linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, tamas.zsoldos@arm.com,
	al.grant@arm.com, leo.yan@linaro.org, mike.leach@linaro.org,
	mathieu.poirier@linaro.org, suzuki.poulose@arm.com,
	anshuman.khandual@arm.com, jinlmao@qti.qualcomm.com
Subject: [PATCH v2 03/10] coresight: etm-pmu: Ensure the AUX handle is valid
Date: Fri, 23 Jul 2021 13:46:04 +0100	[thread overview]
Message-ID: <20210723124611.3828908-4-suzuki.poulose@arm.com> (raw)
In-Reply-To: <20210723124611.3828908-1-suzuki.poulose@arm.com>

The ETM perf infrastructure closes out a handle during event_stop
or on an error in starting the event. In either case, it is possible
for a "sink" to update/close the handle, under certain circumstances.
(e.g no space in ring buffer.). So, ensure that we handle this
gracefully in the PMU driver by verifying the handle is still valid.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 .../hwtracing/coresight/coresight-etm-perf.c  | 27 ++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index 6f398377fec9..a6ab603afee4 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -450,8 +450,15 @@ static void etm_event_start(struct perf_event *event, int flags)
 fail_disable_path:
 	coresight_disable_path(path);
 fail_end_stop:
-	perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
-	perf_aux_output_end(handle, 0);
+	/*
+	 * Check if the handle is still associated with the event,
+	 * to handle cases where if the sink failed to start the
+	 * trace and TRUNCATED the handle already.
+	 */
+	if (READ_ONCE(handle->event)) {
+		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
+		perf_aux_output_end(handle, 0);
+	}
 fail:
 	event->hw.state = PERF_HES_STOPPED;
 	goto out;
@@ -519,7 +526,21 @@ static void etm_event_stop(struct perf_event *event, int mode)
 
 		size = sink_ops(sink)->update_buffer(sink, handle,
 					      event_data->snk_config);
-		perf_aux_output_end(handle, size);
+		/*
+		 * Make sure the handle is still valid as the
+		 * sink could have closed it from an IRQ.
+		 * The sink driver must handle the race with
+		 * update_buffer() and IRQ. Thus either we
+		 * should get a valid handle and valid size
+		 * (which may be 0).
+		 *
+		 * But we should never get a non-zero size with
+		 * an invalid handle.
+		 */
+		if (READ_ONCE(handle->event))
+			perf_aux_output_end(handle, size);
+		else
+			WARN_ON(size);
 	}
 
 	/* Disabling the path make its elements available to other sessions */
-- 
2.24.1


  parent reply	other threads:[~2021-07-23 12:46 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 12:46 [PATCH v2 00/10] coresight: TRBE and Self-Hosted trace fixes Suzuki K Poulose
2021-07-23 12:46 ` [PATCH v2 01/10] coresight: etm4x: Save restore TRFCR_EL1 Suzuki K Poulose
2021-07-30  3:05   ` Anshuman Khandual
2021-07-23 12:46 ` [PATCH v2 02/10] coresight: etm4x: Use Trace Filtering controls dynamically Suzuki K Poulose
2021-07-30  3:48   ` Anshuman Khandual
2021-07-30 11:29     ` Suzuki K Poulose
2021-07-23 12:46 ` Suzuki K Poulose [this message]
2021-07-30  4:14   ` [PATCH v2 03/10] coresight: etm-pmu: Ensure the AUX handle is valid Anshuman Khandual
2021-07-23 12:46 ` [PATCH v2 04/10] coresight: trbe: Ensure the format flag is set on truncation Suzuki K Poulose
2021-07-30  4:26   ` Anshuman Khandual
2021-07-30 11:37     ` Suzuki K Poulose
2021-07-23 12:46 ` [PATCH v2 05/10] coresight: trbe: Drop duplicate TRUNCATE flags Suzuki K Poulose
2021-07-30  4:47   ` Anshuman Khandual
2021-07-30 12:58     ` Suzuki K Poulose
2021-07-23 12:46 ` [PATCH v2 06/10] coresight: trbe: Fix handling of spurious interrupts Suzuki K Poulose
2021-07-30  5:15   ` Anshuman Khandual
2021-07-30 12:57     ` Suzuki K Poulose
2021-07-23 12:46 ` [PATCH v2 07/10] coresight: trbe: Do not truncate buffer on IRQ Suzuki K Poulose
2021-07-26 12:34   ` Mike Leach
2021-07-26 16:01     ` Suzuki K Poulose
2021-07-27 10:46       ` Mike Leach
2021-07-27 13:06         ` Suzuki K Poulose
2021-07-28  9:25           ` Suzuki K Poulose
2021-07-23 12:46 ` [PATCH v2 08/10] coresight: trbe: Unify the enabling sequence Suzuki K Poulose
2021-07-30  5:40   ` Anshuman Khandual
2021-07-23 12:46 ` [PATCH v2 09/10] coresight: trbe: End the AUX handle on truncation Suzuki K Poulose
2021-07-30  5:54   ` Anshuman Khandual
2021-07-23 12:46 ` [PATCH v2 10/10] coresight: trbe: Prohibit trace before disabling TRBE Suzuki K Poulose
2021-07-30  6:58   ` Anshuman Khandual
2021-07-23 13:45 ` [PATCH v2 00/10] coresight: TRBE and Self-Hosted trace fixes Suzuki K Poulose

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=20210723124611.3828908-4-suzuki.poulose@arm.com \
    --to=suzuki.poulose@arm.com \
    --cc=al.grant@arm.com \
    --cc=anshuman.khandual@arm.com \
    --cc=coresight@lists.linaro.org \
    --cc=jinlmao@qti.qualcomm.com \
    --cc=leo.yan@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mathieu.poirier@linaro.org \
    --cc=mike.leach@linaro.org \
    --cc=tamas.zsoldos@arm.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).