spidev: BKL removal

Another step to removing ->ioctl and to removing the BKL

[dbrownell@users.sourceforge.net: take final step; BKL not needed]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 2833fd772a24feb160f33a07e4bbbcc23a5cbb21..e5e0cfed5e3b3fedff7f81983a73f4b94a9de8ca 100644 (file)
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -228,7 +228,6 @@ static int spidev_message(struct spidev_data *spidev,
         * We walk the array of user-provided transfers, using each one
         * to initialize a kernel version of the same transfer.
         */
-       mutex_lock(&spidev->buf_lock);
        buf = spidev->buffer;
        total = 0;
        for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
@@ -296,14 +295,12 @@ static int spidev_message(struct spidev_data *spidev,
        status = total;
 
 done:
-       mutex_unlock(&spidev->buf_lock);
        kfree(k_xfers);
        return status;
 }
 
-static int
-spidev_ioctl(struct inode *inode, struct file *filp,
-               unsigned int cmd, unsigned long arg)
+static long
+spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
        int                     err = 0;
        int                     retval = 0;
@@ -341,6 +338,14 @@ spidev_ioctl(struct inode *inode, struct file *filp,
        if (spi == NULL)
                return -ESHUTDOWN;
 
+       /* 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:
@@ -456,6 +461,8 @@ spidev_ioctl(struct inode *inode, struct file *filp,
                kfree(ioc);
                break;
        }
+
+       mutex_unlock(&spidev->buf_lock);
        spi_dev_put(spi);
        return retval;
 }
@@ -533,7 +540,7 @@ static struct file_operations spidev_fops = {
         */
        .write =        spidev_write,
        .read =         spidev_read,
-       .ioctl =        spidev_ioctl,
+       .unlocked_ioctl = spidev_ioctl,
        .open =         spidev_open,
        .release =      spidev_release,
 };