From: Dmitry Osipenko <digetx@gmail.com>
To: Minchan Kim <minchan@kernel.org>, John Hubbard <jhubbard@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
gregkh@linuxfoundation.org, surenb@google.com,
joaodias@google.com, willy@infradead.org
Subject: Re: [PATCH v6] mm: cma: support sysfs
Date: Wed, 24 Mar 2021 15:37:02 +0300 [thread overview]
Message-ID: <5b1a9f6c-ea7b-6e90-1c77-a49a10896f08@gmail.com> (raw)
In-Reply-To: <YFrRugjVLlazTNPy@google.com>
24.03.2021 08:44, Minchan Kim пишет:
> On Tue, Mar 23, 2021 at 09:47:27PM -0700, John Hubbard wrote:
>> On 3/23/21 8:27 PM, Minchan Kim wrote:
>> ...
>>>>> +static int __init cma_sysfs_init(void)
>>>>> +{
>>>>> + unsigned int i;
>>>>> +
>>>>> + cma_kobj_root = kobject_create_and_add("cma", mm_kobj);
>>>>> + if (!cma_kobj_root)
>>>>> + return -ENOMEM;
>>>>> +
>>>>> + for (i = 0; i < cma_area_count; i++) {
>>>>> + int err;
>>>>> + struct cma *cma;
>>>>> + struct cma_kobject *cma_kobj;
>>>>> +
>>>>> + cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL);
>>>>> + if (!cma_kobj) {
>>>>> + kobject_put(cma_kobj_root);
>>>>> + return -ENOMEM;
>>>>
>>>> This leaks little cma_kobj's all over the floor. :)
>>>
>>> I thought kobject_put(cma_kobj_root) should deal with it. No?
>>>
>> If this fails when i > 0, there will be cma_kobj instances that
>> were stashed in the cma_areas[] array. But this code only deletes
>> the most recently allocated cma_kobj, not anything allocated on
>> previous iterations of the loop.
>
> Oh, I misunderstood that destroying of root kobject will release
> children recursively. Seems not true. Go back to old version.
>
>
> index 16c81c9cb9b7..418951a3f138 100644
> --- a/mm/cma_sysfs.c
> +++ b/mm/cma_sysfs.c
> @@ -80,20 +80,19 @@ static struct kobj_type cma_ktype = {
> static int __init cma_sysfs_init(void)
> {
> unsigned int i;
> + int err;
> + struct cma *cma;
> + struct cma_kobject *cma_kobj;
>
> cma_kobj_root = kobject_create_and_add("cma", mm_kobj);
> if (!cma_kobj_root)
> return -ENOMEM;
>
> for (i = 0; i < cma_area_count; i++) {
> - int err;
> - struct cma *cma;
> - struct cma_kobject *cma_kobj;
> -
> cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL);
> if (!cma_kobj) {
> - kobject_put(cma_kobj_root);
> - return -ENOMEM;
> + err = -ENOMEM;
> + goto out;
> }
>
> cma = &cma_areas[i];
> @@ -103,11 +102,21 @@ static int __init cma_sysfs_init(void)
> cma_kobj_root, "%s", cma->name);
> if (err) {
> kobject_put(&cma_kobj->kobj);
> - kobject_put(cma_kobj_root);
> - return err;
> + goto out;
> }
> }
>
> return 0;
> +out:
> + while (--i >= 0) {
> + cma = &cma_areas[i];
> +
> + kobject_put(&cma->kobj->kobj);
> + kfree(cma->kobj);
> + cma->kobj = NULL;
> + }
> + kobject_put(cma_kobj_root);
> +
> + return err;
> }
> subsys_initcall(cma_sysfs_init);
Since we don't care about the order in which kobjects are put, I'd write it in this way, which I think looks cleaner:
static void cma_sysfs_cleanup(struct kobject *cma_kobj_root)
{
struct cma *cma = cma_areas;
unsigned int i;
for (i = 0; i < cma_area_count; i++, cma++) {
if (!cma->kobj)
break;
kobject_put(&cma->kobj->kobj);
}
kobject_put(cma_kobj_root);
}
static int __init cma_sysfs_init(void)
{
struct kobject *cma_kobj_root;
unsigned int i;
cma_kobj_root = kobject_create_and_add("cma", mm_kobj);
if (!cma_kobj_root)
return -ENOMEM;
for (i = 0; i < cma_area_count; i++) {
struct cma_kobject *cma_kobj;
struct cma *cma;
int err;
cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL);
if (!cma_kobj) {
cma_sysfs_cleanup(cma_kobj_root);
return -ENOMEM;
}
cma = &cma_areas[i];
cma->kobj = cma_kobj;
cma_kobj->cma = cma;
err = kobject_init_and_add(&cma_kobj->kobj, &cma_ktype,
cma_kobj_root, "%s", cma->name);
if (err) {
cma_sysfs_cleanup(cma_kobj_root);
return err;
}
}
return 0;
}
subsys_initcall(cma_sysfs_init);
next prev parent reply other threads:[~2021-03-24 12:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-24 1:05 [PATCH v6] mm: cma: support sysfs Minchan Kim
2021-03-24 2:34 ` John Hubbard
2021-03-24 3:27 ` Minchan Kim
2021-03-24 4:47 ` John Hubbard
2021-03-24 5:44 ` Minchan Kim
2021-03-24 6:26 ` John Hubbard
2021-03-24 6:57 ` Minchan Kim
2021-03-24 7:10 ` John Hubbard
2021-03-24 12:37 ` Dmitry Osipenko [this message]
2021-03-24 15:18 ` Minchan Kim
2021-03-24 12:33 ` Dmitry Osipenko
2021-03-24 15:12 ` Minchan Kim
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