[PATCH 5.15 035/570] fbcon: Use delayed work for cursor

Greg Kroah-Hartman
2026-04-13T16:19:37Z

From: Daniel Vetter <daniel.vetter@ffwll.ch>

[ Upstream commit 3b0fb6ab25dda03f6077bf8fce9407bb0d4db6ea ]

Allows us to delete a bunch of hand-rolled stuff using a timer plus a
separate work). Also to simplify the code we initialize the
cursor_work completely when we allocate the fbcon_ops structure,
instead of trying to cope with console re-initialization.

The motiviation here is that fbcon code stops using the fb_info.queue,
which helps with locking issues around cleanup and all that in a later
patch.

Also note that this allows us to ditch the hand-rolled work cleanup in
fbcon_exit - we already call fbcon_del_cursor_timer, which takes care
of everything. Plus this was racy anyway.

v2:
- Only INIT_DELAYED_WORK when kzalloc succeeded (Tetsuo)
- Explain that we replace both the timer and a work with the combined
delayed_work (Javier)

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Claudio Suarez <cssk@net-c.es>
Cc: Du Cheng <ducheng2@gmail.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405210335.3434130-7-daniel.vetter@ffwll.ch
Stable-dep-of: 011a0502801c ("fbcon: check return value of con2fb_acquire_newinfo()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/video/fbdev/core/fbcon.c | 85 +++++++++++++-------------------
drivers/video/fbdev/core/fbcon.h | 4 +-
2 files changed, 35 insertions(+), 54 deletions(-)

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 8922595cc491d..4ad8618968715 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -342,8 +342,8 @@ static int get_color(struct vc_data *vc, struct fb_info *info,

static void fb_flashcursor(struct work_struct *work)
{
- struct fb_info *info = container_of(work, struct fb_info, queue);
- struct fbcon_ops *ops = info->fbcon_par;
+ struct fbcon_ops *ops = container_of(work, struct fbcon_ops, cursor_work.work);
+ struct fb_info *info;
struct vc_data *vc = NULL;
int c;
int mode;
@@ -356,7 +356,10 @@ static void fb_flashcursor(struct work_struct *work)
if (ret == 0)
return;

- if (ops && ops->currcon != -1)
+ /* protected by console_lock */
+ info = ops->info;
+
+ if (ops->currcon != -1)
vc = vc_cons[ops->currcon].d;

if (!vc || !con_is_visible(vc) ||
@@ -372,42 +375,25 @@ static void fb_flashcursor(struct work_struct *work)
ops->cursor(vc, info, mode, get_color(vc, info, c, 1),
get_color(vc, info, c, 0));
console_unlock();
-}

-static void cursor_timer_handler(struct timer_list *t)
-{
- struct fbcon_ops *ops = from_timer(ops, t, cursor_timer);
- struct fb_info *info = ops->info;
-
- queue_work(system_power_efficient_wq, &info->queue);
- mod_timer(&ops->cursor_timer, jiffies + ops->cur_blink_jiffies);
+ queue_delayed_work(system_power_efficient_wq, &ops->cursor_work,
+ ops->cur_blink_jiffies);
}

-static void fbcon_add_cursor_timer(struct fb_info *info)
+static void fbcon_add_cursor_work(struct fb_info *info)
{
struct fbcon_ops *ops = info->fbcon_par;

- if ((!info->queue.func || info->queue.func == fb_flashcursor) &&
- !(ops->flags & FBCON_FLAGS_CURSOR_TIMER) &&
- !fbcon_cursor_noblink) {
- if (!info->queue.func)
- INIT_WORK(&info->queue, fb_flashcursor);
-
- timer_setup(&ops->cursor_timer, cursor_timer_handler, 0);
- mod_timer(&ops->cursor_timer, jiffies + ops->cur_blink_jiffies);
- ops->flags |= FBCON_FLAGS_CURSOR_TIMER;
- }
+ if (!fbcon_cursor_noblink)
+ queue_delayed_work(system_power_efficient_wq, &ops->cursor_work,
+ ops->cur_blink_jiffies);
}

-static void fbcon_del_cursor_timer(struct fb_info *info)
+static void fbcon_del_cursor_work(struct fb_info *info)
{
struct fbcon_ops *ops = info->fbcon_par;

- if (info->queue.func == fb_flashcursor &&
- ops->flags & FBCON_FLAGS_CURSOR_TIMER) {
- del_timer_sync(&ops->cursor_timer);
- ops->flags &= ~FBCON_FLAGS_CURSOR_TIMER;
- }
+ cancel_delayed_work_sync(&ops->cursor_work);
}

#ifndef MODULE
@@ -711,6 +697,8 @@ static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
}

if (!err) {
+ INIT_DELAYED_WORK(&ops->cursor_work, fb_flashcursor);
+
ops->cur_blink_jiffies = HZ / 5;
ops->info = info;
info->fbcon_par = ops;
@@ -745,7 +733,7 @@ static int con2fb_release_oldinfo(struct vc_data *vc, struct fb_info *oldinfo,
}

if (!err) {
- fbcon_del_cursor_timer(oldinfo);
+ fbcon_del_cursor_work(oldinfo);
kfree(ops->cursor_state.mask);
kfree(ops->cursor_data);
kfree(ops->cursor_src);
@@ -862,7 +850,7 @@ static int set_con2fb_map(int unit, int newidx, int user)
logo_shown != FBCON_LOGO_DONTSHOW);

if (!found)
- fbcon_add_cursor_timer(info);
+ fbcon_add_cursor_work(info);
con2fb_map_boot[unit] = newidx;
con2fb_init_display(vc, info, unit, show_logo);
}
@@ -959,6 +947,8 @@ static const char *fbcon_startup(void)
return NULL;
}

+ INIT_DELAYED_WORK(&ops->cursor_work, fb_flashcursor);
+
ops->currcon = -1;
ops->graphics = 1;
ops->cur_rotate = -1;
@@ -999,7 +989,7 @@ static const char *fbcon_startup(void)
info->var.yres,
info->var.bits_per_pixel);

- fbcon_add_cursor_timer(info);
+ fbcon_add_cursor_work(info);
return display_desc;
}

@@ -1185,7 +1175,7 @@ static void fbcon_deinit(struct vc_data *vc)
goto finished;

if (con_is_visible(vc))
- fbcon_del_cursor_timer(info);
+ fbcon_del_cursor_work(info);

ops->flags &= ~FBCON_FLAGS_INIT;
finished:
@@ -1318,9 +1308,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
return;

if (vc->vc_cursor_type & CUR_SW)
- fbcon_del_cursor_timer(info);
+ fbcon_del_cursor_work(info);
else
- fbcon_add_cursor_timer(info);
+ fbcon_add_cursor_work(info);

ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;

@@ -2126,14 +2116,14 @@ static bool fbcon_switch(struct vc_data *vc)
}

if (old_info != info)
- fbcon_del_cursor_timer(old_info);
+ fbcon_del_cursor_work(old_info);
}

if (fbcon_is_inactive(vc, info) ||
ops->blank_state != FB_BLANK_UNBLANK)
- fbcon_del_cursor_timer(info);
+ fbcon_del_cursor_work(info);
else
- fbcon_add_cursor_timer(info);
+ fbcon_add_cursor_work(info);

set_blitting_type(vc, info);
ops->cursor_reset = 1;
@@ -2241,9 +2231,9 @@ static int fbcon_blank(struct vc_data *vc, int blank, int mode_switch)

if (mode_switch || fbcon_is_inactive(vc, info) ||
ops->blank_state != FB_BLANK_UNBLANK)
- fbcon_del_cursor_timer(info);
+ fbcon_del_cursor_work(info);
else
- fbcon_add_cursor_timer(info);
+ fbcon_add_cursor_work(info);

return 0;
}
@@ -3240,7 +3230,7 @@ static ssize_t show_cursor_blink(struct device *device,
if (!ops)
goto err;

- blink = (ops->flags & FBCON_FLAGS_CURSOR_TIMER) ? 1 : 0;
+ blink = delayed_work_pending(&ops->cursor_work);
err:
console_unlock();
return snprintf(buf, PAGE_SIZE, "%d\n", blink);
@@ -3269,10 +3259,10 @@ static ssize_t store_cursor_blink(struct device *device,

if (blink) {
fbcon_cursor_noblink = 0;
- fbcon_add_cursor_timer(info);
+ fbcon_add_cursor_work(info);
} else {
fbcon_cursor_noblink = 1;
- fbcon_del_cursor_timer(info);
+ fbcon_del_cursor_work(info);
}

err:
@@ -3385,15 +3375,9 @@ static void fbcon_exit(void)
#endif

for_each_registered_fb(i) {
- int pending = 0;
-
mapped = 0;
info = registered_fb[i];

- if (info->queue.func)
- pending = cancel_work_sync(&info->queue);
- pr_debug("fbcon: %s pending work\n", (pending ? "canceled" : "no"));
-
for (j = first_fb_vc; j <= last_fb_vc; j++) {
if (con2fb_map[j] == i) {
mapped = 1;
@@ -3409,15 +3393,12 @@ static void fbcon_exit(void)
if (info->fbcon_par) {
struct fbcon_ops *ops = info->fbcon_par;

- fbcon_del_cursor_timer(info);
+ fbcon_del_cursor_work(info);
kfree(ops->cursor_src);
kfree(ops->cursor_state.mask);
kfree(info->fbcon_par);
info->fbcon_par = NULL;
}
-
- if (info->queue.func == fb_flashcursor)
- info->queue.func = NULL;
}
}
}
diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
index 3e1ec454b8aa3..a709e5796ef7e 100644
--- a/drivers/video/fbdev/core/fbcon.h
+++ b/drivers/video/fbdev/core/fbcon.h
@@ -14,11 +14,11 @@
#include <linux/types.h>
#include <linux/vt_buffer.h>
#include <linux/vt_kern.h>
+#include <linux/workqueue.h>

#include <asm/io.h>

#define FBCON_FLAGS_INIT 1
-#define FBCON_FLAGS_CURSOR_TIMER 2

/*
* This is the interface between the low-level console driver and the
@@ -68,7 +68,7 @@ struct fbcon_ops {
int (*update_start)(struct fb_info *info);
int (*rotate_font)(struct fb_info *info, struct vc_data *vc);
struct fb_var_screeninfo var; /* copy of the current fb_var_screeninfo */
- struct timer_list cursor_timer; /* Cursor timer */
+ struct delayed_work cursor_work; /* Cursor timer */
struct fb_cursor cursor_state;
struct fbcon_display *p;
struct fb_info *info;
--
2.51.0