From: David Brownell <david-b@pacbell.net>
Fixes "Badness in local_bh_enable at kernel/softirq.c:121"
This driver calls ppp rx functions in hard irq context, which is deadlocky.
Those functions expect to run in softirq context.
25-akpm/drivers/usb/class/cdc-acm.c | 42 +++++++++++++++++++++++++-----------
1 files changed, 30 insertions(+), 12 deletions(-)
diff -puN drivers/usb/class/cdc-acm.c~cdc-acm-softirq-rx drivers/usb/class/cdc-acm.c
--- 25/drivers/usb/class/cdc-acm.c~cdc-acm-softirq-rx Fri Oct 31 13:54:23 2003
+++ 25-akpm/drivers/usb/class/cdc-acm.c Fri Oct 31 13:54:23 2003
@@ -1,5 +1,5 @@
/*
- * acm.c Version 0.22
+ * cdc-acm.c
*
* Copyright (c) 1999 Armin Fuerst <fuerst@in.tum.de>
* Copyright (c) 1999 Pavel Machek <pavel@suse.cz>
@@ -26,6 +26,7 @@
* v0.21 - revert to probing on device for devices with multiple configs
* v0.22 - probe only the control interface. if usbcore doesn't choose the
* config we want, sysadmin changes bConfigurationValue in sysfs.
+ * v0.23 - use softirq for rx processing, as needed by tty layer
*/
/*
@@ -44,6 +45,8 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
+#undef DEBUG
+
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
@@ -54,14 +57,13 @@
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
-#undef DEBUG
#include <linux/usb.h>
#include <asm/byteorder.h>
/*
* Version Information
*/
-#define DRIVER_VERSION "v0.21"
+#define DRIVER_VERSION "v0.23"
#define DRIVER_AUTHOR "Armin Fuerst, Pavel Machek, Johannes Erdfelt, Vojtech Pavlik"
#define DRIVER_DESC "USB Abstract Control Model driver for USB modems and ISDN adapters"
@@ -146,7 +148,8 @@ struct acm {
struct tty_struct *tty; /* the corresponding tty */
struct urb *ctrlurb, *readurb, *writeurb; /* urbs */
struct acm_line line; /* line coding (bits, stop, parity) */
- struct work_struct work; /* work queue entry for line discipline waking up */
+ struct work_struct work; /* work queue entry for line discipline waking up */
+ struct tasklet_struct bh; /* rx processing */
unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */
unsigned int ctrlout; /* output control lines (DTR, RTS) */
unsigned int writesize; /* max packet size for the output bulk endpoint */
@@ -184,9 +187,10 @@ static int acm_ctrl_msg(struct acm *acm,
#define acm_send_break(acm, ms) acm_ctrl_msg(acm, ACM_REQ_SEND_BREAK, ms, NULL, 0)
/*
- * Interrupt handler for various ACM control events
+ * Interrupt handlers for various ACM device responses
*/
+/* control interface reports status changes with "interrupt" transfers */
static void acm_ctrl_irq(struct urb *urb, struct pt_regs *regs)
{
struct acm *acm = urb->context;
@@ -251,20 +255,30 @@ exit:
__FUNCTION__, status);
}
+/* data interface returns incoming bytes, or we got unthrottled */
static void acm_read_bulk(struct urb *urb, struct pt_regs *regs)
{
struct acm *acm = urb->context;
- struct tty_struct *tty = acm->tty;
- unsigned char *data = urb->transfer_buffer;
- int i = 0;
if (!ACM_READY(acm))
return;
if (urb->status)
- dbg("nonzero read bulk status received: %d", urb->status);
+ dev_dbg(&acm->data->dev, "bulk rx status %d\n", urb->status);
+
+ /* calling tty_flip_buffer_push() in_irq() isn't allowed */
+ tasklet_schedule(&acm->bh);
+}
+
+static void acm_rx_tasklet(unsigned long _acm)
+{
+ struct acm *acm = (void *)_acm;
+ struct urb *urb = acm->readurb;
+ struct tty_struct *tty = acm->tty;
+ unsigned char *data = urb->transfer_buffer;
+ int i = 0;
- if (!urb->status && !acm->throttle) {
+ if (urb->actual_length > 0 && !acm->throttle) {
for (i = 0; i < urb->actual_length && !acm->throttle; i++) {
/* if we insert more than TTY_FLIPBUF_SIZE characters,
* we drop them. */
@@ -285,10 +299,12 @@ static void acm_read_bulk(struct urb *ur
urb->actual_length = 0;
urb->dev = acm->dev;
- if (usb_submit_urb(urb, GFP_ATOMIC))
- dbg("failed resubmitting read urb");
+ i = usb_submit_urb(urb, GFP_ATOMIC);
+ if (i)
+ dev_dbg(&acm->data->dev, "bulk rx resubmit %d\n", i);
}
+/* data interface wrote those outgoing bytes */
static void acm_write_bulk(struct urb *urb, struct pt_regs *regs)
{
struct acm *acm = (struct acm *)urb->context;
@@ -621,6 +637,8 @@ static int acm_probe (struct usb_interfa
acm->minor = minor;
acm->dev = dev;
+ acm->bh.func = acm_rx_tasklet;
+ acm->bh.data = (unsigned long) acm;
INIT_WORK(&acm->work, acm_softint, acm);
if (!(buf = kmalloc(ctrlsize + readsize + acm->writesize, GFP_KERNEL))) {
_