[PATCH v4 08/10] coresight: tmc-etf: Remove sharing guards from ETF

[James Clark <james.clark@linaro.org>]

Potential sink sharing is now identified during AUX setup. Trust the
core sharing rules when enabling an event and use the sink reference
count to avoid reconfiguring hardware that is already active.

Remove the redundant PID tracking from ETF and the TMC driver state.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 drivers/hwtracing/coresight/coresight-tmc-core.c |  2 --
 drivers/hwtracing/coresight/coresight-tmc-etf.c  | 22 ++--------------------
 drivers/hwtracing/coresight/coresight-tmc.h      |  4 ----
 3 files changed, 2 insertions(+), 26 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 864da1eea52c..e3c94dca1152 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -800,8 +800,6 @@ static int __tmc_probe(struct device *dev, struct resource *res)
 	devid = readl_relaxed(drvdata->base + CORESIGHT_DEVID);
 	drvdata->config_type = BMVAL(devid, 6, 7);
 	drvdata->memwidth = tmc_get_memwidth(devid);
-	/* This device is not associated with a session */
-	drvdata->pid = -1;
 	drvdata->etr_mode = ETR_MODE_AUTO;
 
 	if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 8882b1c4cdc0..e2204a47c1f6 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -250,11 +250,9 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev,
 				    struct coresight_path *path)
 {
 	int ret = 0;
-	pid_t pid;
 	unsigned long flags;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	struct perf_output_handle *handle = path->handle;
-	struct cs_buffers *buf = etm_perf_sink_config(handle);
 
 	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 	do {
@@ -270,31 +268,18 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev,
 			break;
 		}
 
-		/* Get a handle on the pid of the process to monitor */
-		pid = buf->pid;
-
-		if (drvdata->pid != -1 && drvdata->pid != pid) {
-			ret = -EBUSY;
-			break;
-		}
-
 		ret = tmc_set_etf_buffer(csdev, handle);
 		if (ret)
 			break;
 
-		/*
-		 * No HW configuration is needed if the sink is already in
-		 * use for this session.
-		 */
-		if (drvdata->pid == pid) {
+		/*  No HW configuration is needed if the sink is already in use. */
+		if (csdev->refcnt) {
 			csdev->refcnt++;
 			break;
 		}
 
 		ret  = tmc_etb_enable_hw(drvdata);
 		if (!ret) {
-			/* Associate with monitored process. */
-			drvdata->pid = pid;
 			coresight_set_mode(csdev, CS_MODE_PERF);
 			csdev->refcnt++;
 		}
@@ -351,8 +336,6 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev)
 	/* Complain if we (somehow) got out of sync */
 	WARN_ON_ONCE(coresight_get_mode(csdev) == CS_MODE_DISABLED);
 	tmc_etb_disable_hw(drvdata);
-	/* Dissociate from monitored process. */
-	drvdata->pid = -1;
 	coresight_set_mode(csdev, CS_MODE_DISABLED);
 
 	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -432,7 +415,6 @@ static void *tmc_alloc_etf_buffer(struct coresight_device *csdev,
 	if (!buf)
 		return NULL;
 
-	buf->pid = task_pid_nr(event->owner);
 	buf->snapshot = overwrite;
 	buf->nr_pages = nr_pages;
 	buf->data_pages = pages;
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index d63fa60ecce8..36b54ebf30ba 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -217,9 +217,6 @@ struct tmc_resrv_buf {
  * @crashdev:	specifics to handle "/dev/crash_tmc_xyz" entry for reading
  *		crash tracedata.
  * @spinlock:	only one at a time pls.
- * @pid:	Process ID of the process that owns the session that is using
- *		this component. For example this would be the pid of the Perf
- *		process.
  * @reading:	buffer's in the reading through "/dev/xyz.tmc" entry
  * @stop_on_flush: Stop on flush trigger user configuration.
  * @buf:	Snapshot of the trace data for ETF/ETB.
@@ -252,7 +249,6 @@ struct tmc_drvdata {
 	struct miscdevice	miscdev;
 	struct miscdevice	crashdev;
 	raw_spinlock_t		spinlock;
-	pid_t			pid;
 	bool			reading;
 	bool			stop_on_flush;
 	union {

-- 
2.43.0