ptrace: simplify ptrace_exit()->ignoring_children() path
commit6d69cb87f05eef3b02370b2f7bae608ad2301a00
authorOleg Nesterov <oleg@redhat.com>
Thu, 2 Apr 2009 23:58:12 +0000 (2 16:58 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 3 Apr 2009 02:04:59 +0000 (2 19:04 -0700)
tree69f38afc49df51a1a75fc5c7792ced6888af329d
parent95c3eb76dc07fd81289888ffc42948196b34b444
ptrace: simplify ptrace_exit()->ignoring_children() path

ignoring_children() takes parent->sighand->siglock and checks
k_sigaction[SIGCHLD] atomically.  But this buys nothing, we can't get the
"really" wrong result even if we race with sigaction(SIGCHLD).  If we read
the "stale" sa_handler/sa_flags we can pretend it was changed right after
the check.

Remove spin_lock(->siglock), and kill "int ign" which caches the result of
ignoring_children() which becomes rather trivial.

Perhaps it makes sense to export this helper, do_notify_parent() can use
it too.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c