From: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Date: Thu, 6 Nov 2008 20:53:37 +0000 (-0800)
Subject: fbdev: fix fb_compat_ioctl() deadlocks
X-Git-Tag: v2.6.28-rc4~59
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a684e7d33096892093456dd56a582cfc3bfad648;p=pandora-kernel.git

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 <Geert.Uytterhoeven@sonycom.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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