cdc device: claim endpoint before checking fifo availability

- add pre-check to reduce mutex lock in usbd_edpt_claim

1 files changed, 4 insertions, 1 deletions

diff --git a/src/device/usbd.c b/src/device/usbd.c
index 8fc0092eb..dfe30578e 100644
--- a/src/device/usbd.c
+++ b/src/device/usbd.c
@@ -1100,11 +1100,14 @@ bool usbd_edpt_claim(uint8_t rhport, uint8_t ep_addr)
   uint8_t const dir   = tu_edpt_dir(ep_addr);
 
 #if CFG_TUSB_OS != OPT_OS_NONE
+  // pre-check to help reducing mutex lock
+  TU_VERIFY((_usbd_dev.ep_status[epnum][dir].busy == 0) && (_usbd_dev.ep_status[epnum][dir].claimed == 0));
+
   osal_mutex_lock(_usbd_mutex, OSAL_TIMEOUT_WAIT_FOREVER);
 #endif
 
   // can only claim the endpoint if it is not busy and not claimed yet.
-  bool ret = (_usbd_dev.ep_status[epnum][dir].busy == 0) && (_usbd_dev.ep_status[epnum][dir].claimed == 0);
+  bool const ret = (_usbd_dev.ep_status[epnum][dir].busy == 0) && (_usbd_dev.ep_status[epnum][dir].claimed == 0);
   if (ret)
   {
     _usbd_dev.ep_status[epnum][dir].claimed = 1;