The patch titled
usb-serial: regression fix to move sysrq from hot path
has been removed from the -mm tree. Its filename was
usb-serial-regression-fix-to-move-sysrq-from-hot-path.patch
This patch was dropped because an alternative patch was merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: usb-serial: regression fix to move sysrq from hot path
From: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
A performance regression was introduced by commit
98fcb5f78165b8a3d93870ad7afd4d9ebbb8b43a ("USB: serial:
usb_debug,usb_generic_serial: implement sysrq and serial break").
The sysrq handling should only get executed if the attached usb serial
device is acting as a serial system console. A serial system console has
a very low input throughput vs a 3g usb modem which pushes bytes through
the same interface at a high rate.
Entire strings of output can be processed via the tty input when the
device is not a console.
Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/usb/serial/generic.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff -puN drivers/usb/serial/generic.c~usb-serial-regression-fix-to-move-sysrq-from-hot-path drivers/usb/serial/generic.c
--- a/drivers/usb/serial/generic.c~usb-serial-regression-fix-to-move-sysrq-from-hot-path
+++ a/drivers/usb/serial/generic.c
@@ -425,11 +425,19 @@ static void flush_and_resubmit_read_urb(
goto done;
/* Push data to tty */
- for (i = 0; i < urb->actual_length; i++, ch++) {
- if (!usb_serial_handle_sysrq_char(port, *ch))
- tty_insert_flip_char(tty, *ch, TTY_NORMAL);
+ if (port->console) {
+ for (i = 0; i < urb->actual_length; i++, ch++) {
+ if (!usb_serial_handle_sysrq_char(port, *ch))
+ tty_insert_flip_char(tty, *ch, TTY_NORMAL);
+ }
+ tty_flip_buffer_push(tty);
+ } else if (urb->actual_length) {
+ i = tty_buffer_request_room(tty, urb->actual_length);
+ if (i) {
+ tty_insert_flip_string(tty, urb->transfer_buffer, i);
+ tty_flip_buffer_push(tty);
+ }
}
- tty_flip_buffer_push(tty);
tty_kref_put(tty);
done:
usb_serial_generic_resubmit_read_urb(port, GFP_ATOMIC);
_
Patches currently in -mm which might be from jason.wessel@xxxxxxxxxxxxx are
linux-next.patch
usb-serial-regression-fix-to-move-sysrq-from-hot-path.patch
frv-duplicate-output_buffer-of-e03.patch
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