[PATCH 1/4] cdc-acm: Fix long standing abuse of tty->low_latency

[Alan Cox]

ACM sets the low latency flag but calls the flip buffer routines from IRQ
context which isn't permitted (and as of 2.6.29 causes a warning hence this
one was caught)

Fortunatelt ACM doesn't need to set this flag in the first place as it only
set it to work around problems in ancient (pre tty flip rewrite) kernels.

Reported-by: Chuck Ebbert <cebbert@xxxxxxxxxx>
Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
---

 drivers/usb/class/cdc-acm.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)


diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 869d47c..0a69c09 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -546,10 +546,6 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 	tty->driver_data = acm;
 	acm->tty = tty;
 
-	/* force low_latency on so that our tty_push actually forces the data through,
-	   otherwise it is scheduled, and with high data rates data can get lost. */
-	tty->low_latency = 1;
-
 	if (usb_autopm_get_interface(acm->control) < 0)
 		goto early_bail;
 	else

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