From: Hendrik Brueckner <brueck...@linux.vnet.ibm.com>
Currently, the hvc_console_print() function drops console output if the
hvc backend's put_chars() returns 0. This patch changes this behavior
to allow a retry through returning -EAGAIN.
This change also affects the hvc_push() function. Both functions are
changed to handle -EAGAIN and to retry the put_chars() operation.
If a hvc backend returns -EAGAIN, the retry handling differs:
- hvc_console_print() spins to write the complete console output.
- hvc_push() behaves the same way as for returning 0.
Now hvc backends can indirectly control the way how console output is
handled through the hvc console layer.
Signed-off-by: Hendrik Brueckner <brueck...@linux.vnet.ibm.com>
Acked-by: Anton Blanchard <an...@samba.org>
Cc: <sta...@kernel.org>
---
Index: linux-powerpc/drivers/tty/hvc/hvc_console.c
===================================================================
--- linux-powerpc.orig/drivers/tty/hvc/hvc_console.c 2011-07-06
17:10:51.288360541 +1000
+++ linux-powerpc/drivers/tty/hvc/hvc_console.c 2011-07-06 17:11:16.398794913
+1000
@@ -163,8 +163,10 @@ static void hvc_console_print(struct con
} else {
r = cons_ops[index]->put_chars(vtermnos[index], c, i);
if (r <= 0) {
- /* throw away chars on error */
- i = 0;
+ /* throw away characters on error
+ * but spin in case of -EAGAIN */
+ if (r != -EAGAIN)
+ i = 0;
} else if (r > 0) {
i -= r;
if (i > 0)
@@ -448,7 +450,7 @@ static int hvc_push(struct hvc_struct *h
n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
if (n <= 0) {
- if (n == 0) {
+ if (n == 0 || n == -EAGAIN) {
hp->do_wakeup = 1;
return 0;
}
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