[00/21] some fbcon patches, mostly locking

Message

Daniel Vetter Jan. 31, 2022, 9:05 p.m. UTC

Hi all,

This took way longer than I hoped, but well I got lost in head-scratching
locking problems. Anyway ended up typing a pile of fbcon patches. Rough
overview:

- MAINTAINER entry for fbdev core in drm-misc, with the usual group
  maintainering

- The reverts, but with a compile time option. I looked into combining
  this with the RFC from Helge, but it looked like worse than either
  approach, so I've kept mine. I think merging either is fine, no personal
  stake here on the bikeshed color.

- The real distraction, aka a bunch of cleanups and mostly locking work
  for fbcon. I managed to ditch at least one locking FIXME from fbcon.c.

The bad news that I spent a bunch more time pondering about the bigger
locking issues in fbcon.c, and I think as-is they're unfixable. We need
the threaded printk support to land first, so that we're not adding
lock_fb_info() to all printk() contexts. Because that just cannot work.

That also means we'll likely have another fbcon regression to face, in the
form of worse oops printing ability. And that one I don't think we can fix
with clever application of #ifdef, because changing locking rules at
compile time in fundamental ways is just not a very good idea.

Anyway, testing, review, feedback and all that very much welcome, as
usual.

Cheers, Daniel

Daniel Vetter (21):
  MAINTAINERS: Add entry for fbdev core
  fbcon: Resurrect fbcon accelerated scrolling code
  fbcon: Restore fbcon scrolling acceleration
  fbcon: delete a few unneeded forward decl
  fbcon: Introduce wrapper for console->fb_info lookup
  fbcon: delete delayed loading code
  fbdev/sysfs: Fix locking
  fbcon: Use delayed work for cursor
  fbcon: Replace FBCON_FLAGS_INIT with a boolean
  fb: Delete fb_info->queue
  fbcon: Extract fbcon_open/release helpers
  fbcon: Ditch error handling for con2fb_release_oldinfo
  fbcon: move more common code into fb_open()
  fbcon: use lock_fb_info in fbcon_open/release
  fbcon: Consistently protect deferred_takeover with console_lock()
  fbcon: Move console_lock for register/unlink/unregister
  fbcon: Move more code into fbcon_release
  fbcon: untangle fbcon_exit
  fbcon: Maintain a private array of fb_info
  Revert "fbdev: Prevent probing generic drivers if a FB is already
    registered"
  fbdev: Make registered_fb[] private to fbmem.c

 Documentation/gpu/todo.rst              |   13 +-
 MAINTAINERS                             |    6 +
 drivers/video/console/Kconfig           |   11 +
 drivers/video/fbdev/core/bitblit.c      |   16 +
 drivers/video/fbdev/core/fbcon.c        | 1072 +++++++++++++++++------
 drivers/video/fbdev/core/fbcon.h        |   67 +-
 drivers/video/fbdev/core/fbcon_ccw.c    |   28 +-
 drivers/video/fbdev/core/fbcon_cw.c     |   28 +-
 drivers/video/fbdev/core/fbcon_rotate.h |   21 +
 drivers/video/fbdev/core/fbcon_ud.c     |   37 +-
 drivers/video/fbdev/core/fbmem.c        |   35 +-
 drivers/video/fbdev/core/fbsysfs.c      |    2 +
 drivers/video/fbdev/core/tileblit.c     |   16 +
 drivers/video/fbdev/efifb.c             |   11 -
 drivers/video/fbdev/simplefb.c          |   11 -
 drivers/video/fbdev/skeletonfb.c        |   12 +-
 include/linux/fb.h                      |   10 +-
 17 files changed, 1017 insertions(+), 379 deletions(-)