]> git.baikalelectronics.ru Git - kernel.git/commit
signal: allow to send any siginfo to itself
authorAndrey Vagin <avagin@openvz.org>
Thu, 28 Feb 2013 01:03:12 +0000 (17:03 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 28 Feb 2013 03:10:11 +0000 (19:10 -0800)
commitd367d3b8d24e37b0360d75eec89c3a8b03962ba2
treed8a7316bbb8c83882f69952b145dfc46962b8265
parenta7a3f7e56505d16b3ff6fb0a5f9e042601f98baf
signal: allow to send any siginfo to itself

The idea is simple.  We need to get the siginfo for each signal on
checkpointing dump, and then return it back on restore.

The first problem is that the kernel doesn't report complete siginfos to
userspace.  In a signal handler the kernel strips SI_CODE from siginfo.
When a siginfo is received from signalfd, it has a different format with
fixed sizes of fields.  The interface of signalfd was extended.  If a
signalfd is created with the flag SFD_RAW, it returns siginfo in a raw
format.

rt_sigqueueinfo looks suitable for restoring signals, but it can't send
siginfo with a positive si_code, because these codes are reserved for
the kernel.  In the real world each person has right to do anything with
himself, so I think a process should able to send any siginfo to itself.

This patch:

The kernel prevents sending of siginfo with positive si_code, because
these codes are reserved for kernel.  I think we can allow a task to
send such a siginfo to itself.  This operation should not be dangerous.

This functionality is required for restoring signals in
checkpoint/restart.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/signal.c