core: Transition device close event to use event_data_lock

This change removes the device_close_lock and uses the shared event
data lock to protect the value of the device_close counter.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

4 files changed, 20 insertions, 24 deletions

diff --git a/libusb/core.c b/libusb/core.c
index 5d1b48d..87cb776 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -1400,18 +1400,18 @@ void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
 	 * descriptor from the polling loop. */
 
 	/* record that we are closing a device */
-	usbi_mutex_lock(&ctx->device_close_lock);
+	usbi_mutex_lock(&ctx->event_data_lock);
 	ctx->device_close++;
-	usbi_mutex_unlock(&ctx->device_close_lock);
+	usbi_mutex_unlock(&ctx->event_data_lock);
 
 	/* write some data on control pipe to interrupt event handlers */
 	r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
 	if (r <= 0) {
 		usbi_warn(ctx, "internal signalling write failed, closing anyway");
 		do_close(ctx, dev_handle);
-		usbi_mutex_lock(&ctx->device_close_lock);
+		usbi_mutex_lock(&ctx->event_data_lock);
 		ctx->device_close--;
-		usbi_mutex_unlock(&ctx->device_close_lock);
+		usbi_mutex_unlock(&ctx->event_data_lock);
 		return;
 	}
 
@@ -1427,9 +1427,9 @@ void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
 	do_close(ctx, dev_handle);
 
 	/* we're done with closing this device */
-	usbi_mutex_lock(&ctx->device_close_lock);
+	usbi_mutex_lock(&ctx->event_data_lock);
 	ctx->device_close--;
-	usbi_mutex_unlock(&ctx->device_close_lock);
+	usbi_mutex_unlock(&ctx->event_data_lock);
 
 	/* Release event handling lock and wake up event waiters */
 	libusb_unlock_events(ctx);
diff --git a/libusb/io.c b/libusb/io.c
index 2b3c755..029ed57 100644
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -1112,7 +1112,6 @@ int usbi_io_init(struct libusb_context *ctx)
 
 	usbi_mutex_init(&ctx->flying_transfers_lock, NULL);
 	usbi_mutex_init(&ctx->pollfds_lock, NULL);
-	usbi_mutex_init(&ctx->device_close_lock, NULL);
 	usbi_mutex_init_recursive(&ctx->events_lock, NULL);
 	usbi_mutex_init(&ctx->event_data_lock, NULL);
 	usbi_mutex_init(&ctx->event_waiters_lock, NULL);
@@ -1174,7 +1173,6 @@ err_close_pipe:
 err:
 	usbi_mutex_destroy(&ctx->flying_transfers_lock);
 	usbi_mutex_destroy(&ctx->pollfds_lock);
-	usbi_mutex_destroy(&ctx->device_close_lock);
 	usbi_mutex_destroy(&ctx->events_lock);
 	usbi_mutex_destroy(&ctx->event_data_lock);
 	usbi_mutex_destroy(&ctx->event_waiters_lock);
@@ -1198,7 +1196,6 @@ void usbi_io_exit(struct libusb_context *ctx)
 #endif
 	usbi_mutex_destroy(&ctx->flying_transfers_lock);
 	usbi_mutex_destroy(&ctx->pollfds_lock);
-	usbi_mutex_destroy(&ctx->device_close_lock);
 	usbi_mutex_destroy(&ctx->events_lock);
 	usbi_mutex_destroy(&ctx->event_data_lock);
 	usbi_mutex_destroy(&ctx->event_waiters_lock);
@@ -1659,9 +1656,9 @@ int API_EXPORTED libusb_try_lock_events(libusb_context *ctx)
 
 	/* is someone else waiting to close a device? if so, don't let this thread
 	 * start event handling */
-	usbi_mutex_lock(&ctx->device_close_lock);
+	usbi_mutex_lock(&ctx->event_data_lock);
 	ru = ctx->device_close;
-	usbi_mutex_unlock(&ctx->device_close_lock);
+	usbi_mutex_unlock(&ctx->event_data_lock);
 	if (ru) {
 		usbi_dbg("someone else is closing a device");
 		return 1;
@@ -1750,9 +1747,9 @@ int API_EXPORTED libusb_event_handling_ok(libusb_context *ctx)
 
 	/* is someone else waiting to close a device? if so, don't let this thread
 	 * continue event handling */
-	usbi_mutex_lock(&ctx->device_close_lock);
+	usbi_mutex_lock(&ctx->event_data_lock);
 	r = ctx->device_close;
-	usbi_mutex_unlock(&ctx->device_close_lock);
+	usbi_mutex_unlock(&ctx->event_data_lock);
 	if (r) {
 		usbi_dbg("someone else is closing a device");
 		return 0;
@@ -1778,9 +1775,9 @@ int API_EXPORTED libusb_event_handler_active(libusb_context *ctx)
 
 	/* is someone else waiting to close a device? if so, don't let this thread
 	 * start event handling -- indicate that event handling is happening */
-	usbi_mutex_lock(&ctx->device_close_lock);
+	usbi_mutex_lock(&ctx->event_data_lock);
 	r = ctx->device_close;
-	usbi_mutex_unlock(&ctx->device_close_lock);
+	usbi_mutex_unlock(&ctx->event_data_lock);
 	if (r) {
 		usbi_dbg("someone else is closing a device");
 		return 1;
@@ -2062,9 +2059,9 @@ redo_poll:
 
 		/* read the dummy data from the control pipe unless someone is closing
 		 * a device */
-		usbi_mutex_lock(&ctx->device_close_lock);
+		usbi_mutex_lock(&ctx->event_data_lock);
 		ru = ctx->device_close;
-		usbi_mutex_unlock(&ctx->device_close_lock);
+		usbi_mutex_unlock(&ctx->event_data_lock);
 		if (!ru) {
 			ret = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
 			if (ret != sizeof(dummy)) {
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index b1c056e..5548b80 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -245,7 +245,7 @@ struct libusb_context {
 	int debug_fixed;
 
 	/* internal control pipe, used for interrupting event handling when
-	 * something needs to modify poll fds. */
+	 * an internal event occurs. */
 	int ctrl_pipe[2];
 
 	struct list_head usb_devs;
@@ -277,11 +277,6 @@ struct libusb_context {
 	unsigned int pollfds_modified;
 	usbi_mutex_t pollfds_lock;
 
-	/* a counter that is set when we want to interrupt event handling, in order
-	 * to safely close a device, and a lock to protect it. */
-	unsigned int device_close;
-	usbi_mutex_t device_close_lock;
-
 	/* user callbacks for pollfd changes */
 	libusb_pollfd_added_cb fd_added_cb;
 	libusb_pollfd_removed_cb fd_removed_cb;
@@ -296,6 +291,10 @@ struct libusb_context {
 	/* A lock to protect internal context event data. */
 	usbi_mutex_t event_data_lock;
 
+	/* A counter that is set when we want to interrupt and prevent event handling,
+	 * in order to safely close a device. Protected by event_data_lock. */
+	unsigned int device_close;
+
 	/* used to wait for event completion in threads other than the one that is
 	 * event handling */
 	usbi_mutex_t event_waiters_lock;
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 4313410..3ac4f9e 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 10933
+#define LIBUSB_NANO 10934