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 04/12 v3] tracing: Convert seq_buf_path() to be like seq_path()
Date: Thu, 6 Nov 2014 15:18:22 +0100 [thread overview]
Message-ID: <20141106141820.GC2001@dhcp128.suse.cz> (raw)
In-Reply-To: <20141105151053.744b77f2@gandalf.local.home>
On Wed 2014-11-05 15:10:53, Steven Rostedt wrote:
> On Wed, 5 Nov 2014 15:45:53 +0100
> Petr Mladek <pmladek@suse.cz> wrote:
>
>
> > > */
> > > -int seq_buf_path(struct seq_buf *s, const struct path *path)
> > > +int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
> > > {
> > > - unsigned int len = SEQ_BUF_LEFT(s);
> > > - unsigned char *p;
> > > -
> > > - WARN_ON(s->size == 0);
> >
> > I would keep this check.
>
> Yeah, I could.
great :-)
> >
> > > - p = d_path(path, s->buffer + s->len, len);
> > > - if (!IS_ERR(p)) {
> > > - p = mangle_path(s->buffer + s->len, p, "\n");
> > > - if (p) {
> > > - s->len = p - s->buffer;
> > > - return 0;
> > > + char *buf = s->buffer + s->len;
> > > + size_t size = SEQ_BUF_LEFT(s);
> >
> > I would use the variable name "len" to make it consistent with
> > the other fucntions in seq_buf.c.
>
> Note, seq_path() is a different beast than the other seq_*() functions
> (this will be keeping a return code). And the inconsistency is in
> seq_file.c as well. I'm not saying we shouldn't keep it consistent. But
> as this patch is to make seq_buf like seq_file, I'll keep the
> inconsistencies the same too.
Ah, I have missed this.
> We can always do a clean up later.
Fair enough. The result of this patch set (safe printing of
backtraces from all CPUs) is more important than this clean up.
[...]
> >
> > > - return -1;
> > > + if (res > 0)
> > > + s->len += res;
> > > +
> > > + return res;
> >
> > It returns -1 on failure and the number of written characters on
> > success. This is incompatible with the other seq_buf functions
> > and with the comment above this function. Also it changes the
> > return value from trace_seq_path().
> >
> > I do not mind about the used scheme but I think that we should
> > make it consistent.
> >
>
> As seq_file has had this inconsistency for a long time, and this code
> is to try to merge the code between trace_seq and seq_file, I'm going
> to follow seq_file as that has been around much longer than trace_seq.
I see. Well, we still need to fix trace_seq_path() or its callers.
For example, seq_print_user_ip() checks trace_seq_path() return value
and expects 0 on failure.
Best Regards,
Petr
next prev parent reply other threads:[~2014-11-06 14:18 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 [this message]
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
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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