fbcon: Use delayed work for cursor

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

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 83f0223..7592996 100644 (file)
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -350,8 +350,8 @@ 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;
@@ -364,7 +364,10 @@ 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) ||
@@ -380,42 +383,25 @@ 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
@@ -717,6 +703,8 @@ 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;
@@ -751,7 +739,7 @@ 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);
@@ -867,7 +855,7 @@ 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);
        }
@@ -964,6 +952,8 @@ 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;
@@ -1006,7 +996,7 @@ 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;
 }
 
@@ -1194,7 +1184,7 @@ 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:
@@ -1320,9 +1310,9 @@ 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;
 
@@ -2132,14 +2122,14 @@ static int 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;
@@ -2247,9 +2237,9 @@ 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;
 }
@@ -3181,7 +3171,7 @@ 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);
@@ -3210,10 +3200,10 @@ 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:
@@ -3314,15 +3304,9 @@ 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;
@@ -3338,15 +3322,12 @@ 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 969d41e..6708ca0 100644 (file)
--- 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;