When the timer thread is created in wince_init(), it performs an initialisation
phase in which it uses QueryPerformanceFrequency() to determine if there is a
high resolution timer available, and sets hires_frequency and hires_ticks_to_ps
appropriately. However, since wince_init() does not wait for this initialisation
phase to complete, wince_clock_gettime() can be called before hires_frequency
and hires_ticks_to_ps have been updated. This can result in
wince_clock_gettime() temporarily returning real-time clock values even though
the platform supports a monotonic clock.
This patch addresses this issue by having wince_init() wait until the timer
thread has initialised before returning.
Signed-off-by: Simon Haggett <simon.hagg...@realvnc.com>
---
libusb/os/wince_usb.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/libusb/os/wince_usb.c b/libusb/os/wince_usb.c
index e4a6633..90c129b 100644
--- a/libusb/os/wince_usb.c
+++ b/libusb/os/wince_usb.c
@@ -234,6 +234,12 @@ static int wince_init(struct libusb_context *ctx)
usbi_err(ctx, "Unable to create timer thread -
aborting");
goto init_exit;
}
+
+ // Wait for timer thread to init before continuing.
+ if (WaitForSingleObject(timer_response, INFINITE) !=
WAIT_OBJECT_0) {
+ usbi_err(ctx, "Failed to wait for timer thread to
become ready - aborting");
+ goto init_exit;
+ }
}
// At this stage, either we went through full init successfully, or
didn't need to
r = LIBUSB_SUCCESS;
@@ -877,6 +883,11 @@ unsigned __stdcall wince_clock_gettime_threaded(void*
param)
usbi_dbg("hires timer available (Frequency: %"PRIu64" Hz)",
hires_frequency);
}
+ // Signal wince_init() that we're ready to service requests
+ if (ReleaseSemaphore(timer_response, 1, NULL) == 0) {
+ usbi_dbg("unable to release timer semaphore: %s",
windows_error_str(0));
+ }
+
// Main loop - wait for requests
while (1) {
timer_index = WaitForMultipleObjects(2, timer_request, FALSE,
INFINITE) - WAIT_OBJECT_0;
@@ -911,7 +922,7 @@ unsigned __stdcall wince_clock_gettime_threaded(void* param)
nb_responses =
InterlockedExchange((LONG*)&request_count[0], 0);
if ( (nb_responses)
&& (ReleaseSemaphore(timer_response, nb_responses,
NULL) == 0) ) {
- usbi_dbg("unable to release timer semaphore %d:
%s", windows_error_str(0));
+ usbi_dbg("unable to release timer semaphore:
%s", windows_error_str(0));
}
continue;
case 1: // time to quit
--
1.7.9.5
------------------------------------------------------------------------------
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