linux/include
Oleg Nesterov ea6d290ca3 signals: make task_struct->signal immutable/refcountable
We have a lot of problems with accessing task_struct->signal, it can
"disappear" at any moment.  Even current can't use its ->signal safely
after exit_notify().  ->siglock helps, but it is not convenient, not
always possible, and sometimes it makes sense to use task->signal even
after this task has already dead.

This patch adds the reference counter, sigcnt, into signal_struct.  This
reference is owned by task_struct and it is dropped in
__put_task_struct().  Perhaps it makes sense to export
get/put_signal_struct() later, but currently I don't see the immediate
reason.

Rename __cleanup_signal() to free_signal_struct() and unexport it.  With
the previous changes it does nothing except kmem_cache_free().

Change __exit_signal() to not clear/free ->signal, it will be freed when
the last reference to any thread in the thread group goes away.

Note:
	- when the last thead exits signal->tty can point to nowhere, see
	  the next patch.

	- with or without this patch signal_struct->count should go away,
	  or at least it should be "int nr_threads" for fs/proc. This will
	  be addressed later.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-05-27 09:12:46 -07:00
..
acpi ACPICA: Update version to 20100428. 2010-05-06 03:05:54 -04:00
asm-generic gpiolib: introduce set_debounce method 2010-05-27 09:12:42 -07:00
crypto crypto: skcipher - Add ablkcipher_walk interfaces 2010-05-19 14:13:07 +10:00
drm Merge branch 'drm-for-2.6.35' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2010-05-21 11:14:52 -07:00
keys
linux signals: make task_struct->signal immutable/refcountable 2010-05-27 09:12:46 -07:00
math-emu
media V4L/DVB: v4l2-subdev.h: Add support for enum_dv_preset 2010-05-19 12:59:01 -03:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2010-05-25 16:59:51 -07:00
pcmcia pcmcia: remove unused mem_op.h 2010-05-10 10:23:20 +02:00
rdma IB/core: Allow device-specific per-port sysfs files 2010-05-21 10:34:44 -07:00
rxrpc
scsi [SCSI] libfc: Move the port_id into lport 2010-05-16 22:22:34 -04:00
sound Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6 2010-05-20 09:41:44 -07:00
trace Merge branch 'kvm-updates/2.6.35' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2010-05-21 17:16:21 -07:00
video fbdev: move FBIO_WAITFORVSYNC to linux/fb.h 2010-05-25 08:07:09 -07:00
xen
Kbuild