diff options
Diffstat (limited to 'drivers/staging/comedi/comedi_fops.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 8c784c483c3e..4dd42890c641 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2346,6 +2346,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, add_wait_queue(&async->wait_head, &wait); while (count == 0 && !retval) { unsigned runflags; + unsigned int wp, n1, n2; set_current_state(TASK_INTERRUPTIBLE); @@ -2360,9 +2361,6 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, /* Allocate all free buffer space. */ comedi_buf_write_alloc(s, async->prealloc_bufsz); m = comedi_buf_write_n_allocated(s); - /* Avoid buffer wraparound. */ - if (async->buf_write_ptr + m > async->prealloc_bufsz) - m = async->prealloc_bufsz - async->buf_write_ptr; n = min_t(size_t, m, nbytes); if (n == 0) { @@ -2388,8 +2386,14 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, continue; } - m = copy_from_user(async->prealloc_buf + async->buf_write_ptr, - buf, n); + wp = async->buf_write_ptr; + n1 = min(n, async->prealloc_bufsz - wp); + n2 = n - n1; + m = copy_from_user(async->prealloc_buf + wp, buf, n1); + if (m) + m += n2; + else if (n2) + m = copy_from_user(async->prealloc_buf, buf + n1, n2); if (m) { n -= m; retval = -EFAULT; |