[PATCH] ptmx: fix duplicate idr_remove
Remove duplicate call to idr_remove() in ptmx_open.
Error during open can result in call to release_dev() followed by call to
idr_remove(). release_dev already calls idr_remove so the second call can
cause a stack dump in idr_remove()->sub_remove() flagging an attempt to
release an already released entry.
I reproduces this on a machine with a misconfigured X server (attempting to
restart multiple times rapidly) getting the same error as the 1st link
below.
This also seems to be related to:
http://marc.theaimsgroup.com/?l=selinux&m=110536513426735&w=2
http://marc.theaimsgroup.com/?l=selinux&m=110596994916785&w=2
The stack dump can occur on close (as well as open) as shown
in the 1st instance above, possible from something like:
process A - open (index=0), open fail to out1,
release_dev calls idr_remove (index 0), down(sem) sleeps
process B - open (index=0), open OK (idr allocated)
process A - wake and call idr_remove on index 0
...
process B - close, release_dev, stack dump on idr_remove (index=0)
because entry already removed
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 file changed