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usb: clean up some of the computations in adu_read 

Replace ?: with min to calculate the number of bytes in the secondary buffer,
including changing the data type of data_in_secondary to size_t to be
type-consistent. data_in_secondary can never be negative.

Remove some spurious calculations (copy_to_user returns zero on success),
making one variable redundant (i)

This change does not alter the functionality of the code.

Signed-off-by: Daniel M German <dmg@turingmachine.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Daniel M German 2019-06-21 08:22:40 -07:00 committed by Greg Kroah-Hartman
parent 235e6e0a8d
commit 4850f26abf
1 changed files with 7 additions and 9 deletions
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16
drivers/usb/misc/adutux.c
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@ -343,7 +343,6 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
struct adu_device *dev;
size_t bytes_read = 0;
size_t bytes_to_read = count;
int i;
int retval = 0;
int timeout = 0;
int should_submit = 0;
@ -371,23 +370,22 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
timeout = COMMAND_TIMEOUT;
dev_dbg(&dev->udev->dev, "%s : about to start looping\n", __func__);
while (bytes_to_read) {
int data_in_secondary = dev->secondary_tail - dev->secondary_head;
size_t data_in_secondary = dev->secondary_tail - dev->secondary_head;
dev_dbg(&dev->udev->dev,
"%s : while, data_in_secondary=%d, status=%d\n",
"%s : while, data_in_secondary=%zu, status=%d\n",
__func__, data_in_secondary,
dev->interrupt_in_urb->status);
if (data_in_secondary) {
/* drain secondary buffer */
int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
if (i) {
size_t amount = min(bytes_to_read, data_in_secondary);
if (copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount)) {
retval = -EFAULT;
goto exit;
}
dev->secondary_head += (amount - i);
bytes_read += (amount - i);
bytes_to_read -= (amount - i);
dev->secondary_head += amount;
bytes_read += amount;
bytes_to_read -= amount;
} else {
/* we check the primary buffer */
spin_lock_irqsave (&dev->buflock, flags);