linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: "Leo Yan" <leo.yan@linaro.org>,
	"Arnaldo Carvalho de Melo" <acme@kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
	"Jiri Olsa" <jolsa@redhat.com>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Mathieu Poirier" <mathieu.poirier@linaro.org>,
	"Mike Leach" <mike.leach@linaro.org>,
	"Michael Petlan" <mpetlan@redhat.com>,
	"Frank Ch. Eigler" <fche@redhat.com>,
	"Song Liu" <songliubraving@fb.com>,
	x86@kernel.org, "Daniel Díaz" <daniel.diaz@linaro.org>,
	"Andrii Nakryiko" <andriin@fb.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Sedat Dilek" <sedat.dilek@gmail.com>,
	"Andi Kleen" <ak@linux.intel.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	coresight@lists.linaro.org
Subject: Re: [PATCH v5 3/9] coresight: tmc-etf: Add comment for store ordering
Date: Tue, 14 Sep 2021 09:24:18 +0100	[thread overview]
Message-ID: <60c20d8e-4386-5c54-4607-d9399713d2ef@arm.com> (raw)
In-Reply-To: <20210809111407.596077-4-leo.yan@linaro.org>

On 09/08/2021 12:14, Leo Yan wrote:
> Since the function CS_LOCK() has contained memory barrier mb(), it
> ensures the visibility of the AUX trace data before updating the
> aux_head, thus it's needless to add any explicit barrier anymore.
> 
> Add comment to make clear for the barrier usage for ETF.
> 
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>   drivers/hwtracing/coresight/coresight-tmc-etf.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index cd0fb7bfba68..8debd4f40f06 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -553,6 +553,11 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
>   	if (buf->snapshot)
>   		handle->head += to_read;
>   
> +	/*
> +	 * CS_LOCK() contains mb() so it can ensure visibility of the AUX trace
> +	 * data before the aux_head is updated via perf_aux_output_end(), which
> +	 * is expected by the perf ring buffer.
> +	 */
>   	CS_LOCK(drvdata->base);
>   out:
>   	spin_unlock_irqrestore(&drvdata->spinlock, flags);
> 

I will queue this.

Thanks
Suzuki

  reply	other threads:[~2021-09-14  8:24 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-09 11:13 [PATCH v5 0/9] perf: Refine barriers for AUX ring buffer Leo Yan
2021-08-09 11:13 ` [PATCH v5 1/9] perf/ring_buffer: Add comment for barriers on " Leo Yan
2021-08-29 10:51   ` Leo Yan
2021-08-09 11:14 ` [PATCH v5 2/9] coresight: tmc-etr: Add barrier after updating " Leo Yan
2021-08-29 10:55   ` Leo Yan
2021-09-14  9:08     ` Suzuki K Poulose
2021-08-09 11:14 ` [PATCH v5 3/9] coresight: tmc-etf: Add comment for store ordering Leo Yan
2021-09-14  8:24   ` Suzuki K Poulose [this message]
2021-08-09 11:14 ` [PATCH v5 4/9] perf/x86: Add compiler barrier after updating BTS Leo Yan
2021-08-29 10:56   ` Leo Yan
2021-09-14  9:51     ` Peter Zijlstra
2021-09-14 10:05       ` Leo Yan
2021-09-14 11:47         ` Peter Zijlstra
2021-09-17 15:10   ` [tip: perf/core] " tip-bot2 for Leo Yan
2021-08-09 11:14 ` [PATCH v5 5/9] perf auxtrace: Use WRITE_ONCE() for updating aux_tail Leo Yan
2021-08-09 19:59   ` Arnaldo Carvalho de Melo
2021-08-09 11:14 ` [PATCH v5 6/9] perf auxtrace: Drop legacy __sync functions Leo Yan
2021-08-09 20:00   ` Arnaldo Carvalho de Melo
2021-08-09 11:14 ` [PATCH v5 7/9] perf auxtrace: Remove auxtrace_mmap__read_snapshot_head() Leo Yan
2021-08-09 20:01   ` Arnaldo Carvalho de Melo
2021-08-09 11:14 ` [PATCH v5 8/9] perf: Cleanup for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT Leo Yan
2021-08-09 20:02   ` Arnaldo Carvalho de Melo
2021-08-09 11:14 ` [PATCH v5 9/9] tools: Remove feature-sync-compare-and-swap feature detection Leo Yan
2021-08-09 20:02   ` Arnaldo Carvalho de Melo

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=60c20d8e-4386-5c54-4607-d9399713d2ef@arm.com \
    --to=suzuki.poulose@arm.com \
    --cc=acme@kernel.org \
    --cc=adrian.hunter@intel.com \
    --cc=ak@linux.intel.com \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=andriin@fb.com \
    --cc=ast@kernel.org \
    --cc=bp@alien8.de \
    --cc=coresight@lists.linaro.org \
    --cc=daniel.diaz@linaro.org \
    --cc=fche@redhat.com \
    --cc=hpa@zytor.com \
    --cc=jolsa@redhat.com \
    --cc=leo.yan@linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-perf-users@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mathieu.poirier@linaro.org \
    --cc=mike.leach@linaro.org \
    --cc=mingo@redhat.com \
    --cc=mpetlan@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=sedat.dilek@gmail.com \
    --cc=songliubraving@fb.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /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).