static int tmc_enable_etf_sink_sysfs()

in coresight/coresight-tmc-etf.c [151:223]

• 42 lines of code
• 8 McCabe index (conditional complexity)

static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
{
	int ret = 0;
	bool used = false;
	char *buf = NULL;
	unsigned long flags;
	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

	/*
	 * If we don't have a buffer release the lock and allocate memory.
	 * Otherwise keep the lock and move along.
	 */
	spin_lock_irqsave(&drvdata->spinlock, flags);
	if (!drvdata->buf) {
		spin_unlock_irqrestore(&drvdata->spinlock, flags);

		/* Allocating the memory here while outside of the spinlock */
		buf = kzalloc(drvdata->size, GFP_KERNEL);
		if (!buf)
			return -ENOMEM;

		/* Let's try again */
		spin_lock_irqsave(&drvdata->spinlock, flags);
	}

	if (drvdata->reading) {
		ret = -EBUSY;
		goto out;
	}

	/*
	 * In sysFS mode we can have multiple writers per sink.  Since this
	 * sink is already enabled no memory is needed and the HW need not be
	 * touched.
	 */
	if (drvdata->mode == CS_MODE_SYSFS) {
		atomic_inc(csdev->refcnt);
		goto out;
	}

	/*
	 * If drvdata::buf isn't NULL, memory was allocated for a previous
	 * trace run but wasn't read.  If so simply zero-out the memory.
	 * Otherwise use the memory allocated above.
	 *
	 * The memory is freed when users read the buffer using the
	 * /dev/xyz.{etf|etb} interface.  See tmc_read_unprepare_etf() for
	 * details.
	 */
	if (drvdata->buf) {
		memset(drvdata->buf, 0, drvdata->size);
	} else {
		used = true;
		drvdata->buf = buf;
	}

	ret = tmc_etb_enable_hw(drvdata);
	if (!ret) {
		drvdata->mode = CS_MODE_SYSFS;
		atomic_inc(csdev->refcnt);
	} else {
		/* Free up the buffer if we failed to enable */
		used = false;
	}
out:
	spin_unlock_irqrestore(&drvdata->spinlock, flags);

	/* Free memory outside the spinlock if need be */
	if (!used)
		kfree(buf);

	return ret;
}