Commit 4b1295b0 authored Jul 04, 2008 by Sebastian Siewior Committed by Linus Torvalds Jul 04, 2008

spi: fix the read path in spidev



This got broken by the recent "fix rmmod $spi_driver while spidev-user is
active".  I tested the rmmod & write path but didn't check the read path.
I am sorry.  The read logic changed and spidev_sync_read() +
spidev_sync_write() do not return zero on success anymore but the number
of bytes that has been transfered over the bus.  This patch changes the
logic and copy_to_user() gets called again.

The write path returns the number of bytes which are written to the
underlying device what may be less than the requested size.  This patch
makes the same change to the read path or else we request a read of 20
bytes, get 10, don't call copy to user and report to the user that we read
10 bytes.

[akpm@linux-foundation.org: remove test of known-to-be-zero local]
Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Acked-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>

parent bef67c5a

drivers/spi/spidev.c

+4 −6

Original line number	Diff line number	Diff line
		@@ -167,14 +167,14 @@ spidev_read(struct file filp, char __user buf, size_t count, loff_t *f_pos)

		mutex_lock(&spidev->buf_lock);
		status = spidev_sync_read(spidev, count);
		if (status == 0) {
		if (status > 0) {
		unsigned long missing;

		missing = copy_to_user(buf, spidev->buffer, count);
		if (count && missing == count)
		missing = copy_to_user(buf, spidev->buffer, status);
		if (missing == status)
		status = -EFAULT;
		else
		status = count - missing;
		status = status - missing;
		}
		mutex_unlock(&spidev->buf_lock);

		@@ -200,8 +200,6 @@ spidev_write(struct file filp, const char __user buf,
		missing = copy_from_user(spidev->buffer, buf, count);
		if (missing == 0) {
		status = spidev_sync_write(spidev, count);
		if (status == 0)
		status = count;
		} else
		status = -EFAULT;
		mutex_unlock(&spidev->buf_lock);

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