tracing/syscalls: Early terminate search for sys_ni_syscall

Many system calls are unimplemented and mapped to sys_ni_syscall, but at
boot ftrace would still search through every syscall metadata entry for
a match which wouldn't be there.

This patch adds causes the search to terminate early if the system call
is not mapped.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
LKML-Reference: <1296703645-18718-7-git-send-email-imunsie@au1.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 86a23e7de031fe1f9d21bab64e1c8080729ac6df..ee7b5a0bb9f87c1b9abb5964bfd4c54fd99ccb2d 100644 (file)
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -85,6 +85,9 @@ find_syscall_meta(unsigned long syscall)
        stop = __stop_syscalls_metadata;
        kallsyms_lookup(syscall, NULL, NULL, NULL, str);
 
+       if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
+               return NULL;
+
        for ( ; start < stop; start++) {
                if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
                        return *start;