fbdev: fix fb_compat_ioctl() deadlocks

commit 3e680aae4e53ab54cdbb0c29257dae0cbb158e1c ("fb: convert
lock/unlock_kernel() into local fb mutex") introduced several deadlocks
in the fb_compat_ioctl() path, as mutex_lock() doesn't allow recursion,
unlike lock_kernel().  This broke frame buffer applications on 64-bit
systems with a 32-bit userland.

commit 120a37470c2831fea49fdebaceb5a7039f700ce6 ("framebuffer compat_ioctl
deadlock") fixed one of the deadlocks.

This patch fixes the remaining deadlocks:
  - Revert commit 120a37470c2831fea49fdebaceb5a7039f700ce6,
  - Extract the core logic of fb_ioctl() into a new function do_fb_ioctl(),
  - Change all callsites of fb_ioctl() where info->lock is already held to
    call do_fb_ioctl() instead,
  - Add sparse annotations to all routines that take info->lock.

Signed-off-by: Geert Uytterhoeven <[email protected]>
Cc: Mikulas Patocka <[email protected]>
Cc: Krzysztof Helt <[email protected]>
Cc: Alan Cox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions