linux/arch/um/drivers/line.c
Anton Ivanov ff6a17989c Epoll based IRQ controller
1. Removes the need to walk the IRQ/Device list to determine
who triggered the IRQ.
2. Improves scalability (up to several times performance
improvement for cases with 10s of devices).
3. Improves UML baseline IO performance for one disk + one NIC
use case by up to 10%.
4. Introduces write poll triggered IRQs.
5. Prerequisite for introducing high performance mmesg family
of functions in network IO.
6. Fixes RNG shutdown which was leaking a file descriptor

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-02-19 19:38:51 +01:00

770 lines
16 KiB
C

/*
* Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/irqreturn.h>
#include <linux/kd.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include "chan.h"
#include <irq_kern.h>
#include <irq_user.h>
#include <kern_util.h>
#include <os.h>
#define LINE_BUFSIZE 4096
static irqreturn_t line_interrupt(int irq, void *data)
{
struct chan *chan = data;
struct line *line = chan->line;
if (line)
chan_interrupt(line, irq);
return IRQ_HANDLED;
}
/*
* Returns the free space inside the ring buffer of this line.
*
* Should be called while holding line->lock (this does not modify data).
*/
static int write_room(struct line *line)
{
int n;
if (line->buffer == NULL)
return LINE_BUFSIZE - 1;
/* This is for the case where the buffer is wrapped! */
n = line->head - line->tail;
if (n <= 0)
n += LINE_BUFSIZE; /* The other case */
return n - 1;
}
int line_write_room(struct tty_struct *tty)
{
struct line *line = tty->driver_data;
unsigned long flags;
int room;
spin_lock_irqsave(&line->lock, flags);
room = write_room(line);
spin_unlock_irqrestore(&line->lock, flags);
return room;
}
int line_chars_in_buffer(struct tty_struct *tty)
{
struct line *line = tty->driver_data;
unsigned long flags;
int ret;
spin_lock_irqsave(&line->lock, flags);
/* write_room subtracts 1 for the needed NULL, so we readd it.*/
ret = LINE_BUFSIZE - (write_room(line) + 1);
spin_unlock_irqrestore(&line->lock, flags);
return ret;
}
/*
* This copies the content of buf into the circular buffer associated with
* this line.
* The return value is the number of characters actually copied, i.e. the ones
* for which there was space: this function is not supposed to ever flush out
* the circular buffer.
*
* Must be called while holding line->lock!
*/
static int buffer_data(struct line *line, const char *buf, int len)
{
int end, room;
if (line->buffer == NULL) {
line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
if (line->buffer == NULL) {
printk(KERN_ERR "buffer_data - atomic allocation "
"failed\n");
return 0;
}
line->head = line->buffer;
line->tail = line->buffer;
}
room = write_room(line);
len = (len > room) ? room : len;
end = line->buffer + LINE_BUFSIZE - line->tail;
if (len < end) {
memcpy(line->tail, buf, len);
line->tail += len;
}
else {
/* The circular buffer is wrapping */
memcpy(line->tail, buf, end);
buf += end;
memcpy(line->buffer, buf, len - end);
line->tail = line->buffer + len - end;
}
return len;
}
/*
* Flushes the ring buffer to the output channels. That is, write_chan is
* called, passing it line->head as buffer, and an appropriate count.
*
* On exit, returns 1 when the buffer is empty,
* 0 when the buffer is not empty on exit,
* and -errno when an error occurred.
*
* Must be called while holding line->lock!*/
static int flush_buffer(struct line *line)
{
int n, count;
if ((line->buffer == NULL) || (line->head == line->tail))
return 1;
if (line->tail < line->head) {
/* line->buffer + LINE_BUFSIZE is the end of the buffer! */
count = line->buffer + LINE_BUFSIZE - line->head;
n = write_chan(line->chan_out, line->head, count,
line->driver->write_irq);
if (n < 0)
return n;
if (n == count) {
/*
* We have flushed from ->head to buffer end, now we
* must flush only from the beginning to ->tail.
*/
line->head = line->buffer;
} else {
line->head += n;
return 0;
}
}
count = line->tail - line->head;
n = write_chan(line->chan_out, line->head, count,
line->driver->write_irq);
if (n < 0)
return n;
line->head += n;
return line->head == line->tail;
}
void line_flush_buffer(struct tty_struct *tty)
{
struct line *line = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&line->lock, flags);
flush_buffer(line);
spin_unlock_irqrestore(&line->lock, flags);
}
/*
* We map both ->flush_chars and ->put_char (which go in pair) onto
* ->flush_buffer and ->write. Hope it's not that bad.
*/
void line_flush_chars(struct tty_struct *tty)
{
line_flush_buffer(tty);
}
int line_put_char(struct tty_struct *tty, unsigned char ch)
{
return line_write(tty, &ch, sizeof(ch));
}
int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
{
struct line *line = tty->driver_data;
unsigned long flags;
int n, ret = 0;
spin_lock_irqsave(&line->lock, flags);
if (line->head != line->tail)
ret = buffer_data(line, buf, len);
else {
n = write_chan(line->chan_out, buf, len,
line->driver->write_irq);
if (n < 0) {
ret = n;
goto out_up;
}
len -= n;
ret += n;
if (len > 0)
ret += buffer_data(line, buf + n, len);
}
out_up:
spin_unlock_irqrestore(&line->lock, flags);
return ret;
}
void line_set_termios(struct tty_struct *tty, struct ktermios * old)
{
/* nothing */
}
void line_throttle(struct tty_struct *tty)
{
struct line *line = tty->driver_data;
deactivate_chan(line->chan_in, line->driver->read_irq);
line->throttled = 1;
}
void line_unthrottle(struct tty_struct *tty)
{
struct line *line = tty->driver_data;
line->throttled = 0;
chan_interrupt(line, line->driver->read_irq);
/*
* Maybe there is enough stuff pending that calling the interrupt
* throttles us again. In this case, line->throttled will be 1
* again and we shouldn't turn the interrupt back on.
*/
if (!line->throttled)
reactivate_chan(line->chan_in, line->driver->read_irq);
}
static irqreturn_t line_write_interrupt(int irq, void *data)
{
struct chan *chan = data;
struct line *line = chan->line;
int err;
/*
* Interrupts are disabled here because genirq keep irqs disabled when
* calling the action handler.
*/
spin_lock(&line->lock);
err = flush_buffer(line);
if (err == 0) {
spin_unlock(&line->lock);
return IRQ_NONE;
} else if (err < 0) {
line->head = line->buffer;
line->tail = line->buffer;
}
spin_unlock(&line->lock);
tty_port_tty_wakeup(&line->port);
return IRQ_HANDLED;
}
int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
{
const struct line_driver *driver = line->driver;
int err = 0;
if (input)
err = um_request_irq(driver->read_irq, fd, IRQ_READ,
line_interrupt, IRQF_SHARED,
driver->read_irq_name, data);
if (err)
return err;
if (output)
err = um_request_irq(driver->write_irq, fd, IRQ_NONE,
line_write_interrupt, IRQF_SHARED,
driver->write_irq_name, data);
return err;
}
static int line_activate(struct tty_port *port, struct tty_struct *tty)
{
int ret;
struct line *line = tty->driver_data;
ret = enable_chan(line);
if (ret)
return ret;
if (!line->sigio) {
chan_enable_winch(line->chan_out, port);
line->sigio = 1;
}
chan_window_size(line, &tty->winsize.ws_row,
&tty->winsize.ws_col);
return 0;
}
static void unregister_winch(struct tty_struct *tty);
static void line_destruct(struct tty_port *port)
{
struct tty_struct *tty = tty_port_tty_get(port);
struct line *line = tty->driver_data;
if (line->sigio) {
unregister_winch(tty);
line->sigio = 0;
}
}
static const struct tty_port_operations line_port_ops = {
.activate = line_activate,
.destruct = line_destruct,
};
int line_open(struct tty_struct *tty, struct file *filp)
{
struct line *line = tty->driver_data;
return tty_port_open(&line->port, tty, filp);
}
int line_install(struct tty_driver *driver, struct tty_struct *tty,
struct line *line)
{
int ret;
ret = tty_standard_install(driver, tty);
if (ret)
return ret;
tty->driver_data = line;
return 0;
}
void line_close(struct tty_struct *tty, struct file * filp)
{
struct line *line = tty->driver_data;
tty_port_close(&line->port, tty, filp);
}
void line_hangup(struct tty_struct *tty)
{
struct line *line = tty->driver_data;
tty_port_hangup(&line->port);
}
void close_lines(struct line *lines, int nlines)
{
int i;
for(i = 0; i < nlines; i++)
close_chan(&lines[i]);
}
int setup_one_line(struct line *lines, int n, char *init,
const struct chan_opts *opts, char **error_out)
{
struct line *line = &lines[n];
struct tty_driver *driver = line->driver->driver;
int err = -EINVAL;
if (line->port.count) {
*error_out = "Device is already open";
goto out;
}
if (!strcmp(init, "none")) {
if (line->valid) {
line->valid = 0;
kfree(line->init_str);
tty_unregister_device(driver, n);
parse_chan_pair(NULL, line, n, opts, error_out);
err = 0;
}
} else {
char *new = kstrdup(init, GFP_KERNEL);
if (!new) {
*error_out = "Failed to allocate memory";
return -ENOMEM;
}
if (line->valid) {
tty_unregister_device(driver, n);
kfree(line->init_str);
}
line->init_str = new;
line->valid = 1;
err = parse_chan_pair(new, line, n, opts, error_out);
if (!err) {
struct device *d = tty_port_register_device(&line->port,
driver, n, NULL);
if (IS_ERR(d)) {
*error_out = "Failed to register device";
err = PTR_ERR(d);
parse_chan_pair(NULL, line, n, opts, error_out);
}
}
if (err) {
line->init_str = NULL;
line->valid = 0;
kfree(new);
}
}
out:
return err;
}
/*
* Common setup code for both startup command line and mconsole initialization.
* @lines contains the array (of size @num) to modify;
* @init is the setup string;
* @error_out is an error string in the case of failure;
*/
int line_setup(char **conf, unsigned int num, char **def,
char *init, char *name)
{
char *error;
if (*init == '=') {
/*
* We said con=/ssl= instead of con#=, so we are configuring all
* consoles at once.
*/
*def = init + 1;
} else {
char *end;
unsigned n = simple_strtoul(init, &end, 0);
if (*end != '=') {
error = "Couldn't parse device number";
goto out;
}
if (n >= num) {
error = "Device number out of range";
goto out;
}
conf[n] = end + 1;
}
return 0;
out:
printk(KERN_ERR "Failed to set up %s with "
"configuration string \"%s\" : %s\n", name, init, error);
return -EINVAL;
}
int line_config(struct line *lines, unsigned int num, char *str,
const struct chan_opts *opts, char **error_out)
{
char *end;
int n;
if (*str == '=') {
*error_out = "Can't configure all devices from mconsole";
return -EINVAL;
}
n = simple_strtoul(str, &end, 0);
if (*end++ != '=') {
*error_out = "Couldn't parse device number";
return -EINVAL;
}
if (n >= num) {
*error_out = "Device number out of range";
return -EINVAL;
}
return setup_one_line(lines, n, end, opts, error_out);
}
int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
int size, char **error_out)
{
struct line *line;
char *end;
int dev, n = 0;
dev = simple_strtoul(name, &end, 0);
if ((*end != '\0') || (end == name)) {
*error_out = "line_get_config failed to parse device number";
return 0;
}
if ((dev < 0) || (dev >= num)) {
*error_out = "device number out of range";
return 0;
}
line = &lines[dev];
if (!line->valid)
CONFIG_CHUNK(str, size, n, "none", 1);
else {
struct tty_struct *tty = tty_port_tty_get(&line->port);
if (tty == NULL) {
CONFIG_CHUNK(str, size, n, line->init_str, 1);
} else {
n = chan_config_string(line, str, size, error_out);
tty_kref_put(tty);
}
}
return n;
}
int line_id(char **str, int *start_out, int *end_out)
{
char *end;
int n;
n = simple_strtoul(*str, &end, 0);
if ((*end != '\0') || (end == *str))
return -1;
*str = end;
*start_out = n;
*end_out = n;
return n;
}
int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
{
if (n >= num) {
*error_out = "Device number out of range";
return -EINVAL;
}
return setup_one_line(lines, n, "none", NULL, error_out);
}
int register_lines(struct line_driver *line_driver,
const struct tty_operations *ops,
struct line *lines, int nlines)
{
struct tty_driver *driver = alloc_tty_driver(nlines);
int err;
int i;
if (!driver)
return -ENOMEM;
driver->driver_name = line_driver->name;
driver->name = line_driver->device_name;
driver->major = line_driver->major;
driver->minor_start = line_driver->minor_start;
driver->type = line_driver->type;
driver->subtype = line_driver->subtype;
driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
driver->init_termios = tty_std_termios;
for (i = 0; i < nlines; i++) {
tty_port_init(&lines[i].port);
lines[i].port.ops = &line_port_ops;
spin_lock_init(&lines[i].lock);
lines[i].driver = line_driver;
INIT_LIST_HEAD(&lines[i].chan_list);
}
tty_set_operations(driver, ops);
err = tty_register_driver(driver);
if (err) {
printk(KERN_ERR "register_lines : can't register %s driver\n",
line_driver->name);
put_tty_driver(driver);
for (i = 0; i < nlines; i++)
tty_port_destroy(&lines[i].port);
return err;
}
line_driver->driver = driver;
mconsole_register_dev(&line_driver->mc);
return 0;
}
static DEFINE_SPINLOCK(winch_handler_lock);
static LIST_HEAD(winch_handlers);
struct winch {
struct list_head list;
int fd;
int tty_fd;
int pid;
struct tty_port *port;
unsigned long stack;
struct work_struct work;
};
static void __free_winch(struct work_struct *work)
{
struct winch *winch = container_of(work, struct winch, work);
um_free_irq(WINCH_IRQ, winch);
if (winch->pid != -1)
os_kill_process(winch->pid, 1);
if (winch->stack != 0)
free_stack(winch->stack, 0);
kfree(winch);
}
static void free_winch(struct winch *winch)
{
int fd = winch->fd;
winch->fd = -1;
if (fd != -1)
os_close_file(fd);
list_del(&winch->list);
__free_winch(&winch->work);
}
static irqreturn_t winch_interrupt(int irq, void *data)
{
struct winch *winch = data;
struct tty_struct *tty;
struct line *line;
int fd = winch->fd;
int err;
char c;
struct pid *pgrp;
if (fd != -1) {
err = generic_read(fd, &c, NULL);
if (err < 0) {
if (err != -EAGAIN) {
winch->fd = -1;
list_del(&winch->list);
os_close_file(fd);
printk(KERN_ERR "winch_interrupt : "
"read failed, errno = %d\n", -err);
printk(KERN_ERR "fd %d is losing SIGWINCH "
"support\n", winch->tty_fd);
INIT_WORK(&winch->work, __free_winch);
schedule_work(&winch->work);
return IRQ_HANDLED;
}
goto out;
}
}
tty = tty_port_tty_get(winch->port);
if (tty != NULL) {
line = tty->driver_data;
if (line != NULL) {
chan_window_size(line, &tty->winsize.ws_row,
&tty->winsize.ws_col);
pgrp = tty_get_pgrp(tty);
if (pgrp)
kill_pgrp(pgrp, SIGWINCH, 1);
put_pid(pgrp);
}
tty_kref_put(tty);
}
out:
if (winch->fd != -1)
reactivate_fd(winch->fd, WINCH_IRQ);
return IRQ_HANDLED;
}
void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
unsigned long stack)
{
struct winch *winch;
winch = kmalloc(sizeof(*winch), GFP_KERNEL);
if (winch == NULL) {
printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
goto cleanup;
}
*winch = ((struct winch) { .list = LIST_HEAD_INIT(winch->list),
.fd = fd,
.tty_fd = tty_fd,
.pid = pid,
.port = port,
.stack = stack });
if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
IRQF_SHARED, "winch", winch) < 0) {
printk(KERN_ERR "register_winch_irq - failed to register "
"IRQ\n");
goto out_free;
}
spin_lock(&winch_handler_lock);
list_add(&winch->list, &winch_handlers);
spin_unlock(&winch_handler_lock);
return;
out_free:
kfree(winch);
cleanup:
os_kill_process(pid, 1);
os_close_file(fd);
if (stack != 0)
free_stack(stack, 0);
}
static void unregister_winch(struct tty_struct *tty)
{
struct list_head *ele, *next;
struct winch *winch;
struct tty_struct *wtty;
spin_lock(&winch_handler_lock);
list_for_each_safe(ele, next, &winch_handlers) {
winch = list_entry(ele, struct winch, list);
wtty = tty_port_tty_get(winch->port);
if (wtty == tty) {
free_winch(winch);
break;
}
tty_kref_put(wtty);
}
spin_unlock(&winch_handler_lock);
}
static void winch_cleanup(void)
{
struct list_head *ele, *next;
struct winch *winch;
spin_lock(&winch_handler_lock);
list_for_each_safe(ele, next, &winch_handlers) {
winch = list_entry(ele, struct winch, list);
free_winch(winch);
}
spin_unlock(&winch_handler_lock);
}
__uml_exitcall(winch_cleanup);
char *add_xterm_umid(char *base)
{
char *umid, *title;
int len;
umid = get_umid();
if (*umid == '\0')
return base;
len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
title = kmalloc(len, GFP_KERNEL);
if (title == NULL) {
printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
return base;
}
snprintf(title, len, "%s (%s)", base, umid);
return title;
}