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check_unshare_flags: kill the bogus CLONE_SIGHAND/sig->count check 

check_unshare_flags(CLONE_SIGHAND) adds CLONE_THREAD to *flags_ptr if the
task is multithreaded to ensure unshare_thread() will fail.

Not only this is a bit strange way to return the error, this is absolutely
meaningless.  If signal->count > 1 then sighand->count must be also > 1,
and unshare_sighand() will fail anyway.

In fact, all CLONE_THREAD/SIGHAND/VM checks inside sys_unshare() do not
look right.  Fortunately this code doesn't really work anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2010-05-26 14:43:21 -07:00 committed by Linus Torvalds
parent 97101eb41d
commit 6e1be45aa6
1 changed files with 0 additions and 8 deletions
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8
kernel/fork.c
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@ -1517,14 +1517,6 @@ static void check_unshare_flags(unsigned long *flags_ptr)
if (*flags_ptr & CLONE_VM)
*flags_ptr |= CLONE_SIGHAND;
/*
* If unsharing signal handlers and the task was created
* using CLONE_THREAD, then must unshare the thread
*/
if ((*flags_ptr & CLONE_SIGHAND) &&
(atomic_read(&current->signal->count) > 1))
*flags_ptr |= CLONE_THREAD;
/*
* If unsharing namespace, must also unshare filesystem information.
*/