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authorDavid Brownell <david-b@pacbell.net>2008-05-23 13:05:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-24 09:56:14 -0700
commit25d5cb4b0375e5864ec0ccf35e12ff1d1b5cf3f0 (patch)
tree0d83e4176f9a8178a98631097fbf839a53702d94 /drivers/spi/spidev.c
parent5c02b575780d0d785815a1e7b79a98edddee895a (diff)
downloadlinux-linaro-stable-25d5cb4b0375e5864ec0ccf35e12ff1d1b5cf3f0.tar.gz
spi: remove some spidev oops-on-rmmod paths
Somehow the spidev code forgot to include a critical mechanism: when the underlying device is removed (e.g. spi_master rmmod), open file descriptors must be prevented from issuing new I/O requests to that device. On penalty of the oopsing reported by Sebastian Siewior <bigeasy@tglx.de> ... This is a partial fix, adding handshaking between the lower level (SPI messaging) and the file operations using the spi_dev. (It also fixes an issue where reads and writes didn't return the number of bytes sent or received.) There's still a refcounting issue to be addressed (separately). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Reported-by: Sebastian Siewior <bigeasy@tglx.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi/spidev.c')
-rw-r--r--drivers/spi/spidev.c102
1 files changed, 89 insertions, 13 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index b3518ca9f04e..41620c0fb046 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -68,6 +68,7 @@ static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG];
struct spidev_data {
struct device dev;
+ spinlock_t spi_lock;
struct spi_device *spi;
struct list_head device_entry;
@@ -85,12 +86,75 @@ MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
/*-------------------------------------------------------------------------*/
+/*
+ * We can't use the standard synchronous wrappers for file I/O; we
+ * need to protect against async removal of the underlying spi_device.
+ */
+static void spidev_complete(void *arg)
+{
+ complete(arg);
+}
+
+static ssize_t
+spidev_sync(struct spidev_data *spidev, struct spi_message *message)
+{
+ DECLARE_COMPLETION_ONSTACK(done);
+ int status;
+
+ message->complete = spidev_complete;
+ message->context = &done;
+
+ spin_lock_irq(&spidev->spi_lock);
+ if (spidev->spi == NULL)
+ status = -ESHUTDOWN;
+ else
+ status = spi_async(spidev->spi, message);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (status == 0) {
+ wait_for_completion(&done);
+ status = message->status;
+ if (status == 0)
+ status = message->actual_length;
+ }
+ return status;
+}
+
+static inline ssize_t
+spidev_sync_write(struct spidev_data *spidev, size_t len)
+{
+ struct spi_transfer t = {
+ .tx_buf = spidev->buffer,
+ .len = len,
+ };
+ struct spi_message m;
+
+ spi_message_init(&m);
+ spi_message_add_tail(&t, &m);
+ return spidev_sync(spidev, &m);
+}
+
+static inline ssize_t
+spidev_sync_read(struct spidev_data *spidev, size_t len)
+{
+ struct spi_transfer t = {
+ .rx_buf = spidev->buffer,
+ .len = len,
+ };
+ struct spi_message m;
+
+ spi_message_init(&m);
+ spi_message_add_tail(&t, &m);
+ return spidev_sync(spidev, &m);
+}
+
+/*-------------------------------------------------------------------------*/
+
/* Read-only message with current device setup */
static ssize_t
spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
struct spidev_data *spidev;
- struct spi_device *spi;
ssize_t status = 0;
/* chipselect only toggles at start or end of operation */
@@ -98,10 +162,9 @@ spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
return -EMSGSIZE;
spidev = filp->private_data;
- spi = spidev->spi;
mutex_lock(&spidev->buf_lock);
- status = spi_read(spi, spidev->buffer, count);
+ status = spidev_sync_read(spidev, count);
if (status == 0) {
unsigned long missing;
@@ -122,7 +185,6 @@ spidev_write(struct file *filp, const char __user *buf,
size_t count, loff_t *f_pos)
{
struct spidev_data *spidev;
- struct spi_device *spi;
ssize_t status = 0;
unsigned long missing;
@@ -131,12 +193,11 @@ spidev_write(struct file *filp, const char __user *buf,
return -EMSGSIZE;
spidev = filp->private_data;
- spi = spidev->spi;
mutex_lock(&spidev->buf_lock);
missing = copy_from_user(spidev->buffer, buf, count);
if (missing == 0) {
- status = spi_write(spi, spidev->buffer, count);
+ status = spidev_sync_write(spidev, count);
if (status == 0)
status = count;
} else
@@ -153,7 +214,6 @@ static int spidev_message(struct spidev_data *spidev,
struct spi_transfer *k_xfers;
struct spi_transfer *k_tmp;
struct spi_ioc_transfer *u_tmp;
- struct spi_device *spi = spidev->spi;
unsigned n, total;
u8 *buf;
int status = -EFAULT;
@@ -215,7 +275,7 @@ static int spidev_message(struct spidev_data *spidev,
spi_message_add_tail(k_tmp, &msg);
}
- status = spi_sync(spi, &msg);
+ status = spidev_sync(spidev, &msg);
if (status < 0)
goto done;
@@ -269,8 +329,16 @@ spidev_ioctl(struct inode *inode, struct file *filp,
if (err)
return -EFAULT;
+ /* guard against device removal before, or while,
+ * we issue this ioctl.
+ */
spidev = filp->private_data;
- spi = spidev->spi;
+ spin_lock_irq(&spidev->spi_lock);
+ spi = spi_dev_get(spidev->spi);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (spi == NULL)
+ return -ESHUTDOWN;
switch (cmd) {
/* read requests */
@@ -356,8 +424,10 @@ spidev_ioctl(struct inode *inode, struct file *filp,
default:
/* segmented and/or full-duplex I/O request */
if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
- || _IOC_DIR(cmd) != _IOC_WRITE)
- return -ENOTTY;
+ || _IOC_DIR(cmd) != _IOC_WRITE) {
+ retval = -ENOTTY;
+ break;
+ }
tmp = _IOC_SIZE(cmd);
if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
@@ -385,6 +455,7 @@ spidev_ioctl(struct inode *inode, struct file *filp,
kfree(ioc);
break;
}
+ spi_dev_put(spi);
return retval;
}
@@ -488,6 +559,7 @@ static int spidev_probe(struct spi_device *spi)
/* Initialize the driver data */
spidev->spi = spi;
+ spin_lock_init(&spidev->spi_lock);
mutex_init(&spidev->buf_lock);
INIT_LIST_HEAD(&spidev->device_entry);
@@ -526,13 +598,17 @@ static int spidev_remove(struct spi_device *spi)
{
struct spidev_data *spidev = dev_get_drvdata(&spi->dev);
- mutex_lock(&device_list_lock);
+ /* make sure ops on existing fds can abort cleanly */
+ spin_lock_irq(&spidev->spi_lock);
+ spidev->spi = NULL;
+ spin_unlock_irq(&spidev->spi_lock);
+ /* prevent new opens */
+ mutex_lock(&device_list_lock);
list_del(&spidev->device_entry);
dev_set_drvdata(&spi->dev, NULL);
clear_bit(MINOR(spidev->dev.devt), minors);
device_unregister(&spidev->dev);
-
mutex_unlock(&device_list_lock);
return 0;