From: Tom Zanussi <zanussi@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org,
vedang.patel@intel.com, bigeasy@linutronix.de,
joel@joelfernandes.org, mathieu.desnoyers@efficios.com,
julia@ni.com, linux-kernel@vger.kernel.org,
linux-rt-users@vger.kernel.org
Subject: Re: [PATCH v15 05/15] tracing: Add conditional snapshot
Date: Thu, 14 Feb 2019 17:25:11 -0600 [thread overview]
Message-ID: <1550186711.2498.10.camel@kernel.org> (raw)
In-Reply-To: <20190214181150.0453ecdf@gandalf.local.home>
Hi Steve,
On Thu, 2019-02-14 at 18:11 -0500, Steven Rostedt wrote:
> On Wed, 13 Feb 2019 17:42:45 -0600
> Tom Zanussi <zanussi@kernel.org> wrote:
>
> > +
> > +/**
> > + * tracing_snapshot_cond_enable - enable conditional snapshot for
> > an instance
> > + * @tr: The tracing instance
> > + * @cond_data: User data to associate with the snapshot
> > + * @update: Implementation of the cond_snapshot update
> > function
> > + *
> > + * Check whether the conditional snapshot for the given instance
> > has
> > + * already been enabled, or if the current tracer is already using
> > a
> > + * snapshot; if so, return -EBUSY, else create a cond_snapshot and
> > + * save the cond_data and update function inside.
> > + *
> > + * Returns 0 if successful, error otherwise.
> > + */
> > +int tracing_snapshot_cond_enable(struct trace_array *tr, void
> > *cond_data,
> > + cond_update_fn_t update)
> > +{
> > + struct cond_snapshot *cond_snapshot;
> > + int ret = 0;
> > +
> > + cond_snapshot = kzalloc(sizeof(*cond_snapshot),
> > GFP_KERNEL);
> > + if (!cond_snapshot)
> > + return -ENOMEM;
> > +
> > + cond_snapshot->cond_data = cond_data;
> > + cond_snapshot->update = update;
> > +
> > + mutex_lock(&trace_types_lock);
> > +
> > + ret = tracing_alloc_snapshot_instance(tr);
> > + if (ret)
> > + goto fail_unlock;
> > +
> > + if (tr->current_trace->use_max_tr) {
> > + ret = -EBUSY;
> > + goto fail_unlock;
> > + }
> > +
> > + if (tr->cond_snapshot) {
> > + ret = -EBUSY;
> > + goto fail_unlock;
> > + }
> > +
> > + arch_spin_lock(&tr->max_lock);
> > + tr->cond_snapshot = cond_snapshot;
> > + arch_spin_unlock(&tr->max_lock);
> > +
> > + mutex_unlock(&trace_types_lock);
> > +
> > + return ret;
> > +
> > + fail_unlock:
> > + mutex_unlock(&trace_types_lock);
> > + kfree(cond_snapshot);
> > + return ret;
>
> Some whitespace damage here. No need to resend, I fixed it.
>
OK, thanks.
>
> > +}
> > +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable);
> > +
>
> I also added this change on top of your series.
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 0460cc0f28fd..2cf3c747a357 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1116,6 +1116,14 @@ int tracing_snapshot_cond_enable(struct
> trace_array *tr, void *cond_data,
> goto fail_unlock;
> }
>
> + /*
> + * The cond_snapshot can only change to NULL without the
> + * trace_types_lock. We don't care if we race with it going
> + * to NULL, but we want to make sure that it's not set to
> + * something other than NULL when we get here, which we can
> + * do safely with only holding the trace_types_lock and not
> + * having to take the max_lock.
> + */
> if (tr->cond_snapshot) {
> ret = -EBUSY;
> goto fail_unlock;
>
Looks good, thanks for adding that back.
Tom
> I'll start testing your series now.
>
> Thanks!
>
> -- Steve
>
next prev parent reply other threads:[~2019-02-14 23:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 23:42 [PATCH v15 00/15] tracing: Hist trigger snapshot and onchange additions Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 01/15] tracing: Refactor hist trigger action code Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 02/15] tracing: Make hist trigger Documentation better reflect actions/handlers Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 03/15] tracing: Split up onmatch action data Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 04/15] tracing: Generalize hist trigger onmax and save action Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 05/15] tracing: Add conditional snapshot Tom Zanussi
2019-02-14 23:11 ` Steven Rostedt
2019-02-14 23:25 ` Tom Zanussi [this message]
2019-02-13 23:42 ` [PATCH v15 06/15] tracing: Add hist trigger snapshot() action Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 07/15] tracing: Add hist trigger snapshot() action Documentation Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 08/15] tracing: Add hist trigger onchange() handler Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 09/15] tracing: Add hist trigger onchange() handler Documentation Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 10/15] tracing: Add alternative synthetic event trace action syntax Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 11/15] tracing: Add SPDX license GPL-2.0 license identifier to inter-event testcases Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 12/15] tracing: Add hist trigger snapshot() action test case Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 13/15] tracing: Add hist trigger onchange() handler " Tom Zanussi
2019-02-13 23:42 ` [PATCH v15 14/15] tracing: Add alternative synthetic event trace action " Tom Zanussi
2019-02-15 15:06 ` Masami Hiramatsu
2019-02-13 23:42 ` [PATCH v15 15/15] tracing: Add hist trigger action 'expected fail' " Tom Zanussi
2019-02-15 15:08 ` Masami Hiramatsu
2019-02-15 15:36 ` Steven Rostedt
2019-02-20 17:17 ` Steven Rostedt
2019-02-20 17:38 ` Tom Zanussi
2019-02-20 17:56 ` Steven Rostedt
2019-02-20 18:10 ` Tom Zanussi
2019-02-20 18:33 ` Steven Rostedt
2019-02-20 18:45 ` Tom Zanussi
2019-02-20 18:54 ` Steven Rostedt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1550186711.2498.10.camel@kernel.org \
--to=zanussi@kernel.org \
--cc=bigeasy@linutronix.de \
--cc=joel@joelfernandes.org \
--cc=julia@ni.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=mhiramat@kernel.org \
--cc=namhyung@kernel.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=vedang.patel@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).