diff options
Diffstat (limited to 'drivers/hwtracing/coresight/coresight-tmc-etr.c')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-tmc-etr.c | 38 |
1 files changed, 33 insertions, 5 deletions
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index 8c75800003d2..df6e4b0b84e9 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1474,6 +1474,13 @@ tmc_update_etr_buffer(struct coresight_device *csdev, struct etr_buf *etr_buf = etr_perf->etr_buf; spin_lock_irqsave(&drvdata->spinlock, flags); + + /* Don't do anything if another tracer is using this sink */ + if (atomic_read(csdev->refcnt) != 1) { + spin_unlock_irqrestore(&drvdata->spinlock, flags); + goto out; + } + if (WARN_ON(drvdata->perf_data != etr_perf)) { lost = true; spin_unlock_irqrestore(&drvdata->spinlock, flags); @@ -1513,17 +1520,15 @@ out: static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data) { int rc = 0; + pid_t pid; unsigned long flags; struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); struct perf_output_handle *handle = data; struct etr_perf_buffer *etr_perf = etm_perf_sink_config(handle); spin_lock_irqsave(&drvdata->spinlock, flags); - /* - * There can be only one writer per sink in perf mode. If the sink - * is already open in SYSFS mode, we can't use it. - */ - if (drvdata->mode != CS_MODE_DISABLED || WARN_ON(drvdata->perf_data)) { + /* Don't use this sink if it is already claimed by sysFS */ + if (drvdata->mode == CS_MODE_SYSFS) { rc = -EBUSY; goto unlock_out; } @@ -1533,10 +1538,31 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data) goto unlock_out; } + /* Get a handle on the pid of the process to monitor */ + pid = etr_perf->pid; + + /* Do not proceed if this device is associated with another session */ + if (drvdata->pid != -1 && drvdata->pid != pid) { + rc = -EBUSY; + goto unlock_out; + } + etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf); drvdata->perf_data = etr_perf; + + /* + * No HW configuration is needed if the sink is already in + * use for this session. + */ + if (drvdata->pid == pid) { + atomic_inc(csdev->refcnt); + goto unlock_out; + } + rc = tmc_etr_enable_hw(drvdata, etr_perf->etr_buf); if (!rc) { + /* Associate with monitored process. */ + drvdata->pid = pid; drvdata->mode = CS_MODE_PERF; atomic_inc(csdev->refcnt); } @@ -1580,6 +1606,8 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev) /* Complain if we (somehow) got out of sync */ WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED); tmc_etr_disable_hw(drvdata); + /* Dissociate from monitored process. */ + drvdata->pid = -1; drvdata->mode = CS_MODE_DISABLED; spin_unlock_irqrestore(&drvdata->spinlock, flags); |