[PATCH 05/16] vc_screen: rewrite vcs_size to accept vc, not inode

Jiri Slaby
2020-08-18T08:57:23Z

It is weird to fetch the information from the inode over and over. Read
and write already have the needed information, so rewrite vcs_size to
accept a vc, attr and unicode and adapt vcs_lseek to that.

Also make sure all sites check the return value of vcs_size for errors.

And document it using kernel-doc.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/tty/vt/vc_screen.c | 46 ++++++++++++++++++++++++--------------
1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index adc3c786b621..8aa0d50bcac7 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -202,39 +202,47 @@ static struct vc_data *vcs_vc(struct inode *inode, bool *viewed)
return vc_cons[currcons].d;
}

-/*
- * Returns size for VC carried by inode.
+/**
+ * vcs_size -- return size for a VC in @vc
+ * @vc: which VC
+ * @attr: does it use attributes?
+ * @unicode: is it unicode?
+ *
* Must be called with console_lock.
*/
-static int
-vcs_size(struct inode *inode)
+static int vcs_size(const struct vc_data *vc, bool attr, bool unicode)
{
int size;
- struct vc_data *vc;

WARN_CONSOLE_UNLOCKED();

- vc = vcs_vc(inode, NULL);
- if (!vc)
- return -ENXIO;
-
size = vc->vc_rows * vc->vc_cols;

- if (use_attributes(inode)) {
- if (use_unicode(inode))
+ if (attr) {
+ if (unicode)
return -EOPNOTSUPP;
- size = 2*size + HEADER_SIZE;
- } else if (use_unicode(inode))
+
+ size = 2 * size + HEADER_SIZE;
+ } else if (unicode)
size *= 4;
+
return size;
}

static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
{
+ struct inode *inode = file_inode(file);
+ struct vc_data *vc;
int size;

console_lock();
- size = vcs_size(file_inode(file));
+ vc = vcs_vc(inode, NULL);
+ if (!vc) {
+ console_unlock();
+ return -ENXIO;
+ }
+
+ size = vcs_size(vc, use_attributes(inode), use_unicode(inode));
console_unlock();
if (size < 0)
return size;
@@ -295,7 +303,7 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
* as copy_to_user at the end of this loop
* could sleep.
*/
- size = vcs_size(inode);
+ size = vcs_size(vc, attr, uni_mode);
if (size < 0) {
if (read)
break;
@@ -480,7 +488,11 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
if (!vc)
goto unlock_out;

- size = vcs_size(inode);
+ size = vcs_size(vc, attr, false);
+ if (size < 0) {
+ ret = size;
+ goto unlock_out;
+ }
ret = -EINVAL;
if (pos < 0 || pos > size)
goto unlock_out;
@@ -519,7 +531,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
* the user buffer, so recheck.
* Return data written up to now on failure.
*/
- size = vcs_size(inode);
+ size = vcs_size(vc, attr, false);
if (size < 0) {
if (written)
break;
--
2.28.0