[PATCH] override RLIMIT_SIGPENDING for non-RT signals

I can read POSIX to say that the siginfo_t data must be available when
`kill' was used, as well.  This patch makes it allocate the siginfo_t, even
when that exceeds {RLIMIT_SIGPENDING}, for any non-RT signal (< SIGRTMIN)
not sent by sigqueue (actually, any signal that couldn't have been faked by
a sigqueue call).  Of course, in an extreme memory shortage situation, you
are SOL and violate POSIX a little before you die horribly from being out
of memory anyway.

The LEGACY_QUEUE logic already ensures that, for non-RT signals, at most
one is ever on the queue.  So there really is no risk at all of unbounded
resource consumption; the usage can reach {RLIMIT_SIGPENDING} + 31, is all.

It's already the case that the limit can be exceeded by (in theory) up to
{RLIMIT_NPROC}-1 in race conditions because the bump and the limit check
are not atomic.  (Obviously you can only get anywhere near that many with
assloads of preemption, but exceeding it by a few is not too unlikely.)
This patch also fixes that accounting so that it should not be possible to
exceed {RLIMIT_SIGPENDING} + SIGRTMIN-1 queue items per user in races.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

0 files changed, 0 insertions, 0 deletions