kgdb expects poll function to return immediately and returning NO_POLL_CHAR when no character is available.

Fixes: f5316b4aea024 ("kgdb,8250,pl011: Return immediately from console poll") Cc: Jason Wessel jason.wessel@windriver.com Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr --- drivers/tty/serial/cpm_uart/cpm_uart_core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c index cd3f3fc4e0a5..280acc4dfa90 100644 --- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c +++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c @@ -1093,8 +1093,8 @@ static int poll_wait_key(char *obuf, struct uart_cpm_port *pinfo) /* Get the address of the host memory buffer. */ bdp = pinfo->rx_cur; - while (bdp->cbd_sc & BD_SC_EMPTY) - ; + if (bdp->cbd_sc & BD_SC_EMPTY) + return NO_POLL_CHAR;

/* If the buffer address is in the CPM DPRAM, don't * convert it. @@ -1129,7 +1129,11 @@ static int cpm_get_poll_char(struct uart_port *port) poll_chars = 0; } if (poll_chars <= 0) { - poll_chars = poll_wait_key(poll_buf, pinfo); + int ret = poll_wait_key(poll_buf, pinfo); + + if (ret == NO_POLL_CHAR) + return ret; + poll_chars = ret; pollp = poll_buf; } poll_chars--;