From de29ae5c092bd9a5360cfabf174b0f783248d278 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Tue, 28 May 2019 11:02:56 +0200 Subject: fbmem: pull fbcon_fb_blanked out of fb_blank MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There's a callchain of: fbcon_fb_blanked -> do_(un)blank_screen -> consw->con_blank -> fbcon_blank -> fb_blank Things don't go horribly wrong because the BKL console_lock safes the day, but that's about it. And the seeming recursion is broken in 2 ways: - Starting from the fbdev ioctl we set FBINFO_MISC_USEREVENT, which tells the fbcon_blank code to not call fb_blank. This was required to not deadlock when recursing on the fb_notifier_chain mutex. - Starting from the con_blank hook we're getting saved by the console_blanked checks in do_blank/unblank_screen. Or at least that's my theory. Anyway, recursion isn't awesome, so let's stop it. Breaking the recursion avoids the need to be in the FBINFO_MISC_USEREVENT critical section, so lets move it out of that too. The astute reader will notice that fb_blank seems to require lock_fb_info(), which the fbcon code seems to ignore. I have no idea how to fix that problem, so let's keep ignoring it. v2: I forgot the sysfs blanking code. v3: Fix typo in callchain in the commmit message (Sam). Signed-off-by: Daniel Vetter Reviewed-by: Sam Ravnborg Reviewed-by: Maarten Lankhorst Cc: Sam Ravnborg Cc: Daniel Vetter Cc: Bartlomiej Zolnierkiewicz Cc: "Michał Mirosław" Cc: Peter Rosin Cc: Hans de Goede Cc: Mikulas Patocka Cc: Rob Clark Link: https://patchwork.freedesktop.org/patch/msgid/20190528090304.9388-26-daniel.vetter@ffwll.ch --- drivers/video/fbdev/core/fbmem.c | 4 +++- drivers/video/fbdev/core/fbsysfs.c | 8 ++++++-- 2 files changed, 9 insertions(+), 3 deletions(-) (limited to 'drivers/video') diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 9366fbe99a58..d6713dce9e31 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1068,7 +1068,6 @@ fb_blank(struct fb_info *info, int blank) event.data = ␣ early_ret = fb_notifier_call_chain(FB_EARLY_EVENT_BLANK, &event); - fbcon_fb_blanked(info, blank); if (info->fbops->fb_blank) ret = info->fbops->fb_blank(blank, info); @@ -1198,6 +1197,9 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, info->flags |= FBINFO_MISC_USEREVENT; ret = fb_blank(info, arg); info->flags &= ~FBINFO_MISC_USEREVENT; + + /* might again call into fb_blank */ + fbcon_fb_blanked(info, arg); unlock_fb_info(info); console_unlock(); break; diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index f80d5b3a7797..6e39066774a6 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -301,12 +302,15 @@ static ssize_t store_blank(struct device *device, { struct fb_info *fb_info = dev_get_drvdata(device); char *last = NULL; - int err; + int err, arg; + arg = simple_strtoul(buf, &last, 0); console_lock(); fb_info->flags |= FBINFO_MISC_USEREVENT; - err = fb_blank(fb_info, simple_strtoul(buf, &last, 0)); + err = fb_blank(fb_info, arg); fb_info->flags &= ~FBINFO_MISC_USEREVENT; + /* might again call into fb_blank */ + fbcon_fb_blanked(fb_info, arg); console_unlock(); if (err < 0) return err; -- cgit v1.2.3-59-g8ed1b