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| author | Hendrik Brueckner <brueckner@linux.vnet.ibm.com> | 2011-07-05 21:50:18 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-08-04 21:58:41 -0700 |
| commit | 9f78aa15dc4b47ca0bc6269c7c0e4f2345a66580 (patch) | |
| tree | 805b9cde463755fc54ddf4070aa996fd564db7b0 | |
| parent | dc96c18103480c2aacb6c4c7fbb9400e29c604c9 (diff) | |
| download | lwn-9f78aa15dc4b47ca0bc6269c7c0e4f2345a66580.tar.gz lwn-9f78aa15dc4b47ca0bc6269c7c0e4f2345a66580.zip | |
hvc_console: Improve tty/console put_chars handling
commit 8c2381af0d3ef62a681dac5a141b6dabb27bf2e1 upstream.
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 <brueckner@linux.vnet.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/tty/hvc/hvc_console.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index e9cba13ee800..aa84555048ba 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -163,8 +163,10 @@ static void hvc_console_print(struct console *co, const char *b, } 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 *hp) 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; } |