path: root/fs/signalfd.c
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authorOleg Nesterov <oleg@redhat.com>2010-08-10 18:03:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-11 08:59:19 -0700
commitc7e49c1488ab20342eaaf38f1ca35a207f4c051d (patch)
tree43876a69cafbb49ce86f71ba5db88018ca7cc036 /fs/signalfd.c
parent13d7e3a2dba6a79589ed34dc0b9114d7b5ff9eab (diff)
ptrace: optimize exit_ptrace() for the likely case
exit_ptrace() takes tasklist_lock unconditionally. We need this lock to avoid the race with ptrace_traceme(), it acts as a barrier. Change its caller, forget_original_parent(), to call exit_ptrace() under tasklist_lock. Change exit_ptrace() to drop and reacquire this lock if needed. This allows us to add the fastpath list_empty(ptraced) check. In the likely no-tracees case exit_ptrace() just returns and we avoid the lock() + unlock() sequence. "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> suggested to add this check, and he reports that this change adds about 11% improvement in some tests. Suggested-and-tested-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> 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>
Diffstat (limited to 'fs/signalfd.c')
0 files changed, 0 insertions, 0 deletions