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

Jiri Slaby
2022-06-08T08:17:28Z

On 07. 06. 22, 17:31, Ilpo Järvinen wrote:
> On Tue, 7 Jun 2022, Jiri Slaby wrote:
>
>> 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>
>
> It seems fine:
>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
>
> One unrelated comment below for additional cleanup opportunity.
>
>> ---
>> 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;
>
> This seems unnecessary as con_release_unimap() already does it.

Good point -- the code is real mess... Now, the mess is more apparent,
at least ;).

I will create a separate patch for this.

thanks,
--
js
suse labs