diff options
author | Jeff Dike <jdike@addtoit.com> | 2007-02-10 01:43:52 -0800 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-02-11 10:51:21 -0800 |
commit | d79a580936396bbcd2f4fae2c6215f9cf81e3c0d (patch) | |
tree | 72c91c7475e2562c5459c4d6d0499cdd671e0b50 /arch/um/include/chan_kern.h | |
parent | 5cf885d01f30be710a339976c485f92bb8a8946d (diff) |
[PATCH] uml: console locking fixes
Clean up the console driver locking. There are various problems here,
including sleeping under a spinlock and spinlock recursion, some of which are
fixed here. This patch deals with the locking involved with opens and closes.
The problem is that an mconsole request to change a console's configuration
can race with an open. Changing a configuration should only be done when a
console isn't opened. Also, an open must be looking at a stable
configuration. In addition, a get configuration request must observe the same
locking since it must also see a stable configuration. With the old locking,
it was possible for this to hang indefinitely in some cases because open would
block for a long time waiting for a connection from the host while holding the
lock needed by the mconsole request.
As explained in the long comment, this is fixed by adding a spinlock for the
use count and configuration and a mutex for the actual open and close.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/include/chan_kern.h')
0 files changed, 0 insertions, 0 deletions