tracing: Fix syscall_*regfunc() vs copy_process() race
authorOleg Nesterov <oleg@redhat.com>
Sun, 13 Apr 2014 18:58:54 +0000 (20:58 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 7 Jul 2014 01:54:16 +0000 (18:54 -0700)
commite6bc60b8fb412b38db86bc1351f2ce40ad31d0e0
tree7fa6f63114bf298bebe1833f5966a5d76d6d727f
parentc5bce73649b8a164990182b46185197f3d424f41
tracing: Fix syscall_*regfunc() vs copy_process() race

commit 4af4206be2bd1933cae20c2b6fb2058dbc887f7c upstream.

syscall_regfunc() and syscall_unregfunc() should set/clear
TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race
with copy_process() and miss the new child which was not added to
the process/thread lists yet.

Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT
under tasklist.

Link: http://lkml.kernel.org/p/20140413185854.GB20668@redhat.com
Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints"
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
include/trace/syscall.h
kernel/fork.c