From: Henry Gebhardt <gebhardt@astro.uni-tuebingen.de>
Date: Wed, 4 Nov 2009 10:19:28 +0000 (+0100)
Subject: USB: cdc_acm: Fix race condition when opening tty
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=18a77b5d237a67d2c621a46f5271a3b51da1b380;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

USB: cdc_acm: Fix race condition when opening tty

If acm_rx_tasklet() gets called before tty_port_block_til_ready()
returns, then bulk IN urbs may not be sent. This fixes it.

Signed-off-by: Henry Gebhardt <gebhardt@astro.uni-tuebingen.de>
Acked-by: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e3861b21e776..b72fa49eb257 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -609,9 +609,9 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 
 	acm->throttle = 0;
 
-	tasklet_schedule(&acm->urb_task);
 	set_bit(ASYNCB_INITIALIZED, &acm->port.flags);
 	rv = tty_port_block_til_ready(&acm->port, tty, filp);
+	tasklet_schedule(&acm->urb_task);
 done:
 	mutex_unlock(&acm->mutex);
 err_out: