From: Qiujun Huang <hqjagain@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: mingo@redhat.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ring-buffer: Add rb_check_bpage in __rb_allocate_pages
Date: Wed, 14 Oct 2020 23:48:05 +0800 [thread overview]
Message-ID: <CAJRQjodMzSAJd23F=RRhR=d2H=D3vWMvCbU9JYdGNQ9MTkpmmw@mail.gmail.com> (raw)
In-Reply-To: <20201014113823.4296521d@gandalf.local.home>
On Wed, Oct 14, 2020 at 11:38 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 14 Oct 2020 23:16:14 +0800
> Qiujun Huang <hqjagain@gmail.com> wrote:
>
> > It may be better to check each page is aligned by 4 bytes. The 2
> > least significant bits of the address will be used as flags.
> >
> > Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
> > ---
> > kernel/trace/ring_buffer.c | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> > index 93ef0ab6ea20..9dec7d58b177 100644
> > --- a/kernel/trace/ring_buffer.c
> > +++ b/kernel/trace/ring_buffer.c
> > @@ -1420,7 +1420,8 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
> > return 0;
> > }
> >
> > -static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
> > +static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
> > + long nr_pages, struct list_head *pages, int cpu)
> > {
> > struct buffer_page *bpage, *tmp;
> > bool user_thread = current->mm != NULL;
> > @@ -1464,6 +1465,8 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
> > if (!bpage)
> > goto free_pages;
> >
> > + rb_check_bpage(cpu_buffer, bpage);
> > +
> >
>
> Why add it here, and not just add this check to the scan in
> rb_check_pages()?
rb_head_page_deactivate() in rb_check_pages() will clear the 2 LSB first.
>
> -- Steve
next prev parent reply other threads:[~2020-10-14 15:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 15:16 [PATCH] ring-buffer: Add rb_check_bpage in __rb_allocate_pages Qiujun Huang
2020-10-14 15:38 ` Steven Rostedt
2020-10-14 15:48 ` Qiujun Huang [this message]
2020-10-14 16:11 ` Steven Rostedt
2020-10-14 16:32 ` Qiujun Huang
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