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From: Ian Munsie on 23 Jun 2010 06:10
From: Ian Munsie <imunsie(a)au1.ibm.com>

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(a)au1.ibm.com>
---
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 264441e..58ef002 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -95,6 +95,9 @@ static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
stop = (struct syscall_metadata *)__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;
--
1.7.1

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