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Message-ID: <YgLJqeRX0BWF4j29@phenom.ffwll.local> Date: Tue, 8 Feb 2022 20:51:05 +0100 From: Daniel Vetter <daniel@...ll.ch> To: Sam Ravnborg <sam@...nborg.org> Cc: DRI Development <dri-devel@...ts.freedesktop.org>, linux-fbdev@...r.kernel.org, Du Cheng <ducheng2@...il.com>, Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>, Intel Graphics Development <intel-gfx@...ts.freedesktop.org>, LKML <linux-kernel@...r.kernel.org>, Claudio Suarez <cssk@...-c.es>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Daniel Vetter <daniel.vetter@...el.com> Subject: Re: [Intel-gfx] [PATCH 11/21] fbcon: Extract fbcon_open/release helpers On Tue, Feb 08, 2022 at 07:24:03PM +0100, Sam Ravnborg wrote: > Hi Daniel, > > On Tue, Feb 08, 2022 at 02:48:29PM +0100, Daniel Vetter wrote: > > On Thu, Feb 03, 2022 at 10:15:14PM +0100, Sam Ravnborg wrote: > > > Hi Daniel, > > > > > > On Mon, Jan 31, 2022 at 10:05:42PM +0100, Daniel Vetter wrote: > > > > There's two minor behaviour changes in here: > > > > - in error paths we now consistently call fb_ops->fb_release > > > > - fb_release really can't fail (fbmem.c ignores it too) and there's no > > > > reasonable cleanup we can do anyway. > > > > > > > > Signed-off-by: Daniel Vetter <daniel.vetter@...el.com> > > > > Cc: Daniel Vetter <daniel@...ll.ch> > > > > Cc: Claudio Suarez <cssk@...-c.es> > > > > Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> > > > > Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> > > > > Cc: Du Cheng <ducheng2@...il.com> > > > > --- > > > > drivers/video/fbdev/core/fbcon.c | 107 +++++++++++++++---------------- > > > > 1 file changed, 53 insertions(+), 54 deletions(-) > > > > > > > > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c > > > > index fa30e1909164..eea2ee14b64c 100644 > > > > --- a/drivers/video/fbdev/core/fbcon.c > > > > +++ b/drivers/video/fbdev/core/fbcon.c > > > > @@ -680,19 +680,37 @@ static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount) > > > > > > > > #endif /* CONFIG_MISC_TILEBLITTING */ > > > > > > > > +static int fbcon_open(struct fb_info *info) > > > > +{ > > > > + if (!try_module_get(info->fbops->owner)) > > > > + return -ENODEV; > > > > + > > > > + if (info->fbops->fb_open && > > > > + info->fbops->fb_open(info, 0)) { > > > > + module_put(info->fbops->owner); > > > > + return -ENODEV; > > > > + } > > > > + > > > > + return 0; > > > > +} > > > > + > > > > +static void fbcon_release(struct fb_info *info) > > > > +{ > > > > + if (info->fbops->fb_release) > > > > + info->fbops->fb_release(info, 0); > > > > + > > > > + module_put(info->fbops->owner); > > > > +} > > > > > > > > static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info, > > > > int unit, int oldidx) > > > > { > > > > struct fbcon_ops *ops = NULL; > > > > - int err = 0; > > > > - > > > > - if (!try_module_get(info->fbops->owner)) > > > > - err = -ENODEV; > > > > + int err; > > > > > > > > - if (!err && info->fbops->fb_open && > > > > - info->fbops->fb_open(info, 0)) > > > > - err = -ENODEV; > > > > + err = fbcon_open(info); > > > > + if (err) > > > > + return err; > > > > > > > > if (!err) { > > > > ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL); > > > > @@ -713,7 +731,7 @@ static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info, > > > > > > > > if (err) { > > > > con2fb_map[unit] = oldidx; > > > > - module_put(info->fbops->owner); > > > > + fbcon_release(info); > > > > } > > > > > > > > return err; > > > > @@ -724,45 +742,34 @@ static int con2fb_release_oldinfo(struct vc_data *vc, struct fb_info *oldinfo, > > > > int oldidx, int found) > > > > { > > > > struct fbcon_ops *ops = oldinfo->fbcon_par; > > > > - int err = 0, ret; > > > > + int ret; > > > > > > > > - if (oldinfo->fbops->fb_release && > > > > - oldinfo->fbops->fb_release(oldinfo, 0)) { > > > > - con2fb_map[unit] = oldidx; > > > The old code assigns con2fb_map[unit] before is calls > > > newinfo->fbops->fb_release). > > > I wonder if there can be any callback to fbcon where the value > > > of con2fb_map[unit] matters? > > > > It's all protected by console_lock, so other threads cannot see the > > inconsistent state. > > > > Essentially everything in fbcon.c is protected by console_lock(). > > > > Do you want me to hammer this in somewhere (maybe in the commit message), > > or good enough for your ack? > > No need to spell it out more. I think this was a very good question, since I had to spend a few minutes figuring out what exactly and why I've done it too. So I'll add this explainer, it really should have been in the commit message! > Add my a-b and apply it. Well I need to resend, since there was a minor change due to rebasing on top of Helge's fbcon scrolling patches instead of mine. Thanks for your review -Daniel > > Sam -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
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