4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christophe Leroy <christophe.leroy@xxxxxx>
commit be28c1e3ca29887e207f0cbcd294cefe5074bab6 upstream.
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@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/cpm_uart/cpm_uart_core.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
@@ -1068,8 +1068,8 @@ static int poll_wait_key(char *obuf, str
/* 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.
@@ -1104,7 +1104,11 @@ static int cpm_get_poll_char(struct uart
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--;
