2014-07-14 04:19:57

by Wang Nan

Subject: [PATCH] ftrace: Do not copy old hash when resetting.

If we are going to reset hash, we don't need to duplicate old hash
and remove every entries right after allocation.

Signed-off-by: Wang Nan <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Ingo Molnar <[email protected]>
---
kernel/trace/ftrace.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 5b372e3..52d6931 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3471,14 +3471,16 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
else
orig_hash = &ops->notrace_hash;

- hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+ if (!reset)
+ hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+ else
+ hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
+
if (!hash) {
ret = -ENOMEM;
goto out_regex_unlock;
}

- if (reset)
- ftrace_filter_reset(hash);
if (buf && !ftrace_match_records(hash, buf, len)) {
ret = -EINVAL;
goto out_regex_unlock;
--
1.8.4

2014-07-14 12:21:29

by Steven Rostedt

Subject: Re: [PATCH] ftrace: Do not copy old hash when resetting.

On Mon, 14 Jul 2014 12:10:00 +0800
Wang Nan <[email protected]> wrote:

> If we are going to reset hash, we don't need to duplicate old hash
> and remove every entries right after allocation.
>
> Signed-off-by: Wang Nan <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> ---
> kernel/trace/ftrace.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 5b372e3..52d6931 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -3471,14 +3471,16 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
> else
> orig_hash = &ops->notrace_hash;
>
> - hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
> + if (!reset)
> + hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
> + else
> + hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);

I'm fine with this patch, but please swap the if statement above. I
prefer the if condition being positive if there's also an else
statement above. That is:

if (reset)
hash = alloc_ftrace_hash();
else
hash = alloc_and_copy_ftrace_hash();

-- Steve

> +
> if (!hash) {
> ret = -ENOMEM;
> goto out_regex_unlock;
> }
>
> - if (reset)
> - ftrace_filter_reset(hash);
> if (buf && !ftrace_match_records(hash, buf, len)) {
> ret = -EINVAL;
> goto out_regex_unlock;

2014-07-18 04:45:04

by Wang Nan

Subject: Re: [PATCH] ftrace: Do not copy old hash when resetting.

Hi Steve,

What's your opinion on my v2 patch ( https://lkml.org/lkml/2014/7/14/839 )?

I have swapped if consitions following your suggestion.

On 2014/7/14 12:10, Wang Nan wrote:
> If we are going to reset hash, we don't need to duplicate old hash
> and remove every entries right after allocation.
>
> Signed-off-by: Wang Nan <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> ---
> kernel/trace/ftrace.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 5b372e3..52d6931 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -3471,14 +3471,16 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
> else
> orig_hash = &ops->notrace_hash;
>
> - hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
> + if (!reset)
> + hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
> + else
> + hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
> +
> if (!hash) {
> ret = -ENOMEM;
> goto out_regex_unlock;
> }
>
> - if (reset)
> - ftrace_filter_reset(hash);
> if (buf && !ftrace_match_records(hash, buf, len)) {
> ret = -EINVAL;
> goto out_regex_unlock;
>

2014-07-18 12:04:33

by Steven Rostedt

Subject: Re: [PATCH] ftrace: Do not copy old hash when resetting.

On Fri, 18 Jul 2014 12:44:18 +0800
Wang Nan <[email protected]> wrote:

> Hi Steve,
>
> What's your opinion on my v2 patch ( https://lkml.org/lkml/2014/7/14/839 )?
>
> I have swapped if consitions following your suggestion.
>

Bah I didn't see it.

Damn Claws mail, I need to figure out why the f*ck it randomly marks
all my email as read. This has caused me to miss a few important emails
recently :-(

It looks fine, I've now marked it as todo that way I'll see it to pull
it in for 3.17. Thanks,

-- Steve


> On 2014/7/14 12:10, Wang Nan wrote:
> > If we are going to reset hash, we don't need to duplicate old hash
> > and remove every entries right after allocation.
> >
> > Signed-off-by: Wang Nan <[email protected]>
> > Cc: Steven Rostedt <[email protected]>
> > Cc: Ingo Molnar <[email protected]>
> > ---
> > kernel/trace/ftrace.c | 8 +++++---
> > 1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index 5b372e3..52d6931 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -3471,14 +3471,16 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
> > else
> > orig_hash = &ops->notrace_hash;
> >
> > - hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
> > + if (!reset)
> > + hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
> > + else
> > + hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
> > +
> > if (!hash) {
> > ret = -ENOMEM;
> > goto out_regex_unlock;
> > }
> >
> > - if (reset)
> > - ftrace_filter_reset(hash);
> > if (buf && !ftrace_match_records(hash, buf, len)) {
> > ret = -EINVAL;
> > goto out_regex_unlock;
> >
>