serial2002: switch serial2002_tty_write to kernel_{read/write}

Instead of playing games with the address limit.  This also gains
us proper usage of the write counter, time stamp updates and kvec
validation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/staging/comedi/drivers/serial2002.c b/drivers/staging/comedi/drivers/serial2002.c
index 0d33e520f6350f599d8e2d3b7a6a4a2e561ce960..cc18e25103ca5976dd914de4b2021db28c10b6e6 100644 (file)
--- a/drivers/staging/comedi/drivers/serial2002.c
+++ b/drivers/staging/comedi/drivers/serial2002.c
@@ -106,16 +106,8 @@ static long serial2002_tty_ioctl(struct file *f, unsigned int op,
 
 static int serial2002_tty_write(struct file *f, unsigned char *buf, int count)
 {
-       const char __user *p = (__force const char __user *)buf;
-       int result;
-       loff_t offset = 0;
-       mm_segment_t oldfs;
-
-       oldfs = get_fs();
-       set_fs(KERNEL_DS);
-       result = __vfs_write(f, p, count, &offset);
-       set_fs(oldfs);
-       return result;
+       loff_t pos = 0;
+       return kernel_write(f, buf, count, &pos);
 }
 
 static void serial2002_tty_read_poll_wait(struct file *f, int timeout)
@@ -148,19 +140,14 @@ static int serial2002_tty_read(struct file *f, int timeout)
 {
        unsigned char ch;
        int result;
+       loff_t pos = 0;
 
        result = -1;
        if (!IS_ERR(f)) {
-               mm_segment_t oldfs;
-               char __user *p = (__force char __user *)&ch;
-               loff_t offset = 0;
-
-               oldfs = get_fs();
-               set_fs(KERNEL_DS);
                if (f->f_op->poll) {
                        serial2002_tty_read_poll_wait(f, timeout);
 
-                       if (__vfs_read(f, p, 1, &offset) == 1)
+                       if (kernel_read(f, &ch, 1, &pos) == 1)
                                result = ch;
                } else {
                        /* Device does not support poll, busy wait */
@@ -171,14 +158,13 @@ static int serial2002_tty_read(struct file *f, int timeout)
                                if (retries >= timeout)
                                        break;
 
-                               if (__vfs_read(f, p, 1, &offset) == 1) {
+                               if (kernel_read(f, &ch, 1, &pos) == 1) {
                                        result = ch;
                                        break;
                                }
                                usleep_range(100, 1000);
                        }
                }
-               set_fs(oldfs);
        }
        return result;
 }