[PATCH 33/36] tty/vt: consolemap: change refcount only if needed in con_do_clear_unimap()

Jiri Slaby
2022-06-07T10:54:17Z

con_do_clear_unimap() currently decreases and increases refcount of old
dictionary in a back and forth fashion. This makes the code really hard
to follow. Decrease the refcount only if everything went well and we
really allocated a new one and decoupled from the old dictionary.

I sincerelly hope I did not make a mistake in this (ill) logic.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/tty/vt/consolemap.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 01b7e49f1f91..4d8efe74315c 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -535,22 +535,23 @@ static int con_do_clear_unimap(struct vc_data *vc)
{
struct uni_pagedict *old = *vc->vc_uni_pagedir_loc;

- if (!old || --old->refcount) {
+ if (!old || old->refcount > 1) {
struct uni_pagedict *new = kzalloc(sizeof(*new), GFP_KERNEL);
- if (!new) {
- if (old)
- old->refcount++;
+ if (!new)
return -ENOMEM;
- }
+
new->refcount = 1;
*vc->vc_uni_pagedir_loc = new;
+
+ if (old)
+ old->refcount--;
} else {
if (old == dflt)
dflt = NULL;
- old->refcount++;
old->sum = 0;
con_release_unimap(old);
}
+
return 0;
}

--
2.36.1