kernel-fxtec-pro1x/drivers/video/fbsysfs.c
Gu Zheng 3a41c5dbe8 fb: reorder the lock sequence to fix potential dead lock
Following commits:

50e244cc79 fb: rework locking to fix lock ordering on takeover
e93a9a8687 fb: Yet another band-aid for fixing lockdep mess
054430e773 fbcon: fix locking harder

reworked locking to fix related lock ordering on takeover, and introduced console_lock
into fbmem, but it seems that the new lock sequence(fb_info->lock ---> console_lock)
is against with the one in console_callback(console_lock ---> fb_info->lock), and leads to
a potential dead lock as following:

[  601.079000] ======================================================
[  601.079000] [ INFO: possible circular locking dependency detected ]
[  601.079000] 3.11.0  Not tainted
[  601.079000] -------------------------------------------------------
[  601.079000] kworker/0:3/619 is trying to acquire lock:
[  601.079000]  (&fb_info->lock){+.+.+.}, at: [<ffffffff81397566>] lock_fb_info+0x26/0x60
[  601.079000]
but task is already holding lock:
[  601.079000]  (console_lock){+.+.+.}, at: [<ffffffff8141aae3>] console_callback+0x13/0x160
[  601.079000]
which lock already depends on the new lock.

[  601.079000]
the existing dependency chain (in reverse order) is:
[  601.079000]
->  (console_lock){+.+.+.}:
[  601.079000]        [<ffffffff810dc971>] lock_acquire+0xa1/0x140
[  601.079000]        [<ffffffff810c6267>] console_lock+0x77/0x80
[  601.079000]        [<ffffffff81399448>] register_framebuffer+0x1d8/0x320
[  601.079000]        [<ffffffff81cfb4c8>] efifb_probe+0x408/0x48f
[  601.079000]        [<ffffffff8144a963>] platform_drv_probe+0x43/0x80
[  601.079000]        [<ffffffff8144853b>] driver_probe_device+0x8b/0x390
[  601.079000]        [<ffffffff814488eb>] __driver_attach+0xab/0xb0
[  601.079000]        [<ffffffff814463bd>] bus_for_each_dev+0x5d/0xa0
[  601.079000]        [<ffffffff81447e6e>] driver_attach+0x1e/0x20
[  601.079000]        [<ffffffff81447a07>] bus_add_driver+0x117/0x290
[  601.079000]        [<ffffffff81448fea>] driver_register+0x7a/0x170
[  601.079000]        [<ffffffff8144a10a>] __platform_driver_register+0x4a/0x50
[  601.079000]        [<ffffffff8144a12d>] platform_driver_probe+0x1d/0xb0
[  601.079000]        [<ffffffff81cfb0a1>] efifb_init+0x273/0x292
[  601.079000]        [<ffffffff81002132>] do_one_initcall+0x102/0x1c0
[  601.079000]        [<ffffffff81cb80a6>] kernel_init_freeable+0x15d/0x1ef
[  601.079000]        [<ffffffff8166d2de>] kernel_init+0xe/0xf0
[  601.079000]        [<ffffffff816914ec>] ret_from_fork+0x7c/0xb0
[  601.079000]
->  (&fb_info->lock){+.+.+.}:
[  601.079000]        [<ffffffff810dc1d8>] __lock_acquire+0x1e18/0x1f10
[  601.079000]        [<ffffffff810dc971>] lock_acquire+0xa1/0x140
[  601.079000]        [<ffffffff816835ca>] mutex_lock_nested+0x7a/0x3b0
[  601.079000]        [<ffffffff81397566>] lock_fb_info+0x26/0x60
[  601.079000]        [<ffffffff813a4aeb>] fbcon_blank+0x29b/0x2e0
[  601.079000]        [<ffffffff81418658>] do_blank_screen+0x1d8/0x280
[  601.079000]        [<ffffffff8141ab34>] console_callback+0x64/0x160
[  601.079000]        [<ffffffff8108d855>] process_one_work+0x1f5/0x540
[  601.079000]        [<ffffffff8108e04c>] worker_thread+0x11c/0x370
[  601.079000]        [<ffffffff81095fbd>] kthread+0xed/0x100
[  601.079000]        [<ffffffff816914ec>] ret_from_fork+0x7c/0xb0
[  601.079000]
other info that might help us debug this:

[  601.079000]  Possible unsafe locking scenario:

[  601.079000]        CPU0                    CPU1
[  601.079000]        ----                    ----
[  601.079000]   lock(console_lock);
[  601.079000]                                lock(&fb_info->lock);
[  601.079000]                                lock(console_lock);
[  601.079000]   lock(&fb_info->lock);
[  601.079000]
 *** DEADLOCK ***

so we reorder the lock sequence the same as it in console_callback() to
avoid this issue. And following Tomi's suggestion, fix these similar
issues all in fb subsystem.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
2013-11-11 15:52:59 +02:00

586 lines
14 KiB
C

/*
* fbsysfs.c - framebuffer device class and attributes
*
* Copyright (c) 2004 James Simmons <jsimmons@infradead.org>
*
* This program is free software you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
/*
* Note: currently there's only stubs for framebuffer_alloc and
* framebuffer_release here. The reson for that is that until all drivers
* are converted to use it a sysfsification will open OOPSable races.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/console.h>
#include <linux/module.h>
#define FB_SYSFS_FLAG_ATTR 1
/**
* framebuffer_alloc - creates a new frame buffer info structure
*
* @size: size of driver private data, can be zero
* @dev: pointer to the device for this fb, this can be NULL
*
* Creates a new frame buffer info structure. Also reserves @size bytes
* for driver private data (info->par). info->par (if any) will be
* aligned to sizeof(long).
*
* Returns the new structure, or NULL if an error occurred.
*
*/
struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
{
#define BYTES_PER_LONG (BITS_PER_LONG/8)
#define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))
int fb_info_size = sizeof(struct fb_info);
struct fb_info *info;
char *p;
if (size)
fb_info_size += PADDING;
p = kzalloc(fb_info_size + size, GFP_KERNEL);
if (!p)
return NULL;
info = (struct fb_info *) p;
if (size)
info->par = p + fb_info_size;
info->device = dev;
#ifdef CONFIG_FB_BACKLIGHT
mutex_init(&info->bl_curve_mutex);
#endif
return info;
#undef PADDING
#undef BYTES_PER_LONG
}
EXPORT_SYMBOL(framebuffer_alloc);
/**
* framebuffer_release - marks the structure available for freeing
*
* @info: frame buffer info structure
*
* Drop the reference count of the device embedded in the
* framebuffer info structure.
*
*/
void framebuffer_release(struct fb_info *info)
{
if (!info)
return;
kfree(info->apertures);
kfree(info);
}
EXPORT_SYMBOL(framebuffer_release);
static int activate(struct fb_info *fb_info, struct fb_var_screeninfo *var)
{
int err;
var->activate |= FB_ACTIVATE_FORCE;
console_lock();
fb_info->flags |= FBINFO_MISC_USEREVENT;
err = fb_set_var(fb_info, var);
fb_info->flags &= ~FBINFO_MISC_USEREVENT;
console_unlock();
if (err)
return err;
return 0;
}
static int mode_string(char *buf, unsigned int offset,
const struct fb_videomode *mode)
{
char m = 'U';
char v = 'p';
if (mode->flag & FB_MODE_IS_DETAILED)
m = 'D';
if (mode->flag & FB_MODE_IS_VESA)
m = 'V';
if (mode->flag & FB_MODE_IS_STANDARD)
m = 'S';
if (mode->vmode & FB_VMODE_INTERLACED)
v = 'i';
if (mode->vmode & FB_VMODE_DOUBLE)
v = 'd';
return snprintf(&buf[offset], PAGE_SIZE - offset, "%c:%dx%d%c-%d\n",
m, mode->xres, mode->yres, v, mode->refresh);
}
static ssize_t store_mode(struct device *device, struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
char mstr[100];
struct fb_var_screeninfo var;
struct fb_modelist *modelist;
struct fb_videomode *mode;
struct list_head *pos;
size_t i;
int err;
memset(&var, 0, sizeof(var));
list_for_each(pos, &fb_info->modelist) {
modelist = list_entry(pos, struct fb_modelist, list);
mode = &modelist->mode;
i = mode_string(mstr, 0, mode);
if (strncmp(mstr, buf, max(count, i)) == 0) {
var = fb_info->var;
fb_videomode_to_var(&var, mode);
if ((err = activate(fb_info, &var)))
return err;
fb_info->mode = mode;
return count;
}
}
return -EINVAL;
}
static ssize_t show_mode(struct device *device, struct device_attribute *attr,
char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
if (!fb_info->mode)
return 0;
return mode_string(buf, 0, fb_info->mode);
}
static ssize_t store_modes(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
LIST_HEAD(old_list);
int i = count / sizeof(struct fb_videomode);
if (i * sizeof(struct fb_videomode) != count)
return -EINVAL;
console_lock();
if (!lock_fb_info(fb_info)) {
console_unlock();
return -ENODEV;
}
list_splice(&fb_info->modelist, &old_list);
fb_videomode_to_modelist((const struct fb_videomode *)buf, i,
&fb_info->modelist);
if (fb_new_modelist(fb_info)) {
fb_destroy_modelist(&fb_info->modelist);
list_splice(&old_list, &fb_info->modelist);
} else
fb_destroy_modelist(&old_list);
unlock_fb_info(fb_info);
console_unlock();
return 0;
}
static ssize_t show_modes(struct device *device, struct device_attribute *attr,
char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
unsigned int i;
struct list_head *pos;
struct fb_modelist *modelist;
const struct fb_videomode *mode;
i = 0;
list_for_each(pos, &fb_info->modelist) {
modelist = list_entry(pos, struct fb_modelist, list);
mode = &modelist->mode;
i += mode_string(buf, i, mode);
}
return i;
}
static ssize_t store_bpp(struct device *device, struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
struct fb_var_screeninfo var;
char ** last = NULL;
int err;
var = fb_info->var;
var.bits_per_pixel = simple_strtoul(buf, last, 0);
if ((err = activate(fb_info, &var)))
return err;
return count;
}
static ssize_t show_bpp(struct device *device, struct device_attribute *attr,
char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%d\n", fb_info->var.bits_per_pixel);
}
static ssize_t store_rotate(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
struct fb_var_screeninfo var;
char **last = NULL;
int err;
var = fb_info->var;
var.rotate = simple_strtoul(buf, last, 0);
if ((err = activate(fb_info, &var)))
return err;
return count;
}
static ssize_t show_rotate(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%d\n", fb_info->var.rotate);
}
static ssize_t store_virtual(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
struct fb_var_screeninfo var;
char *last = NULL;
int err;
var = fb_info->var;
var.xres_virtual = simple_strtoul(buf, &last, 0);
last++;
if (last - buf >= count)
return -EINVAL;
var.yres_virtual = simple_strtoul(last, &last, 0);
if ((err = activate(fb_info, &var)))
return err;
return count;
}
static ssize_t show_virtual(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%d,%d\n", fb_info->var.xres_virtual,
fb_info->var.yres_virtual);
}
static ssize_t show_stride(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%d\n", fb_info->fix.line_length);
}
static ssize_t store_blank(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
char *last = NULL;
int err;
console_lock();
fb_info->flags |= FBINFO_MISC_USEREVENT;
err = fb_blank(fb_info, simple_strtoul(buf, &last, 0));
fb_info->flags &= ~FBINFO_MISC_USEREVENT;
console_unlock();
if (err < 0)
return err;
return count;
}
static ssize_t show_blank(struct device *device,
struct device_attribute *attr, char *buf)
{
// struct fb_info *fb_info = dev_get_drvdata(device);
return 0;
}
static ssize_t store_console(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
// struct fb_info *fb_info = dev_get_drvdata(device);
return 0;
}
static ssize_t show_console(struct device *device,
struct device_attribute *attr, char *buf)
{
// struct fb_info *fb_info = dev_get_drvdata(device);
return 0;
}
static ssize_t store_cursor(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
// struct fb_info *fb_info = dev_get_drvdata(device);
return 0;
}
static ssize_t show_cursor(struct device *device,
struct device_attribute *attr, char *buf)
{
// struct fb_info *fb_info = dev_get_drvdata(device);
return 0;
}
static ssize_t store_pan(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
struct fb_var_screeninfo var;
char *last = NULL;
int err;
var = fb_info->var;
var.xoffset = simple_strtoul(buf, &last, 0);
last++;
if (last - buf >= count)
return -EINVAL;
var.yoffset = simple_strtoul(last, &last, 0);
console_lock();
err = fb_pan_display(fb_info, &var);
console_unlock();
if (err < 0)
return err;
return count;
}
static ssize_t show_pan(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%d,%d\n", fb_info->var.xoffset,
fb_info->var.yoffset);
}
static ssize_t show_name(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%s\n", fb_info->fix.id);
}
static ssize_t store_fbstate(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
u32 state;
char *last = NULL;
state = simple_strtoul(buf, &last, 0);
console_lock();
if (!lock_fb_info(fb_info)) {
console_unlock();
return -ENODEV;
}
fb_set_suspend(fb_info, (int)state);
unlock_fb_info(fb_info);
console_unlock();
return count;
}
static ssize_t show_fbstate(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
return snprintf(buf, PAGE_SIZE, "%d\n", fb_info->state);
}
#ifdef CONFIG_FB_BACKLIGHT
static ssize_t store_bl_curve(struct device *device,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fb_info *fb_info = dev_get_drvdata(device);
u8 tmp_curve[FB_BACKLIGHT_LEVELS];
unsigned int i;
/* Some drivers don't use framebuffer_alloc(), but those also
* don't have backlights.
*/
if (!fb_info || !fb_info->bl_dev)
return -ENODEV;
if (count != (FB_BACKLIGHT_LEVELS / 8 * 24))
return -EINVAL;
for (i = 0; i < (FB_BACKLIGHT_LEVELS / 8); ++i)
if (sscanf(&buf[i * 24],
"%2hhx %2hhx %2hhx %2hhx %2hhx %2hhx %2hhx %2hhx\n",
&tmp_curve[i * 8 + 0],
&tmp_curve[i * 8 + 1],
&tmp_curve[i * 8 + 2],
&tmp_curve[i * 8 + 3],
&tmp_curve[i * 8 + 4],
&tmp_curve[i * 8 + 5],
&tmp_curve[i * 8 + 6],
&tmp_curve[i * 8 + 7]) != 8)
return -EINVAL;
/* If there has been an error in the input data, we won't
* reach this loop.
*/
mutex_lock(&fb_info->bl_curve_mutex);
for (i = 0; i < FB_BACKLIGHT_LEVELS; ++i)
fb_info->bl_curve[i] = tmp_curve[i];
mutex_unlock(&fb_info->bl_curve_mutex);
return count;
}
static ssize_t show_bl_curve(struct device *device,
struct device_attribute *attr, char *buf)
{
struct fb_info *fb_info = dev_get_drvdata(device);
ssize_t len = 0;
unsigned int i;
/* Some drivers don't use framebuffer_alloc(), but those also
* don't have backlights.
*/
if (!fb_info || !fb_info->bl_dev)
return -ENODEV;
mutex_lock(&fb_info->bl_curve_mutex);
for (i = 0; i < FB_BACKLIGHT_LEVELS; i += 8)
len += snprintf(&buf[len], PAGE_SIZE,
"%02x %02x %02x %02x %02x %02x %02x %02x\n",
fb_info->bl_curve[i + 0],
fb_info->bl_curve[i + 1],
fb_info->bl_curve[i + 2],
fb_info->bl_curve[i + 3],
fb_info->bl_curve[i + 4],
fb_info->bl_curve[i + 5],
fb_info->bl_curve[i + 6],
fb_info->bl_curve[i + 7]);
mutex_unlock(&fb_info->bl_curve_mutex);
return len;
}
#endif
/* When cmap is added back in it should be a binary attribute
* not a text one. Consideration should also be given to converting
* fbdev to use configfs instead of sysfs */
static struct device_attribute device_attrs[] = {
__ATTR(bits_per_pixel, S_IRUGO|S_IWUSR, show_bpp, store_bpp),
__ATTR(blank, S_IRUGO|S_IWUSR, show_blank, store_blank),
__ATTR(console, S_IRUGO|S_IWUSR, show_console, store_console),
__ATTR(cursor, S_IRUGO|S_IWUSR, show_cursor, store_cursor),
__ATTR(mode, S_IRUGO|S_IWUSR, show_mode, store_mode),
__ATTR(modes, S_IRUGO|S_IWUSR, show_modes, store_modes),
__ATTR(pan, S_IRUGO|S_IWUSR, show_pan, store_pan),
__ATTR(virtual_size, S_IRUGO|S_IWUSR, show_virtual, store_virtual),
__ATTR(name, S_IRUGO, show_name, NULL),
__ATTR(stride, S_IRUGO, show_stride, NULL),
__ATTR(rotate, S_IRUGO|S_IWUSR, show_rotate, store_rotate),
__ATTR(state, S_IRUGO|S_IWUSR, show_fbstate, store_fbstate),
#ifdef CONFIG_FB_BACKLIGHT
__ATTR(bl_curve, S_IRUGO|S_IWUSR, show_bl_curve, store_bl_curve),
#endif
};
int fb_init_device(struct fb_info *fb_info)
{
int i, error = 0;
dev_set_drvdata(fb_info->dev, fb_info);
fb_info->class_flag |= FB_SYSFS_FLAG_ATTR;
for (i = 0; i < ARRAY_SIZE(device_attrs); i++) {
error = device_create_file(fb_info->dev, &device_attrs[i]);
if (error)
break;
}
if (error) {
while (--i >= 0)
device_remove_file(fb_info->dev, &device_attrs[i]);
fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;
}
return 0;
}
void fb_cleanup_device(struct fb_info *fb_info)
{
unsigned int i;
if (fb_info->class_flag & FB_SYSFS_FLAG_ATTR) {
for (i = 0; i < ARRAY_SIZE(device_attrs); i++)
device_remove_file(fb_info->dev, &device_attrs[i]);
fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;
}
}
#ifdef CONFIG_FB_BACKLIGHT
/* This function generates a linear backlight curve
*
* 0: off
* 1-7: min
* 8-127: linear from min to max
*/
void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max)
{
unsigned int i, flat, count, range = (max - min);
mutex_lock(&fb_info->bl_curve_mutex);
fb_info->bl_curve[0] = off;
for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat)
fb_info->bl_curve[flat] = min;
count = FB_BACKLIGHT_LEVELS * 15 / 16;
for (i = 0; i < count; ++i)
fb_info->bl_curve[flat + i] = min + (range * (i + 1) / count);
mutex_unlock(&fb_info->bl_curve_mutex);
}
EXPORT_SYMBOL_GPL(fb_bl_default_curve);
#endif