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From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: LKML <linux-kernel@vger.kernel.org>
Cc: "Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Bartlomiej Zolnierkiewicz" <b.zolnierkie@samsung.com>,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Noralf Trønnes" <noralf@tronnes.org>,
	"Yisheng Xie" <ysxie@foxmail.com>,
	"Konstantin Khorenko" <khorenko@virtuozzo.com>,
	"Prarit Bhargava" <prarit@redhat.com>,
	"Kees Cook" <keescook@chromium.org>
Subject: [PATCH 09/33] fbcon: Remove fbcon_has_exited
Date: Fri, 24 May 2019 10:53:30 +0200	[thread overview]
Message-ID: <20190524085354.27411-10-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20190524085354.27411-1-daniel.vetter@ffwll.ch>

This is unused code since

commit 6104c37094e729f3d4ce65797002112735d49cd1
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Aug 1 17:32:07 2017 +0200

    fbcon: Make fbcon a built-time depency for fbdev

when fbcon was made a compile-time static dependency of fbdev. We
can't exit fbcon anymore without exiting fbdev first, which only works
if all fbdev drivers have unloaded already. Hence this is all dead
code.

v2: I missed that fbcon_exit is also called from con_deinit stuff, and
there fbcon_has_exited prevents double-cleanup. But we can fix that
by properly resetting con2fb_map[] to all -1, which is used everywhere
else to indicate "no fb_info allocate to this console". With that
change the double-cleanup (which resulted in a module refcount underflow,
among other things) is prevented.

Aside: con2fb_map is a signed char, so don't register more than 128 fb_info
or hilarity will ensue.

v3: CI showed me that I still didn't fully understand what's going on
here. The leaked references in con2fb_map have been used upon
rebinding the fb console in fbcon_init. It worked because fbdev
unregistering still cleaned out con2fb_map, and reset it to info_idx.
If the last fbdev driver unregistered, then it also reset info_idx,
and unregistered the fbcon driver.

Imo that's all a bit fragile, so let's keep the con2fb_map reset to
-1, and in fbcon_init pick info_idx if we're starting fresh. That
means unbinding and rebinding will cleanse the mapping, but why are
you doing that if you want to retain the mapping, so should be fine.

Also, I think info_idx == -1 is impossible in fbcon_init - we
unregister the fbcon in that case. So catch&warn about that.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Yisheng Xie <ysxie@foxmail.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
---
 drivers/video/fbdev/core/fbcon.c | 39 +++++---------------------------
 1 file changed, 6 insertions(+), 33 deletions(-)

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 5424051c8e1a..622d336cfc81 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -112,7 +112,6 @@ static int softback_lines;
 static int first_fb_vc;
 static int last_fb_vc = MAX_NR_CONSOLES - 1;
 static int fbcon_is_default = 1; 
-static int fbcon_has_exited;
 static int primary_device = -1;
 static int fbcon_has_console_bind;
 
@@ -1050,7 +1049,6 @@ static const char *fbcon_startup(void)
 		info->var.bits_per_pixel);
 
 	fbcon_add_cursor_timer(info);
-	fbcon_has_exited = 0;
 	return display_desc;
 }
 
@@ -1064,9 +1062,13 @@ static void fbcon_init(struct vc_data *vc, int init)
 	int logo = 1, new_rows, new_cols, rows, cols, charcnt = 256;
 	int cap, ret;
 
-	if (info_idx == -1 || info == NULL)
+	if (WARN_ON(info_idx == -1))
 	    return;
 
+	if (con2fb_map[vc->vc_num] == -1)
+		con2fb_map[vc->vc_num] = info_idx;
+
+	info = registered_fb[con2fb_map[vc->vc_num]];
 	cap = info->flags;
 
 	if (logo_shown < 0 && console_loglevel <= CONSOLE_LOGLEVEL_QUIET)
@@ -3336,14 +3338,6 @@ static int fbcon_event_notify(struct notifier_block *self,
 	struct fb_blit_caps *caps;
 	int idx, ret = 0;
 
-	/*
-	 * ignore all events except driver registration and deregistration
-	 * if fbcon is not active
-	 */
-	if (fbcon_has_exited && !(action == FB_EVENT_FB_REGISTERED ||
-				  action == FB_EVENT_FB_UNREGISTERED))
-		goto done;
-
 	switch(action) {
 	case FB_EVENT_SUSPEND:
 		fbcon_suspended(info);
@@ -3396,7 +3390,6 @@ static int fbcon_event_notify(struct notifier_block *self,
 		fbcon_remap_all(idx);
 		break;
 	}
-done:
 	return ret;
 }
 
@@ -3443,9 +3436,6 @@ static ssize_t store_rotate(struct device *device,
 	int rotate, idx;
 	char **last = NULL;
 
-	if (fbcon_has_exited)
-		return count;
-
 	console_lock();
 	idx = con2fb_map[fg_console];
 
@@ -3468,9 +3458,6 @@ static ssize_t store_rotate_all(struct device *device,
 	int rotate, idx;
 	char **last = NULL;
 
-	if (fbcon_has_exited)
-		return count;
-
 	console_lock();
 	idx = con2fb_map[fg_console];
 
@@ -3491,9 +3478,6 @@ static ssize_t show_rotate(struct device *device,
 	struct fb_info *info;
 	int rotate = 0, idx;
 
-	if (fbcon_has_exited)
-		return 0;
-
 	console_lock();
 	idx = con2fb_map[fg_console];
 
@@ -3514,9 +3498,6 @@ static ssize_t show_cursor_blink(struct device *device,
 	struct fbcon_ops *ops;
 	int idx, blink = -1;
 
-	if (fbcon_has_exited)
-		return 0;
-
 	console_lock();
 	idx = con2fb_map[fg_console];
 
@@ -3543,9 +3524,6 @@ static ssize_t store_cursor_blink(struct device *device,
 	int blink, idx;
 	char **last = NULL;
 
-	if (fbcon_has_exited)
-		return count;
-
 	console_lock();
 	idx = con2fb_map[fg_console];
 
@@ -3668,9 +3646,6 @@ static void fbcon_exit(void)
 	struct fb_info *info;
 	int i, j, mapped;
 
-	if (fbcon_has_exited)
-		return;
-
 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
 	if (deferred_takeover) {
 		dummycon_unregister_output_notifier(&fbcon_output_nb);
@@ -3695,7 +3670,7 @@ static void fbcon_exit(void)
 		for (j = first_fb_vc; j <= last_fb_vc; j++) {
 			if (con2fb_map[j] == i) {
 				mapped = 1;
-				break;
+				con2fb_map[j] = -1;
 			}
 		}
 
@@ -3718,8 +3693,6 @@ static void fbcon_exit(void)
 				info->queue.func = NULL;
 		}
 	}
-
-	fbcon_has_exited = 1;
 }
 
 void __init fb_console_init(void)
-- 
2.20.1


  parent reply	other threads:[~2019-05-24  8:54 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  8:53 [PATCH 00/33] fbcon notifier begone! Daniel Vetter
2019-05-24  8:53 ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 01/33] dummycon: Sprinkle locking checks Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 02/33] fbdev: locking check for fb_set_suspend Daniel Vetter
2019-05-24  8:53 ` [PATCH 03/33] vt: might_sleep() annotation for do_blank_screen Daniel Vetter
2019-05-24  8:53 ` [PATCH 04/33] vt: More locking checks Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-27  7:08   ` Daniel Vetter
2019-05-27  7:08     ` Daniel Vetter
2019-05-27  7:22     ` Greg Kroah-Hartman
2019-05-24  8:53 ` [PATCH 05/33] fbdev/sa1100fb: Remove dead code Daniel Vetter
2019-05-24  8:53 ` [PATCH 06/33] fbdev/cyber2000: Remove struct display Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 07/33] fbdev/aty128fb: Remove dead code Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 08/33] fbcon: s/struct display/struct fbcon_display/ Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` Daniel Vetter [this message]
2019-05-25 15:38   ` [PATCH 09/33] fbcon: Remove fbcon_has_exited Sam Ravnborg
2019-05-25 15:38     ` Sam Ravnborg
2019-05-27  6:10     ` Daniel Vetter
2019-05-27  6:10       ` Daniel Vetter
2019-05-27  6:51       ` Sam Ravnborg
2019-05-27  6:51         ` Sam Ravnborg
2019-05-24  8:53 ` [PATCH 10/33] fbcon: call fbcon_fb_(un)registered directly Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 11/33] fbdev/sh_mobile: remove sh_mobile_lcdc_display_notify Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-25 15:01   ` Sam Ravnborg
2019-05-25 15:01     ` Sam Ravnborg
2019-05-27  6:13     ` Daniel Vetter
2019-05-27  6:52       ` Sam Ravnborg
2019-05-24  8:53 ` [PATCH 12/33] fbdev/omap: sysfs files can't disappear before the device is gone Daniel Vetter
2019-05-24  8:53 ` [PATCH 13/33] fbdev: " Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 14/33] staging/olpc: lock_fb_info can't fail Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-27  7:10   ` Daniel Vetter
2019-05-27  7:22     ` Greg KH
2019-05-27  7:22       ` Greg KH
2019-05-24  8:53 ` [PATCH 15/33] fbdev/atyfb: " Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 16/33] fbdev: lock_fb_info cannot fail Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 17/33] fbcon: call fbcon_fb_bind directly Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 18/33] fbdev: make unregister/unlink functions not fail Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 19/33] fbdev: unify unlink_framebuffer paths Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 20/33] fbdev/sh_mob: Remove fb notifier callback Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 21/33] fbdev: directly call fbcon_suspended/resumed Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 22/33] fbcon: Call fbcon_mode_deleted/new_modelist directly Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 23/33] fbdev: Call fbcon_get_requirement directly Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 24/33] Revert "backlight/fbcon: Add FB_EVENT_CONBLANK" Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24 13:14   ` Daniel Thompson
2019-05-24 13:14     ` Daniel Thompson
2019-05-24 13:14     ` Daniel Thompson
2019-05-24 15:28     ` Daniel Vetter
2019-05-24 15:28       ` Daniel Vetter
2019-05-27 10:59       ` Bartlomiej Zolnierkiewicz
2019-05-27 10:59         ` Bartlomiej Zolnierkiewicz
2019-05-24  8:53 ` [PATCH 25/33] fbmem: pull fbcon_fb_blanked out of fb_blank Daniel Vetter
2019-05-25 17:00   ` Sam Ravnborg
2019-05-25 17:00     ` Sam Ravnborg
2019-05-24  8:53 ` [PATCH 26/33] fbdev: remove FBINFO_MISC_USEREVENT around fb_blank Daniel Vetter
2019-05-24  8:53 ` [PATCH 27/33] fb: Flatten control flow in fb_set_var Daniel Vetter
2019-05-24  8:53 ` [PATCH 28/33] fbcon: replace FB_EVENT_MODE_CHANGE/_ALL with direct calls Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 29/33] vgaswitcheroo: call fbcon_remap_all directly Daniel Vetter
2019-05-24  8:53   ` Daniel Vetter
2019-05-24  8:53 ` [PATCH 30/33] fbcon: Call con2fb_map functions directly Daniel Vetter
2019-05-24  8:53 ` [PATCH 31/33] fbcon: Document what I learned about fbcon locking Daniel Vetter
2019-05-24  8:53 ` [PATCH 32/33] staging/olpc_dcon: Add drm conversion to TODO Daniel Vetter
2019-05-27  7:11   ` Daniel Vetter
2019-05-27  7:11     ` Daniel Vetter
2019-05-27  7:22     ` Greg KH
2019-05-24  8:53 ` [PATCH 33/33] backlight: simplify lcd notifier Daniel Vetter
2019-05-24 11:03 ` ✗ Fi.CI.CHECKPATCH: warning for fbcon notifier begone! (rev3) Patchwork
2019-05-24 11:18 ` ✗ Fi.CI.SPARSE: " Patchwork
2019-05-24 11:23 ` ✓ Fi.CI.BAT: success " Patchwork
2019-05-25 17:19 ` [PATCH 00/33] fbcon notifier begone! Sam Ravnborg
2019-05-27  7:17   ` Daniel Vetter
2019-05-27 11:56     ` Daniel Vetter
2019-05-25 17:24 ` ✗ Fi.CI.IGT: failure for fbcon notifier begone! (rev3) Patchwork
2019-05-26 15:34 ` ✗ Fi.CI.CHECKPATCH: warning for fbcon notifier begone! (rev4) Patchwork
2019-05-26 15:49 ` ✗ Fi.CI.SPARSE: " Patchwork
2019-05-26 15:53 ` ✓ Fi.CI.BAT: success " Patchwork
2019-05-27 11:02 ` ✓ Fi.CI.IGT: " Patchwork
  -- strict thread matches above, loose matches on Subject: below --
2019-05-28  9:02 [PATCH 00/33] fbcon notifier begone v3! Daniel Vetter
2019-05-28  9:02 ` [PATCH 09/33] fbcon: Remove fbcon_has_exited Daniel Vetter
2019-05-28  9:02   ` Daniel Vetter
2019-05-28  9:02   ` Daniel Vetter
2019-05-20  8:21 [PATCH 00/33] fbcon notifier begone! Daniel Vetter
2019-05-20  8:21 ` [PATCH 09/33] fbcon: Remove fbcon_has_exited Daniel Vetter
2019-05-20  8:21   ` Daniel Vetter

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