CALL(unix_usb_main_loop, NULL);
-
-    return 0;
-}
+static HANDLE event_thread;
 
 static void complete_irp(IRP *irp)
 {
@@ -187,18 +180,18 @@ static void complete_irp(IRP *irp)
 static DWORD CALLBACK event_thread_proc(void *arg)
 {
     struct usb_event event;
-
-    TRACE("Starting client event thread.\n");
-
-    for (;;)
+    struct usb_main_loop_params params =
     {
-        struct usb_get_event_params params =
-        {
-            .event = &event,
-        };
+        .event = &event,
+    };
 
-        WINE_UNIX_CALL(unix_usb_get_event, ¶ms);
+    TRACE("Starting event thread.\n");
 
+    if (WINE_UNIX_CALL(unix_usb_init, NULL) != STATUS_SUCCESS)
+        return 0;
+
+    while (WINE_UNIX_CALL(unix_usb_main_loop, ¶ms) == STATUS_PENDING)
+    {
         switch (event.type)
         {
             case USB_EVENT_ADD_DEVICE:
@@ -212,12 +205,11 @@ static DWORD CALLBACK event_thread_proc(void *arg)
             case USB_EVENT_TRANSFER_COMPLETE:
                 complete_irp(event.u.completed_irp);
                 break;
-
-            case USB_EVENT_SHUTDOWN:
-                TRACE("Shutting down client event thread.\n");
-                return 0;
         }
     }
+
+    TRACE("Shutting down event thread.\n");
+    return 0;
 }
 
 static NTSTATUS fdo_pnp(IRP *irp)
@@ -266,7 +258,6 @@ static NTSTATUS fdo_pnp(IRP *irp)
         }
 
         case IRP_MN_START_DEVICE:
-            libusb_event_thread = CreateThread(NULL, 0, libusb_event_thread_proc, NULL, 0, NULL);
             event_thread = CreateThread(NULL, 0, event_thread_proc, NULL, 0, NULL);
 
             irp->IoStatus.Status = STATUS_SUCCESS;
@@ -281,8 +272,6 @@ static NTSTATUS fdo_pnp(IRP *irp)
             struct usb_device *device, *cursor;
 
             WINE_UNIX_CALL(unix_usb_exit, NULL);
-            WaitForSingleObject(libusb_event_thread, INFINITE);
-            CloseHandle(libusb_event_thread);
             WaitForSingleObject(event_thread, INFINITE);
             CloseHandle(event_thread);