staging: comedi: serial2002: fix different address space sparse warnings

The struct file_operations (*read) and (*write) operations expect the
buffer to be a __user space pointer.

Currently the (*write) operations in this driver cause this warning:
warning: incorrect type in argument 2 (different address spaces)
  expected char const [noderef] <asn:1>*<noident>
  got unsigned char [usertype] *buf

And the (*read) operations cause this warning:
warning: incorrect type in argument 2 (different address spaces)
  expected char [noderef] <asn:1>*<noident>
  got unsigned char *<noident>

Use __force to cast the buffer to a __user pointer to suppress the
warnings.

Consolidate the (*read) calls into a helper function, __tty_readb().

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/serial2002.c b/drivers/staging/comedi/drivers/serial2002.c
index e6177b48ccaf7e8b812f7e3055511325426193e6..75c86ae6f84433ef647693640a35496ab38f0117 100644 (file)
--- a/drivers/staging/comedi/drivers/serial2002.c
+++ b/drivers/staging/comedi/drivers/serial2002.c
@@ -82,17 +82,26 @@ static long tty_ioctl(struct file *f, unsigned op, unsigned long param)
 
 static int tty_write(struct file *f, unsigned char *buf, int count)
 {
+       const char __user *p = (__force const char __user *)buf;
        int result;
        mm_segment_t oldfs;
 
        oldfs = get_fs();
        set_fs(KERNEL_DS);
        f->f_pos = 0;
-       result = f->f_op->write(f, buf, count, &f->f_pos);
+       result = f->f_op->write(f, p, count, &f->f_pos);
        set_fs(oldfs);
        return result;
 }
 
+static int __tty_readb(struct file *f, unsigned char *buf)
+{
+       char __user *p = (__force char __user *)buf;
+
+       f->f_pos = 0;
+       return f->f_op->read(f, p, 1, &f->f_pos);
+}
+
 #if 0
 /*
  * On 2.6.26.3 this occaisonally gave me page faults, worked around by
@@ -113,6 +122,7 @@ static int tty_available(struct file *f)
 
 static int tty_read(struct file *f, int timeout)
 {
+       unsigned char ch;
        int result;
 
        result = -1;
@@ -147,25 +157,18 @@ static int tty_read(struct file *f, int timeout)
                                                   elapsed) * HZ) / 10000);
                        }
                        poll_freewait(&table);
-                       {
-                               unsigned char ch;
 
-                               f->f_pos = 0;
-                               if (f->f_op->read(f, &ch, 1, &f->f_pos) == 1)
-                                       result = ch;
-                       }
+                       if (__tty_readb(f, &ch) == 1)
+                               result = ch;
                } else {
                        /* Device does not support poll, busy wait */
                        int retries = 0;
                        while (1) {
-                               unsigned char ch;
-
                                retries++;
                                if (retries >= timeout)
                                        break;
 
-                               f->f_pos = 0;
-                               if (f->f_op->read(f, &ch, 1, &f->f_pos) == 1) {
+                               if (__tty_readb(f, &ch) == 1) {
                                        result = ch;
                                        break;
                                }