From: Petr Mladek <pmladek@suse.cz>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jiri Kosina <jkosina@suse.cz>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC][PATCH 08/12 v3] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
Date: Wed, 5 Nov 2014 17:51:25 +0100 [thread overview]
Message-ID: <20141105165125.GJ4570@pathway.suse.cz> (raw)
In-Reply-To: <20141104160222.644881406@goodmis.org>
On Tue 2014-11-04 10:52:45, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
>
> Add two helper functions; seq_buf_get_buf() and seq_buf_commit() that
> are used by seq_buf_path(). This makes the code similar to the
> seq_file: seq_path() function, and will help to be able to consolidate
> the functions between seq_file and trace_seq.
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
> include/linux/seq_buf.h | 40 ++++++++++++++++++++++++++++++++++++++++
> kernel/trace/seq_buf.c | 7 +++----
> 2 files changed, 43 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> index 3cd25038cb5e..10c17c61c7a4 100644
> --- a/include/linux/seq_buf.h
> +++ b/include/linux/seq_buf.h
> @@ -55,6 +55,46 @@ seq_buf_set_overflow(struct seq_buf *s)
> s->len = s->size + 1;
> }
>
> +/**
> + * seq_buf_get_buf - get buffer to write arbitrary data to
> + * @s: the seq_buf handle
> + * @bufp: the beginning of the buffer is stored here
> + *
> + * Return the number of bytes available in the buffer, or zero if
> + * there's no space.
> + */
> +static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
> +{
> + BUG_ON(s->len > s->size + 1);
> + if (s->len < s->size) {
> + *bufp = s->buffer + s->len;
> + return s->size - s->len;
> + }
> + *bufp = NULL;
> + return 0;
> +}
> +
> +/**
> + * seq_buf_commit - commit data to the buffer
> + * @s: the seq_buf handle
> + * @num: the number of bytes to commit
> + *
> + * Commit @num bytes of data written to a buffer previously acquired
> + * by seq_buf_get. To signal an error condition, or that the data
> + * didn't fit in the available space, pass a negative @num value.
> + */
> +static inline void seq_buf_commit(struct seq_buf *s, int num)
> +{
> + if (num < 0) {
> + s->len = s->size;
I guess that you want to get the buffer into an overflow state. If
yes, it should be:
s->len = s->size + 1;
or even better
seq_buf_set_overflow(s);
Note that this whole patch depends on the decision about the 7th patch
("tracing: Have seq_buf use full buffer").
It might make sense to move the SEQ_BUF_LEFT, SEQ_BUF_USED macros to
this header and use them in these two function. Or move the functions
to seq_file.c.
Best Regards,
Petr
next prev parent reply other threads:[~2014-11-05 16:51 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 15:52 [RFC][PATCH 00/12 v3] seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
2014-11-04 15:52 ` [RFC][PATCH 01/12 v3] x86/kvm/tracing: Use helper function trace_seq_buffer_ptr() Steven Rostedt
2014-11-04 16:27 ` Paolo Bonzini
2014-11-04 17:17 ` Rustad, Mark D
2014-11-04 19:09 ` Steven Rostedt
2014-11-04 19:35 ` Steven Rostedt
2014-11-04 20:09 ` Rustad, Mark D
2014-11-05 10:28 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 02/12 v3] RAS/tracing: Use trace_seq_buffer_ptr() helper instead of open coded Steven Rostedt
2014-11-04 19:59 ` Borislav Petkov
2014-11-05 10:29 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 03/12 v3] tracing: Create seq_buf layer in trace_seq Steven Rostedt
2014-11-05 14:22 ` Petr Mladek
2014-11-05 18:41 ` Steven Rostedt
2014-11-05 20:00 ` Steven Rostedt
2014-11-05 21:17 ` Steven Rostedt
2014-11-05 21:21 ` Steven Rostedt
2014-11-06 16:33 ` Petr Mladek
2014-11-07 18:30 ` Steven Rostedt
2014-11-07 18:59 ` Joe Perches
2014-11-07 19:10 ` Steven Rostedt
2014-11-10 13:53 ` Petr Mladek
2014-11-10 17:37 ` Steven Rostedt
2014-11-10 19:02 ` Petr Mladek
2014-11-06 16:13 ` Petr Mladek
2014-11-05 14:26 ` Petr Mladek
2014-11-05 18:42 ` Steven Rostedt
2014-11-04 15:52 ` [RFC][PATCH 04/12 v3] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
2014-11-05 14:45 ` Petr Mladek
2014-11-05 20:10 ` Steven Rostedt
2014-11-06 14:18 ` Petr Mladek
2014-11-06 21:09 ` Steven Rostedt
2014-11-06 15:01 ` Petr Mladek
2014-11-07 18:34 ` Steven Rostedt
2014-11-10 14:03 ` Petr Mladek
2014-11-10 17:38 ` Steven Rostedt
2014-11-04 15:52 ` [RFC][PATCH 05/12 v3] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
2014-11-05 15:57 ` Petr Mladek
2014-11-05 20:14 ` Steven Rostedt
2014-11-06 14:24 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 06/12 v3] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
2014-11-05 16:00 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 07/12 v3] tracing: Have seq_buf use full buffer Steven Rostedt
2014-11-05 16:31 ` Petr Mladek
2014-11-05 20:21 ` Steven Rostedt
2014-11-05 21:06 ` Steven Rostedt
2014-11-06 15:31 ` Petr Mladek
2014-11-06 19:24 ` Steven Rostedt
2014-11-07 9:11 ` Petr Mladek
2014-11-07 18:37 ` Steven Rostedt
2014-11-10 18:11 ` Petr Mladek
2014-11-06 15:13 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 08/12 v3] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
2014-11-05 16:51 ` Petr Mladek [this message]
2014-11-05 20:26 ` Steven Rostedt
2014-11-07 18:39 ` Steven Rostedt
2014-11-10 18:33 ` Petr Mladek
2014-11-10 19:23 ` Steven Rostedt
2014-11-04 15:52 ` [RFC][PATCH 09/12 v3] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
2014-11-05 16:57 ` Petr Mladek
2014-11-05 20:32 ` Steven Rostedt
2014-11-04 15:52 ` [RFC][PATCH 10/12 v3] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
2014-11-05 17:06 ` Petr Mladek
2014-11-05 20:33 ` Steven Rostedt
2014-11-05 20:42 ` Steven Rostedt
2014-11-06 14:39 ` Petr Mladek
2014-11-07 20:36 ` Junio C Hamano
2014-11-07 21:49 ` Steven Rostedt
2014-11-10 18:43 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 11/12 v3] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
2014-11-06 16:56 ` Petr Mladek
2014-11-04 15:52 ` [RFC][PATCH 12/12 v3] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
2014-11-04 23:05 ` Jiri Kosina
2014-11-04 23:41 ` Steven Rostedt
2014-11-06 18:41 ` Petr Mladek
2014-11-07 18:56 ` Steven Rostedt
2014-11-10 18:58 ` Petr Mladek
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