lkml.org 
[lkml]   [2010]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH 2/6] trace syscalls: Remove redundant syscall_nr checks
From
Date
On Tue, 2010-12-07 at 15:29 +1100, Ian Munsie wrote:
> From: Ian Munsie <imunsie@au1.ibm.com>
>
> With the ftrace events now checking if the syscall_nr is valid upon
> initialisation, there is no need to verify it when registering and
> unregistering the events, so remove the check.

I still like to keep these checks. I don't mind redundant checks that
are in slow paths, as they may catch a bug on a change in the future.

What you could do is change these to:

if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))

-- Steve

>
> Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
> ---
> kernel/trace/trace_syscalls.c | 9 +--------
> 1 files changed, 1 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
> index 14f4c02..5e34b49 100644
> --- a/kernel/trace/trace_syscalls.c
> +++ b/kernel/trace/trace_syscalls.c
> @@ -367,8 +367,6 @@ int reg_event_syscall_enter(struct ftrace_event_call *call)
> int num;
>
> num = ((struct syscall_metadata *)call->data)->syscall_nr;
> - if (num < 0 || num >= NR_syscalls)
> - return -ENOSYS;
> mutex_lock(&syscall_trace_lock);
> if (!sys_refcount_enter)
> ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
> @@ -385,8 +383,6 @@ void unreg_event_syscall_enter(struct ftrace_event_call *call)
> int num;
>
> num = ((struct syscall_metadata *)call->data)->syscall_nr;
> - if (num < 0 || num >= NR_syscalls)
> - return;
> mutex_lock(&syscall_trace_lock);
> sys_refcount_enter--;
> clear_bit(num, enabled_enter_syscalls);
> @@ -401,8 +397,7 @@ int reg_event_syscall_exit(struct ftrace_event_call *call)
> int num;
>
> num = ((struct syscall_metadata *)call->data)->syscall_nr;
> - if (num < 0 || num >= NR_syscalls)
> - return -ENOSYS;
> +
> mutex_lock(&syscall_trace_lock);
> if (!sys_refcount_exit)
> ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
> @@ -419,8 +414,6 @@ void unreg_event_syscall_exit(struct ftrace_event_call *call)
> int num;
>
> num = ((struct syscall_metadata *)call->data)->syscall_nr;
> - if (num < 0 || num >= NR_syscalls)
> - return;
> mutex_lock(&syscall_trace_lock);
> sys_refcount_exit--;
> clear_bit(num, enabled_exit_syscalls);




\
 
 \ /
  Last update: 2010-12-07 15:57    [W:0.035 / U:0.508 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site