Merge tag 'spi-fix-v7.0-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi

Pull spi fixes from Mark Brown:
 "There's a relatively large but ultimately simple fix for spidev here
  which addresses some ABBA races by simplifying down to just using a
  single lock, it's not clear to me that there was ever any benefit in
  having the two separate locks in the first place.

  We also have simple missing error check fix in in the wpcm-fiu driver"

* tag 'spi-fix-v7.0-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: spidev: fix lock inversion between spi_lock and buf_lock
  spi: wpcm-fiu: Fix potential NULL pointer dereference in wpcm_fiu_probe()

Author: torvalds

drivers/spi/spi-wpcm-fiu.c

@@ -459,11 +459,11 @@ static int wpcm_fiu_probe(struct platform_device *pdev)
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "memory");
 	fiu->memory = devm_ioremap_resource(dev, res);
-	fiu->memory_size = min_t(size_t, resource_size(res), MAX_MEMORY_SIZE_TOTAL);
 	if (IS_ERR(fiu->memory))
 		return dev_err_probe(dev, PTR_ERR(fiu->memory),
 			       "Failed to map flash memory window\n");
 
+	fiu->memory_size = min_t(size_t, resource_size(res), MAX_MEMORY_SIZE_TOTAL);
 	fiu->shm_regmap = syscon_regmap_lookup_by_phandle_optional(dev->of_node, "nuvoton,shm");
 
 	wpcm_fiu_hw_init(fiu);

drivers/spi/spidev.c

@@ -74,7 +74,6 @@ struct spidev_data {
 	struct list_head	device_entry;
 
 	/* TX/RX buffers are NULL unless this device is open (users > 0) */
-	struct mutex		buf_lock;
 	unsigned		users;
 	u8			*tx_buffer;
 	u8			*rx_buffer;
@@ -102,24 +101,6 @@ spidev_sync_unlocked(struct spi_device *spi, struct spi_message *message)
 	return status;
 }
 
-static ssize_t
-spidev_sync(struct spidev_data *spidev, struct spi_message *message)
-{
-	ssize_t status;
-	struct spi_device *spi;
-
-	mutex_lock(&spidev->spi_lock);
-	spi = spidev->spi;
-
-	if (spi == NULL)
-		status = -ESHUTDOWN;
-	else
-		status = spidev_sync_unlocked(spi, message);
-
-	mutex_unlock(&spidev->spi_lock);
-	return status;
-}
-
 static inline ssize_t
 spidev_sync_write(struct spidev_data *spidev, size_t len)
 {
@@ -132,7 +113,8 @@ spidev_sync_write(struct spidev_data *spidev, size_t len)
 
 	spi_message_init(&m);
 	spi_message_add_tail(&t, &m);
-	return spidev_sync(spidev, &m);
+
+	return spidev_sync_unlocked(spidev->spi, &m);
 }
 
 static inline ssize_t
@@ -147,7 +129,8 @@ spidev_sync_read(struct spidev_data *spidev, size_t len)
 
 	spi_message_init(&m);
 	spi_message_add_tail(&t, &m);
-	return spidev_sync(spidev, &m);
+
+	return spidev_sync_unlocked(spidev->spi, &m);
 }
 
 /*-------------------------------------------------------------------------*/
@@ -157,15 +140,19 @@ static ssize_t
 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 {
 	struct spidev_data	*spidev;
-	ssize_t			status;
+	ssize_t			status = -ESHUTDOWN;
 
 	/* chipselect only toggles at start or end of operation */
 	if (count > bufsiz)
 		return -EMSGSIZE;
 
 	spidev = filp->private_data;
 
-	mutex_lock(&spidev->buf_lock);
+	mutex_lock(&spidev->spi_lock);
+
+	if (spidev->spi == NULL)
+		goto err_spi_removed;
+
 	status = spidev_sync_read(spidev, count);
 	if (status > 0) {
 		unsigned long	missing;
@@ -176,7 +163,9 @@ spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 		else
 			status = status - missing;
 	}
-	mutex_unlock(&spidev->buf_lock);
+
+err_spi_removed:
+	mutex_unlock(&spidev->spi_lock);
 
 	return status;
 }
@@ -187,7 +176,7 @@ spidev_write(struct file *filp, const char __user *buf,
 		size_t count, loff_t *f_pos)
 {
 	struct spidev_data	*spidev;
-	ssize_t			status;
+	ssize_t			status = -ESHUTDOWN;
 	unsigned long		missing;
 
 	/* chipselect only toggles at start or end of operation */
@@ -196,13 +185,19 @@ spidev_write(struct file *filp, const char __user *buf,
 
 	spidev = filp->private_data;
 
-	mutex_lock(&spidev->buf_lock);
+	mutex_lock(&spidev->spi_lock);
+
+	if (spidev->spi == NULL)
+		goto err_spi_removed;
+
 	missing = copy_from_user(spidev->tx_buffer, buf, count);
 	if (missing == 0)
 		status = spidev_sync_write(spidev, count);
 	else
 		status = -EFAULT;
-	mutex_unlock(&spidev->buf_lock);
+
+err_spi_removed:
+	mutex_unlock(&spidev->spi_lock);
 
 	return status;
 }
@@ -379,14 +374,6 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 	ctlr = spi->controller;
 
-	/* use the buffer lock here for triple duty:
-	 *  - prevent I/O (from us) so calling spi_setup() is safe;
-	 *  - prevent concurrent SPI_IOC_WR_* from morphing
-	 *    data fields while SPI_IOC_RD_* reads them;
-	 *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
-	 */
-	mutex_lock(&spidev->buf_lock);
-
 	switch (cmd) {
 	/* read requests */
 	case SPI_IOC_RD_MODE:
@@ -510,7 +497,6 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		break;
 	}
 
-	mutex_unlock(&spidev->buf_lock);
 	spi_dev_put(spi);
 	mutex_unlock(&spidev->spi_lock);
 	return retval;
@@ -541,9 +527,6 @@ spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 		return -ESHUTDOWN;
 	}
 
-	/* SPI_IOC_MESSAGE needs the buffer locked "normally" */
-	mutex_lock(&spidev->buf_lock);
-
 	/* Check message and copy into scratch area */
 	ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 	if (IS_ERR(ioc)) {
@@ -564,7 +547,6 @@ spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 	kfree(ioc);
 
 done:
-	mutex_unlock(&spidev->buf_lock);
 	spi_dev_put(spi);
 	mutex_unlock(&spidev->spi_lock);
 	return retval;
@@ -802,7 +784,6 @@ static int spidev_probe(struct spi_device *spi)
 	/* Initialize the driver data */
 	spidev->spi = spi;
 	mutex_init(&spidev->spi_lock);
-	mutex_init(&spidev->buf_lock);
 
 	INIT_LIST_HEAD(&spidev->device_entry);