Merge branch 'perf/core' into perf/uprobes

Merge in latest upstream (and the latest perf development tree),
to prepare for tooling changes, and also to pick up v3.4 MM
changes that the uprobes code needs to take care of.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 73 insertions, 58 deletions

diff --git a/drivers/misc/carma/carma-fpga.c b/drivers/misc/carma/carma-fpga.c
index 14e974b2a78..8c279da0741 100644
--- a/drivers/misc/carma/carma-fpga.c
+++ b/drivers/misc/carma/carma-fpga.c
@@ -560,6 +560,9 @@ static void data_enable_interrupts(struct fpga_device *priv)
 
 	/* flush the writes */
 	fpga_read_reg(priv, 0, MMAP_REG_STATUS);
+	fpga_read_reg(priv, 1, MMAP_REG_STATUS);
+	fpga_read_reg(priv, 2, MMAP_REG_STATUS);
+	fpga_read_reg(priv, 3, MMAP_REG_STATUS);
 
 	/* switch back to the external interrupt source */
 	iowrite32be(0x3F, priv->regs + SYS_IRQ_SOURCE_CTL);
@@ -591,8 +594,12 @@ static void data_dma_cb(void *data)
 	list_move_tail(&priv->inflight->entry, &priv->used);
 	priv->inflight = NULL;
 
-	/* clear the FPGA status and re-enable interrupts */
-	data_enable_interrupts(priv);
+	/*
+	 * If data dumping is still enabled, then clear the FPGA
+	 * status registers and re-enable FPGA interrupts
+	 */
+	if (priv->enabled)
+		data_enable_interrupts(priv);
 
 	spin_unlock_irqrestore(&priv->lock, flags);
 
@@ -708,6 +715,15 @@ static irqreturn_t data_irq(int irq, void *dev_id)
 
 	spin_lock(&priv->lock);
 
+	/*
+	 * This is an error case that should never happen.
+	 *
+	 * If this driver has a bug and manages to re-enable interrupts while
+	 * a DMA is in progress, then we will hit this statement and should
+	 * start paying attention immediately.
+	 */
+	BUG_ON(priv->inflight != NULL);
+
 	/* hide the interrupt by switching the IRQ driver to GPIO */
 	data_disable_interrupts(priv);
 
@@ -762,11 +778,15 @@ out:
  */
 static int data_device_enable(struct fpga_device *priv)
 {
+	bool enabled;
 	u32 val;
 	int ret;
 
 	/* multiple enables are safe: they do nothing */
-	if (priv->enabled)
+	spin_lock_irq(&priv->lock);
+	enabled = priv->enabled;
+	spin_unlock_irq(&priv->lock);
+	if (enabled)
 		return 0;
 
 	/* check that the FPGAs are programmed */
@@ -797,6 +817,9 @@ static int data_device_enable(struct fpga_device *priv)
 		goto out_error;
 	}
 
+	/* prevent the FPGAs from generating interrupts */
+	data_disable_interrupts(priv);
+
 	/* hookup the irq handler */
 	ret = request_irq(priv->irq, data_irq, IRQF_SHARED, drv_name, priv);
 	if (ret) {
@@ -804,11 +827,13 @@ static int data_device_enable(struct fpga_device *priv)
 		goto out_error;
 	}
 
-	/* switch to the external FPGA IRQ line */
-	data_enable_interrupts(priv);
-
-	/* success, we're enabled */
+	/* allow the DMA callback to re-enable FPGA interrupts */
+	spin_lock_irq(&priv->lock);
 	priv->enabled = true;
+	spin_unlock_irq(&priv->lock);
+
+	/* allow the FPGAs to generate interrupts */
+	data_enable_interrupts(priv);
 	return 0;
 
 out_error:
@@ -834,41 +859,40 @@ out_error:
  */
 static int data_device_disable(struct fpga_device *priv)
 {
-	int ret;
+	spin_lock_irq(&priv->lock);
 
 	/* allow multiple disable */
-	if (!priv->enabled)
+	if (!priv->enabled) {
+		spin_unlock_irq(&priv->lock);
 		return 0;
+	}
+
+	/*
+	 * Mark the device disabled
+	 *
+	 * This stops DMA callbacks from re-enabling interrupts
+	 */
+	priv->enabled = false;
 
-	/* switch to the internal GPIO IRQ line */
+	/* prevent the FPGAs from generating interrupts */
 	data_disable_interrupts(priv);
 
+	/* wait until all ongoing DMA has finished */
+	while (priv->inflight != NULL) {
+		spin_unlock_irq(&priv->lock);
+		wait_event(priv->wait, priv->inflight == NULL);
+		spin_lock_irq(&priv->lock);
+	}
+
+	spin_unlock_irq(&priv->lock);
+
 	/* unhook the irq handler */
 	free_irq(priv->irq, priv);
 
-	/*
-	 * wait for all outstanding DMA to complete
-	 *
-	 * Device interrupts are disabled, therefore another buffer cannot
-	 * be marked inflight.
-	 */
-	ret = wait_event_interruptible(priv->wait, priv->inflight == NULL);
-	if (ret)
-		return ret;
-
 	/* free the correlation table */
 	sg_free_table(&priv->corl_table);
 	priv->corl_nents = 0;
 
-	/*
-	 * We are taking the spinlock not to protect priv->enabled, but instead
-	 * to make sure that there are no readers in the process of altering
-	 * the free or used lists while we are setting this flag.
-	 */
-	spin_lock_irq(&priv->lock);
-	priv->enabled = false;
-	spin_unlock_irq(&priv->lock);
-
 	/* free all buffers: the free and used lists are not being changed */
 	data_free_buffers(priv);
 	return 0;
@@ -896,15 +920,6 @@ static unsigned int list_num_entries(struct list_head *list)
 static int data_debug_show(struct seq_file *f, void *offset)
 {
 	struct fpga_device *priv = f->private;
-	int ret;
-
-	/*
-	 * Lock the mutex first, so that we get an accurate value for enable
-	 * Lock the spinlock next, to get accurate list counts
-	 */
-	ret = mutex_lock_interruptible(&priv->mutex);
-	if (ret)
-		return ret;
 
 	spin_lock_irq(&priv->lock);
 
@@ -917,7 +932,6 @@ static int data_debug_show(struct seq_file *f, void *offset)
 	seq_printf(f, "num_dropped: %d\n", priv->num_dropped);
 
 	spin_unlock_irq(&priv->lock);
-	mutex_unlock(&priv->mutex);
 	return 0;
 }
 
@@ -970,7 +984,13 @@ static ssize_t data_en_show(struct device *dev, struct device_attribute *attr,
 			    char *buf)
 {
 	struct fpga_device *priv = dev_get_drvdata(dev);
-	return snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled);
+	int ret;
+
+	spin_lock_irq(&priv->lock);
+	ret = snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled);
+	spin_unlock_irq(&priv->lock);
+
+	return ret;
 }
 
 static ssize_t data_en_set(struct device *dev, struct device_attribute *attr,
@@ -986,6 +1006,7 @@ static ssize_t data_en_set(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 	}
 
+	/* protect against concurrent enable/disable */
 	ret = mutex_lock_interruptible(&priv->mutex);
 	if (ret)
 		return ret;
@@ -1079,6 +1100,7 @@ static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count,
 	struct fpga_reader *reader = filp->private_data;
 	struct fpga_device *priv = reader->priv;
 	struct list_head *used = &priv->used;
+	bool drop_buffer = false;
 	struct data_buf *dbuf;
 	size_t avail;
 	void *data;
@@ -1166,10 +1188,12 @@ have_buffer:
 	 * One of two things has happened, the device is disabled, or the
 	 * device has been reconfigured underneath us. In either case, we
 	 * should just throw away the buffer.
+	 *
+	 * Lockdep complains if this is done under the spinlock, so we
+	 * handle it during the unlock path.
 	 */
 	if (!priv->enabled || dbuf->size != priv->bufsize) {
-		videobuf_dma_unmap(priv->dev, &dbuf->vb);
-		data_free_buffer(dbuf);
+		drop_buffer = true;
 		goto out_unlock;
 	}
 
@@ -1178,6 +1202,12 @@ have_buffer:
 
 out_unlock:
 	spin_unlock_irq(&priv->lock);
+
+	if (drop_buffer) {
+		videobuf_dma_unmap(priv->dev, &dbuf->vb);
+		data_free_buffer(dbuf);
+	}
+
 	return count;
 }
 
@@ -1410,23 +1440,8 @@ static struct platform_driver data_of_driver = {
 	},
 };
 
-/*
- * Module Init / Exit
- */
-
-static int __init data_init(void)
-{
-	return platform_driver_register(&data_of_driver);
-}
-
-static void __exit data_exit(void)
-{
-	platform_driver_unregister(&data_of_driver);
-}
+module_platform_driver(data_of_driver);
 
 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 MODULE_DESCRIPTION("CARMA DATA-FPGA Access Driver");
 MODULE_LICENSE("GPL");
-
-module_init(data_init);
-module_exit(data_exit);