[tip:perf/core] tracing/syscalls: Early terminate search for sys_ni_syscall

[tip-bot for Ian Munsie]

Commit-ID:  ae07f551c42d6e4162436ca452a199deac9dab4d
Gitweb:     http://git.kernel.org/tip/ae07f551c42d6e4162436ca452a199deac9dab4d
Author:     Ian Munsie <imunsie@xxxxxxxxxxx>
AuthorDate: Thu, 3 Feb 2011 14:27:25 +1100
Committer:  Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Mon, 7 Feb 2011 21:30:14 -0500

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@xxxxxxxxxxx>
LKML-Reference: <1296703645-18718-7-git-send-email-imunsie@xxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace_syscalls.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 86a23e7..ee7b5a0 100644
--- 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;
--
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