tty: hvc: udbg_hvc: retry putc on -EAGAIN
hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN
when the underlying hcall returns a "busy" status, but udbg_hvc_putc()
doesn't handle this. When using xmon on a PowerVM guest, this can
result in incomplete or garbled output when printing relatively large
amounts of data quickly, such as when dumping the kernel log buffer.
Call again on -EAGAIN.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210514214422.3019105-1-nathanl@linux.ibm.com
diff --git a/drivers/tty/hvc/hvc_vio.c b/drivers/tty/hvc/hvc_vio.c
index 798f27f..72b11aa7e 100644
--- a/drivers/tty/hvc/hvc_vio.c
+++ b/drivers/tty/hvc/hvc_vio.c
@@ -249,7 +249,7 @@ static void udbg_hvc_putc(char c)
count = hvterm_hvsi_put_chars(0, &c, 1);
break;
}
- } while(count == 0);
+ } while (count == 0 || count == -EAGAIN);
}
static int udbg_hvc_getc_poll(void)
