kernel_optimize_test/arch/xtensa/platforms/iss/console.c
Max Filippov efefbcc500 xtensa: ISS: fix timer_lock usage in rs_open
This fixes the following lockdep splat:

[   66.460000] =================================
[   66.460000] [ INFO: inconsistent lock state ]
[   66.460000] 3.9.0-rc5-00161-ga48dd49 #4 Not tainted
[   66.460000] ---------------------------------
[   66.460000] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[   66.460000] swapper/1 [HC0[0]:SC1[1]:HE1:SE0] takes:
[   66.460000]  (timer_lock){+.?...}, at: [<d0006cde>] rs_poll+0x12/0xdc
[   66.460000] {SOFTIRQ-ON-W} state was registered at:
[   66.460000]   [<d00421f0>] lock_acquire+0xec/0x13c
[   66.460000]   [<d01ea036>] _raw_spin_lock+0x3a/0x84
[   66.460000]   [<d0006c8c>] rs_open+0x18/0x58
[   66.460000]   [<d0139ea2>] tty_open+0x262/0x3cc
[   66.460000]   [<d00942e0>] chrdev_open+0x8c/0xe0
[   66.460000]   [<d00907b2>] do_dentry_open$isra$16+0x10e/0x190
[   66.460000]   [<d0091141>] finish_open+0x39/0x48
[   66.460000]   [<d009a0b4>] do_last$isra$34+0x6c4/0x824
[   66.460000]   [<d009a27a>] path_openat+0x66/0x310
[   66.460000]   [<d009a53a>] do_filp_open+0x16/0x44
[   66.460000]   [<d0091445>] do_sys_open+0xd5/0x13c
[   66.460000]   [<d00914be>] sys_open+0x12/0x18
[   66.460000]   [<d0413ffc>] kernel_init_freeable+0xe4/0x12c
[   66.460000]   [<d01e2a9c>] kernel_init+0xc/0x9c
[   66.460000]   [<d00044fc>] ret_from_kernel_thread+0x8/0xc
[   66.460000] irq event stamp: 132542
[   66.460000] hardirqs last  enabled at (132542): [<d01ea2ec>] _raw_spin_unlock_irq+0x30/0x44
[   66.460000] hardirqs last disabled at (132541): [<d01ea11e>] _raw_spin_lock_irq+0xe/0x8c
[   66.460000] softirqs last  enabled at (132234): [<d0017d32>] __do_softirq+0x216/0x2a4
[   66.460000] softirqs last disabled at (132539): [<d0018024>] irq_exit+0x38/0x40
[   66.460000]
[   66.460000] other info that might help us debug this:
[   66.460000]  Possible unsafe locking scenario:
[   66.460000]
[   66.460000]        CPU0
[   66.460000]        ----
[   66.460000]   lock(timer_lock);
[   66.460000]   <Interrupt>
[   66.460000]     lock(timer_lock);
[   66.460000]
[   66.460000]  *** DEADLOCK ***
[   66.460000]
[   66.460000] 1 lock held by swapper/1:
[   66.460000]  #0:  (((&serial_timer))){+.-...}, at: [<d001c65c>] call_timer_fn+0x0/0x1f0
[   66.460000]
Stack: d7c2fac0 00000018 00000004 00000001 d7c2faa0 00000004 00000006 d7c2fa90
       9003e87c d7c2fae0 d7c30000 d025a87c 00000001 0000000f 00000000 d7c2fac0
       9004005d d7c2fb10 d7c30000 d7c30338 00000001 00000001 00000000 d7c30338
[   66.460000] Call Trace:
[   66.460000]  [<d01e4f93>] print_usage_bug$part$26+0x1c3/0x1c8
[   66.460000]  [<d003e87c>] mark_lock+0x2b4/0x440
[   66.460000]  [<d004005d>] __lock_acquire+0x54d/0x16c4
[   66.460000]  [<d00421f0>] lock_acquire+0xec/0x13c
[   66.460000]  [<d01ea036>] _raw_spin_lock+0x3a/0x84
[   66.460000]  [<d0006cde>] rs_poll+0x12/0xdc
[   66.460000]  [<d001c71a>] call_timer_fn+0xbe/0x1f0
[   66.460000]  [<d001cd90>] run_timer_softirq+0x198/0x1f4
[   66.460000]  [<d0017c30>] __do_softirq+0x114/0x2a4
[   66.460000]  [<d0018024>] irq_exit+0x38/0x40
[   66.460000]  [<d00046c0>] do_IRQ+0x44/0x48
[   66.460000]  [<d0005c58>] do_interrupt+0x4c/0x54
[   66.460000]  [<d0003c80>] common_exception_return+0x0/0x5c
[   66.460000]  [<d006682c>] free_pcppages_bulk+0x254/0x308
[   66.460000]

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
2013-05-09 01:07:11 -07:00

274 lines
6.3 KiB
C

/*
* arch/xtensa/platforms/iss/console.c
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001-2005 Tensilica Inc.
* Authors Christian Zankel, Joe Taylor
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/major.h>
#include <linux/param.h>
#include <linux/seq_file.h>
#include <linux/serial.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <platform/simcall.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#ifdef SERIAL_INLINE
#define _INLINE_ inline
#endif
#define SERIAL_MAX_NUM_LINES 1
#define SERIAL_TIMER_VALUE (HZ / 10)
static struct tty_driver *serial_driver;
static struct tty_port serial_port;
static struct timer_list serial_timer;
static DEFINE_SPINLOCK(timer_lock);
static char *serial_version = "0.1";
static char *serial_name = "ISS serial driver";
/*
* This routine is called whenever a serial port is opened. It
* enables interrupts for a serial port, linking in its async structure into
* the IRQ chain. It also performs the serial-specific
* initialization for the tty structure.
*/
static void rs_poll(unsigned long);
static int rs_open(struct tty_struct *tty, struct file * filp)
{
tty->port = &serial_port;
spin_lock_bh(&timer_lock);
if (tty->count == 1) {
setup_timer(&serial_timer, rs_poll,
(unsigned long)&serial_port);
mod_timer(&serial_timer, jiffies + SERIAL_TIMER_VALUE);
}
spin_unlock_bh(&timer_lock);
return 0;
}
/*
* ------------------------------------------------------------
* iss_serial_close()
*
* This routine is called when the serial port gets closed. First, we
* wait for the last remaining data to be sent. Then, we unlink its
* async structure from the interrupt chain if necessary, and we free
* that IRQ if nothing is left in the chain.
* ------------------------------------------------------------
*/
static void rs_close(struct tty_struct *tty, struct file * filp)
{
spin_lock_bh(&timer_lock);
if (tty->count == 1)
del_timer_sync(&serial_timer);
spin_unlock_bh(&timer_lock);
}
static int rs_write(struct tty_struct * tty,
const unsigned char *buf, int count)
{
/* see drivers/char/serialX.c to reference original version */
simc_write(1, buf, count);
return count;
}
static void rs_poll(unsigned long priv)
{
struct tty_port *port = (struct tty_port *)priv;
int i = 0;
unsigned char c;
spin_lock(&timer_lock);
while (simc_poll(0)) {
simc_read(0, &c, 1);
tty_insert_flip_char(port, c, TTY_NORMAL);
i++;
}
if (i)
tty_flip_buffer_push(port);
mod_timer(&serial_timer, jiffies + SERIAL_TIMER_VALUE);
spin_unlock(&timer_lock);
}
static int rs_put_char(struct tty_struct *tty, unsigned char ch)
{
return rs_write(tty, &ch, 1);
}
static void rs_flush_chars(struct tty_struct *tty)
{
}
static int rs_write_room(struct tty_struct *tty)
{
/* Let's say iss can always accept 2K characters.. */
return 2 * 1024;
}
static int rs_chars_in_buffer(struct tty_struct *tty)
{
/* the iss doesn't buffer characters */
return 0;
}
static void rs_hangup(struct tty_struct *tty)
{
/* Stub, once again.. */
}
static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
/* Stub, once again.. */
}
static int rs_proc_show(struct seq_file *m, void *v)
{
seq_printf(m, "serinfo:1.0 driver:%s\n", serial_version);
return 0;
}
static int rs_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, rs_proc_show, NULL);
}
static const struct file_operations rs_proc_fops = {
.owner = THIS_MODULE,
.open = rs_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static const struct tty_operations serial_ops = {
.open = rs_open,
.close = rs_close,
.write = rs_write,
.put_char = rs_put_char,
.flush_chars = rs_flush_chars,
.write_room = rs_write_room,
.chars_in_buffer = rs_chars_in_buffer,
.hangup = rs_hangup,
.wait_until_sent = rs_wait_until_sent,
.proc_fops = &rs_proc_fops,
};
int __init rs_init(void)
{
tty_port_init(&serial_port);
serial_driver = alloc_tty_driver(SERIAL_MAX_NUM_LINES);
printk ("%s %s\n", serial_name, serial_version);
/* Initialize the tty_driver structure */
serial_driver->driver_name = "iss_serial";
serial_driver->name = "ttyS";
serial_driver->major = TTY_MAJOR;
serial_driver->minor_start = 64;
serial_driver->type = TTY_DRIVER_TYPE_SERIAL;
serial_driver->subtype = SERIAL_TYPE_NORMAL;
serial_driver->init_termios = tty_std_termios;
serial_driver->init_termios.c_cflag =
B9600 | CS8 | CREAD | HUPCL | CLOCAL;
serial_driver->flags = TTY_DRIVER_REAL_RAW;
tty_set_operations(serial_driver, &serial_ops);
tty_port_link_device(&serial_port, serial_driver, 0);
if (tty_register_driver(serial_driver))
panic("Couldn't register serial driver\n");
return 0;
}
static __exit void rs_exit(void)
{
int error;
if ((error = tty_unregister_driver(serial_driver)))
printk("ISS_SERIAL: failed to unregister serial driver (%d)\n",
error);
put_tty_driver(serial_driver);
tty_port_destroy(&serial_port);
}
/* We use `late_initcall' instead of just `__initcall' as a workaround for
* the fact that (1) simcons_tty_init can't be called before tty_init,
* (2) tty_init is called via `module_init', (3) if statically linked,
* module_init == device_init, and (4) there's no ordering of init lists.
* We can do this easily because simcons is always statically linked, but
* other tty drivers that depend on tty_init and which must use
* `module_init' to declare their init routines are likely to be broken.
*/
late_initcall(rs_init);
#ifdef CONFIG_SERIAL_CONSOLE
static void iss_console_write(struct console *co, const char *s, unsigned count)
{
int len = strlen(s);
if (s != 0 && *s != 0)
simc_write(1, s, count < len ? count : len);
}
static struct tty_driver* iss_console_device(struct console *c, int *index)
{
*index = c->index;
return serial_driver;
}
static struct console sercons = {
.name = "ttyS",
.write = iss_console_write,
.device = iss_console_device,
.flags = CON_PRINTBUFFER,
.index = -1
};
static int __init iss_console_init(void)
{
register_console(&sercons);
return 0;
}
console_initcall(iss_console_init);
#endif /* CONFIG_SERIAL_CONSOLE */