diff options
Diffstat (limited to 'drivers/char/mem.c')
| -rw-r--r-- | drivers/char/mem.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 687d4af6945d..94c2b556cf97 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -726,6 +726,33 @@ static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) return written; } +static ssize_t read_zero(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + size_t cleared = 0; + + while (count) { + size_t chunk = min_t(size_t, count, PAGE_SIZE); + size_t left; + + left = clear_user(buf + cleared, chunk); + if (unlikely(left)) { + cleared += (chunk - left); + if (!cleared) + return -EFAULT; + break; + } + cleared += chunk; + count -= chunk; + + if (signal_pending(current)) + break; + cond_resched(); + } + + return cleared; +} + static int mmap_zero(struct file *file, struct vm_area_struct *vma) { #ifndef CONFIG_MMU @@ -791,7 +818,7 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig) switch (orig) { case SEEK_CUR: offset += file->f_pos; - /* fall through */ + fallthrough; case SEEK_SET: /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ if ((unsigned long long)offset >= -MAX_ERRNO) { @@ -921,6 +948,7 @@ static const struct file_operations zero_fops = { .llseek = zero_lseek, .write = write_zero, .read_iter = read_iter_zero, + .read = read_zero, .write_iter = write_iter_zero, .mmap = mmap_zero, .get_unmapped_area = get_unmapped_area_zero, |