diff options
| author | Marti Bolivar <mbolivar@leaflabs.com> | 2012-08-04 00:33:32 -0400 |
|---|---|---|
| committer | Marti Bolivar <mbolivar@leaflabs.com> | 2012-08-04 00:33:32 -0400 |
| commit | b642f7b095b2c9324281f2a7f929314ddbafe17c (patch) | |
| tree | 9397c300956a4f7945822241a4d70577c1837b9a | |
| parent | 6788dff2e0ba8a548b0a91b78c04031a4fc5df54 (diff) | |
usb_cdcacm: Set endpoint to NAK before checking byte count.
Fixes an (admittedly very unlikely) race condition.
Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>
| -rw-r--r-- | libmaple/usb/stm32f1/usb_cdcacm.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/libmaple/usb/stm32f1/usb_cdcacm.c b/libmaple/usb/stm32f1/usb_cdcacm.c index 07cf9c4..2a942e5 100644 --- a/libmaple/usb/stm32f1/usb_cdcacm.c +++ b/libmaple/usb/stm32f1/usb_cdcacm.c @@ -540,11 +540,11 @@ static void vcomDataTxCb(void) { } static void vcomDataRxCb(void) { - /* This following is safe since we set the RX endpoint to NAK - * after each data packet received, and only set it to VALID when - * all bytes have been read. */ - n_unread_bytes = usb_get_ep_rx_count(USB_CDCACM_RX_ENDP); usb_set_ep_rx_stat(USB_CDCACM_RX_ENDP, USB_EP_STAT_RX_NAK); + n_unread_bytes = usb_get_ep_rx_count(USB_CDCACM_RX_ENDP); + /* This copy won't overwrite unread bytes, since we've set the RX + * endpoint to NAK, and will only set it to VALID when all bytes + * have been read. */ usb_copy_from_pma((uint8*)vcomBufferRx, n_unread_bytes, USB_CDCACM_RX_ADDR); |