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HID: picolcd: implement refcounting of framebuffer

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As our device may be hot-unplugged and framebuffer cannot handle
this case by itself we need to keep track of usage count so as
to release fb_info and framebuffer memory only after the last user
has closed framebuffer.

We need to do the freeing in a scheduled work as fb_release()
is called with fb_info lock held.

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Bruno Prémont 2010-06-28 22:33:27 +02:00 committed by Jiri Kosina
parent 365f1fcd0d
commit 225b459006
1 changed files with 103 additions and 7 deletions
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110
drivers/hid/hid-picolcd.c
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@ -439,6 +439,9 @@ static void picolcd_fb_update(struct picolcd_data *data)
int chip, tile, n;
unsigned long flags;
if (!data)
return;
spin_lock_irqsave(&data->lock, flags);
if (!(data->status & PICOLCD_READY_FB)) {
spin_unlock_irqrestore(&data->lock, flags);
@ -461,6 +464,8 @@ static void picolcd_fb_update(struct picolcd_data *data)
data->fb_bitmap, data->fb_bpp, chip, tile) ||
data->fb_force) {
n += 2;
if (!data->fb_info->par)
return; /* device lost! */
if (n >= HID_OUTPUT_FIFO_SIZE / 2) {
usbhid_wait_io(data->hdev);
n = 0;
@ -531,11 +536,23 @@ static int picolcd_fb_blank(int blank, struct fb_info *info)
static void picolcd_fb_destroy(struct fb_info *info)
{
struct picolcd_data *data = info->par;
u32 *ref_cnt = info->pseudo_palette;
int may_release;
info->par = NULL;
if (data)
data->fb_info = NULL;
fb_deferred_io_cleanup(info);
framebuffer_release(info);
ref_cnt--;
mutex_lock(&info->lock);
(*ref_cnt)--;
may_release = !ref_cnt;
mutex_unlock(&info->lock);
if (may_release) {
framebuffer_release(info);
vfree((u8 *)info->fix.smem_start);
}
}
static int picolcd_fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
@ -564,6 +581,8 @@ static int picolcd_set_par(struct fb_info *info)
{
struct picolcd_data *data = info->par;
u8 *tmp_fb, *o_fb;
if (!data)
return -ENODEV;
if (info->var.bits_per_pixel == data->fb_bpp)
return 0;
/* switch between 1/8 bit depths */
@ -603,10 +622,77 @@ static int picolcd_set_par(struct fb_info *info)
return 0;
}
/* Do refcounting on our FB and cleanup per worker if FB is
* closed after unplug of our device
* (fb_release holds info->lock and still touches info after
* we return so we can't release it immediately.
*/
struct picolcd_fb_cleanup_item {
struct fb_info *info;
struct picolcd_fb_cleanup_item *next;
};
static struct picolcd_fb_cleanup_item *fb_pending;
DEFINE_SPINLOCK(fb_pending_lock);
static void picolcd_fb_do_cleanup(struct work_struct *data)
{
struct picolcd_fb_cleanup_item *item;
unsigned long flags;
do {
spin_lock_irqsave(&fb_pending_lock, flags);
item = fb_pending;
fb_pending = item ? item->next : NULL;
spin_unlock_irqrestore(&fb_pending_lock, flags);
if (item) {
u8 *fb = (u8 *)item->info->fix.smem_start;
/* make sure we do not race against fb core when
* releasing */
mutex_lock(&item->info->lock);
mutex_unlock(&item->info->lock);
framebuffer_release(item->info);
vfree(fb);
}
} while (item);
}
DECLARE_WORK(picolcd_fb_cleanup, picolcd_fb_do_cleanup);
static int picolcd_fb_open(struct fb_info *info, int u)
{
u32 *ref_cnt = info->pseudo_palette;
ref_cnt--;
(*ref_cnt)++;
return 0;
}
static int picolcd_fb_release(struct fb_info *info, int u)
{
u32 *ref_cnt = info->pseudo_palette;
ref_cnt--;
(*ref_cnt)++;
if (!*ref_cnt) {
unsigned long flags;
struct picolcd_fb_cleanup_item *item = (struct picolcd_fb_cleanup_item *)ref_cnt;
item--;
spin_lock_irqsave(&fb_pending_lock, flags);
item->next = fb_pending;
fb_pending = item;
spin_unlock_irqrestore(&fb_pending_lock, flags);
schedule_work(&picolcd_fb_cleanup);
}
return 0;
}
/* Note this can't be const because of struct fb_info definition */
static struct fb_ops picolcdfb_ops = {
.owner = THIS_MODULE,
.fb_destroy = picolcd_fb_destroy,
.fb_open = picolcd_fb_open,
.fb_release = picolcd_fb_release,
.fb_read = fb_sys_read,
.fb_write = picolcd_fb_write,
.fb_blank = picolcd_fb_blank,
@ -708,13 +794,13 @@ static int picolcd_init_framebuffer(struct picolcd_data *data)
* - u32 for ref_count
* - 256*u32 for pseudo_palette
*/
info = framebuffer_alloc(257 * sizeof(u32), dev);
info = framebuffer_alloc(257 * sizeof(u32) + sizeof(struct picolcd_fb_cleanup_item), dev);
if (info == NULL) {
dev_err(dev, "failed to allocate a framebuffer\n");
goto err_nomem;
}
palette = info->par;
palette = info->par + sizeof(struct picolcd_fb_cleanup_item);
*palette = 1;
palette++;
for (i = 0; i < 256; i++)
@ -775,18 +861,17 @@ static void picolcd_exit_framebuffer(struct picolcd_data *data)
{
struct fb_info *info = data->fb_info;
u8 *fb_vbitmap = data->fb_vbitmap;
u8 *fb_bitmap = data->fb_bitmap;
if (!info)
return;
info->par = NULL;
device_remove_file(&data->hdev->dev, &dev_attr_fb_update_rate);
unregister_framebuffer(info);
data->fb_vbitmap = NULL;
data->fb_bitmap = NULL;
data->fb_bpp = 0;
data->fb_info = NULL;
device_remove_file(&data->hdev->dev, &dev_attr_fb_update_rate);
unregister_framebuffer(info);
vfree(fb_bitmap);
kfree(fb_vbitmap);
}
@ -2603,6 +2688,13 @@ static void picolcd_remove(struct hid_device *hdev)
spin_lock_irqsave(&data->lock, flags);
data->status |= PICOLCD_FAILED;
spin_unlock_irqrestore(&data->lock, flags);
#ifdef CONFIG_HID_PICOLCD_FB
/* short-circuit FB as early as possible in order to
* avoid long delays if we host console.
*/
if (data->fb_info)
data->fb_info->par = NULL;
#endif
picolcd_exit_devfs(data);
device_remove_file(&hdev->dev, &dev_attr_operation_mode);
@ -2660,6 +2752,10 @@ static int __init picolcd_init(void)
static void __exit picolcd_exit(void)
{
hid_unregister_driver(&picolcd_driver);
#ifdef CONFIG_HID_PICOLCD_FB
flush_scheduled_work();
WARN_ON(fb_pending);
#endif
}
module_init(picolcd_init);