[PATCH 16/21] fbcon: Move console_lock for register/unlink/unregister

Daniel Vetter
2022-01-31T21:08:28Z

Ideally console_lock becomes an implementation detail of fbcon.c and
doesn't show up anywhere in fbmem.c. We're still pretty far from that,
but at least the register/unregister code is there now.

With this the do_fb_ioctl() handler is the only code in fbmem.c still
calling console_lock().

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Du Cheng <ducheng2@gmail.com>
Cc: Claudio Suarez <cssk@net-c.es>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Zheyu Ma <zheyuma97@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn>
---
drivers/video/fbdev/core/fbcon.c | 33 ++++++++++++++++++++++++++------
drivers/video/fbdev/core/fbmem.c | 23 ++--------------------
2 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 11b9f962af6f..e5e8aaf6f60d 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -2776,10 +2776,12 @@ void fbcon_fb_unbind(struct fb_info *info)
int i, new_idx = -1;
int idx = info->node;

- WARN_CONSOLE_UNLOCKED();
+ console_lock();

- if (!fbcon_has_console_bind)
+ if (!fbcon_has_console_bind) {
+ console_unlock();
return;
+ }

for (i = first_fb_vc; i <= last_fb_vc; i++) {
if (con2fb_map[i] != idx &&
@@ -2814,6 +2816,8 @@ void fbcon_fb_unbind(struct fb_info *info)
}
fbcon_unbind();
}
+
+ console_unlock();
}

/* called with console_lock held */
@@ -2821,10 +2825,12 @@ void fbcon_fb_unregistered(struct fb_info *info)
{
int i, idx;

- WARN_CONSOLE_UNLOCKED();
+ console_lock();

- if (deferred_takeover)
+ if (deferred_takeover) {
+ console_unlock();
return;
+ }

idx = info->node;
for (i = first_fb_vc; i <= last_fb_vc; i++) {
@@ -2853,6 +2859,7 @@ void fbcon_fb_unregistered(struct fb_info *info)

if (!num_registered_fb)
do_unregister_con_driver(&fb_con);
+ console_unlock();
}

void fbcon_remap_all(struct fb_info *info)
@@ -2910,19 +2917,27 @@ static inline void fbcon_select_primary(struct fb_info *info)
}
#endif /* CONFIG_FRAMEBUFFER_DETECT_PRIMARY */

+static bool lockless_register_fb;
+module_param_named_unsafe(lockless_register_fb, lockless_register_fb, bool, 0400);
+MODULE_PARM_DESC(lockless_register_fb,
+ "Lockless framebuffer registration for debugging [default=off]");
+
/* called with console_lock held */
int fbcon_fb_registered(struct fb_info *info)
{
int ret = 0, i, idx;

- WARN_CONSOLE_UNLOCKED();
+ if (!lockless_register_fb)
+ console_lock();
+ else
+ atomic_inc(&ignore_console_lock_warning);

idx = info->node;
fbcon_select_primary(info);

if (deferred_takeover) {
pr_info("fbcon: Deferring console take-over\n");
- return 0;
+ goto out;
}

if (info_idx == -1) {
@@ -2942,6 +2957,12 @@ int fbcon_fb_registered(struct fb_info *info)
}
}

+out:
+ if (!lockless_register_fb)
+ console_unlock();
+ else
+ atomic_dec(&ignore_console_lock_warning);
+
return ret;
}

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index fd51d12f2702..904ef1250677 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1573,14 +1573,9 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
}
}

-static bool lockless_register_fb;
-module_param_named_unsafe(lockless_register_fb, lockless_register_fb, bool, 0400);
-MODULE_PARM_DESC(lockless_register_fb,
- "Lockless framebuffer registration for debugging [default=off]");
-
static int do_register_framebuffer(struct fb_info *fb_info)
{
- int i, ret;
+ int i;
struct fb_videomode mode;

if (fb_check_foreignness(fb_info))
@@ -1649,17 +1644,7 @@ static int do_register_framebuffer(struct fb_info *fb_info)
}
#endif

- if (!lockless_register_fb)
- console_lock();
- else
- atomic_inc(&ignore_console_lock_warning);
- ret = fbcon_fb_registered(fb_info);
-
- if (!lockless_register_fb)
- console_unlock();
- else
- atomic_dec(&ignore_console_lock_warning);
- return ret;
+ return fbcon_fb_registered(fb_info);
}

static void unbind_console(struct fb_info *fb_info)
@@ -1669,9 +1654,7 @@ static void unbind_console(struct fb_info *fb_info)
if (WARN_ON(i < 0 || i >= FB_MAX || registered_fb[i] != fb_info))
return;

- console_lock();
fbcon_fb_unbind(fb_info);
- console_unlock();
}

static void unlink_framebuffer(struct fb_info *fb_info)
@@ -1714,9 +1697,7 @@ static void do_unregister_framebuffer(struct fb_info *fb_info)
fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
}
#endif
- console_lock();
fbcon_fb_unregistered(fb_info);
- console_unlock();

/* this may free fb info */
put_fb_info(fb_info);
--
2.33.0