2023-12-10 10:28:21

by Dinghao Liu

Subject: [PATCH] nvdimm-btt: simplify code with the scope based resource management

Use the scope based resource management (defined in
linux/cleanup.h) to automate resource lifetime
control on struct btt_sb *super in discover_arenas().

Signed-off-by: Dinghao Liu <[email protected]>
---
drivers/nvdimm/btt.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index d5593b0dc700..ff42778b51de 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -16,6 +16,7 @@
#include <linux/fs.h>
#include <linux/nd.h>
#include <linux/backing-dev.h>
+#include <linux/cleanup.h>
#include "btt.h"
#include "nd.h"

@@ -847,7 +848,7 @@ static int discover_arenas(struct btt *btt)
{
int ret = 0;
struct arena_info *arena;
- struct btt_sb *super;
+ struct btt_sb *super __free(kfree) = NULL;
size_t remaining = btt->rawsize;
u64 cur_nlba = 0;
size_t cur_off = 0;
@@ -860,10 +861,8 @@ static int discover_arenas(struct btt *btt)
while (remaining) {
/* Alloc memory for arena */
arena = alloc_arena(btt, 0, 0, 0);
- if (!arena) {
- ret = -ENOMEM;
- goto out_super;
- }
+ if (!arena)
+ return -ENOMEM;

arena->infooff = cur_off;
ret = btt_info_read(arena, super);
@@ -919,14 +918,11 @@ static int discover_arenas(struct btt *btt)
btt->nlba = cur_nlba;
btt->init_state = INIT_READY;

- kfree(super);
return ret;

out:
kfree(arena);
free_arenas(btt);
- out_super:
- kfree(super);
return ret;
}

--
2.17.1

2023-12-11 18:27:38

by Dave Jiang

Subject: Re: [PATCH] nvdimm-btt: simplify code with the scope based resource management

On 12/10/23 03:27, Dinghao Liu wrote:
> Use the scope based resource management (defined in
> linux/cleanup.h) to automate resource lifetime
> control on struct btt_sb *super in discover_arenas().
>
> Signed-off-by: Dinghao Liu <[email protected]>
> ---
> drivers/nvdimm/btt.c | 12 ++++--------
> 1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index d5593b0dc700..ff42778b51de 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -16,6 +16,7 @@
> #include <linux/fs.h>
> #include <linux/nd.h>
> #include <linux/backing-dev.h>
> +#include <linux/cleanup.h>
> #include "btt.h"
> #include "nd.h"
>
> @@ -847,7 +848,7 @@ static int discover_arenas(struct btt *btt)
> {
> int ret = 0;
> struct arena_info *arena;
> - struct btt_sb *super;
> + struct btt_sb *super __free(kfree) = NULL;
> size_t remaining = btt->rawsize;
> u64 cur_nlba = 0;
> size_t cur_off = 0;
> @@ -860,10 +861,8 @@ static int discover_arenas(struct btt *btt)
> while (remaining) {
> /* Alloc memory for arena */
> arena = alloc_arena(btt, 0, 0, 0);
> - if (!arena) {
> - ret = -ENOMEM;
> - goto out_super;
> - }
> + if (!arena)
> + return -ENOMEM;
>
> arena->infooff = cur_off;
> ret = btt_info_read(arena, super);
> @@ -919,14 +918,11 @@ static int discover_arenas(struct btt *btt)
> btt->nlba = cur_nlba;
> btt->init_state = INIT_READY;
>
> - kfree(super);
> return ret;
>
> out:
> kfree(arena);
> free_arenas(btt);
> - out_super:
> - kfree(super);
> return ret;
> }
>

I would do the allocation like something below for the first chunk. Otherwise the rest LGTM.

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index d5593b0dc700..143921e7f26c 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -16,6 +16,7 @@
#include <linux/fs.h>
#include <linux/nd.h>
#include <linux/backing-dev.h>
+#include <linux/cleanup.h>
#include "btt.h"
#include "nd.h"

@@ -845,25 +846,23 @@ static void parse_arena_meta(struct arena_info *arena, struct btt_sb *super,

static int discover_arenas(struct btt *btt)
{
+ struct btt_sb *super __free(kfree) =
+ kzalloc(sizeof(*super), GFP_KERNEL);
int ret = 0;
struct arena_info *arena;
- struct btt_sb *super;
size_t remaining = btt->rawsize;
u64 cur_nlba = 0;
size_t cur_off = 0;
int num_arenas = 0;

- super = kzalloc(sizeof(*super), GFP_KERNEL);
if (!super)
return -ENOMEM;

while (remaining) {
/* Alloc memory for arena */
arena = alloc_arena(btt, 0, 0, 0);
- if (!arena) {
- ret = -ENOMEM;
- goto out_super;
- }
+ if (!arena)
+ return -ENOMEM;

arena->infooff = cur_off;
ret = btt_info_read(arena, super);

2023-12-13 03:12:36

by Dinghao Liu

Subject: Re: [PATCH] nvdimm-btt: simplify code with the scope based resource management

>
> On 12/10/23 03:27, Dinghao Liu wrote:
> > Use the scope based resource management (defined in
> > linux/cleanup.h) to automate resource lifetime
> > control on struct btt_sb *super in discover_arenas().
> >
> > Signed-off-by: Dinghao Liu <[email protected]>
> > ---
> > drivers/nvdimm/btt.c | 12 ++++--------
> > 1 file changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> > index d5593b0dc700..ff42778b51de 100644
> > --- a/drivers/nvdimm/btt.c
> > +++ b/drivers/nvdimm/btt.c
> > @@ -16,6 +16,7 @@
> > #include <linux/fs.h>
> > #include <linux/nd.h>
> > #include <linux/backing-dev.h>
> > +#include <linux/cleanup.h>
> > #include "btt.h"
> > #include "nd.h"
> >
> > @@ -847,7 +848,7 @@ static int discover_arenas(struct btt *btt)
> > {
> > int ret = 0;
> > struct arena_info *arena;
> > - struct btt_sb *super;
> > + struct btt_sb *super __free(kfree) = NULL;
> > size_t remaining = btt->rawsize;
> > u64 cur_nlba = 0;
> > size_t cur_off = 0;
> > @@ -860,10 +861,8 @@ static int discover_arenas(struct btt *btt)
> > while (remaining) {
> > /* Alloc memory for arena */
> > arena = alloc_arena(btt, 0, 0, 0);
> > - if (!arena) {
> > - ret = -ENOMEM;
> > - goto out_super;
> > - }
> > + if (!arena)
> > + return -ENOMEM;
> >
> > arena->infooff = cur_off;
> > ret = btt_info_read(arena, super);
> > @@ -919,14 +918,11 @@ static int discover_arenas(struct btt *btt)
> > btt->nlba = cur_nlba;
> > btt->init_state = INIT_READY;
> >
> > - kfree(super);
> > return ret;
> >
> > out:
> > kfree(arena);
> > free_arenas(btt);
> > - out_super:
> > - kfree(super);
> > return ret;
> > }
> >
>
> I would do the allocation like something below for the first chunk. Otherwise the rest LGTM.
>
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index d5593b0dc700..143921e7f26c 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -16,6 +16,7 @@
> #include <linux/fs.h>
> #include <linux/nd.h>
> #include <linux/backing-dev.h>
> +#include <linux/cleanup.h>
> #include "btt.h"
> #include "nd.h"
>
> @@ -845,25 +846,23 @@ static void parse_arena_meta(struct arena_info *arena, struct btt_sb *super,
>
> static int discover_arenas(struct btt *btt)
> {
> + struct btt_sb *super __free(kfree) =
> + kzalloc(sizeof(*super), GFP_KERNEL);
> int ret = 0;
> struct arena_info *arena;
> - struct btt_sb *super;
> size_t remaining = btt->rawsize;
> u64 cur_nlba = 0;
> size_t cur_off = 0;
> int num_arenas = 0;
>
> - super = kzalloc(sizeof(*super), GFP_KERNEL);
> if (!super)
> return -ENOMEM;
>
> while (remaining) {
> /* Alloc memory for arena */

It's a little strange that we do not check super immediately after allocation.
How about this:

static int discover_arenas(struct btt *btt)
{
int ret = 0;
struct arena_info *arena;
- struct btt_sb *super;
size_t remaining = btt->rawsize;
u64 cur_nlba = 0;
size_t cur_off = 0;
int num_arenas = 0;

- super = kzalloc(sizeof(*super), GFP_KERNEL);
+ struct btt_sb *super __free(kfree) =
+ kzalloc(sizeof(*super), GFP_KERNEL);
if (!super)
return -ENOMEM;

while (remaining) {

2023-12-13 16:48:43

by Dave Jiang

Subject: Re: [PATCH] nvdimm-btt: simplify code with the scope based resource management

On 12/12/23 20:12, [email protected] wrote:
>>
>> On 12/10/23 03:27, Dinghao Liu wrote:
>>> Use the scope based resource management (defined in
>>> linux/cleanup.h) to automate resource lifetime
>>> control on struct btt_sb *super in discover_arenas().
>>>
>>> Signed-off-by: Dinghao Liu <[email protected]>
>>> ---
>>> drivers/nvdimm/btt.c | 12 ++++--------
>>> 1 file changed, 4 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
>>> index d5593b0dc700..ff42778b51de 100644
>>> --- a/drivers/nvdimm/btt.c
>>> +++ b/drivers/nvdimm/btt.c
>>> @@ -16,6 +16,7 @@
>>> #include <linux/fs.h>
>>> #include <linux/nd.h>
>>> #include <linux/backing-dev.h>
>>> +#include <linux/cleanup.h>
>>> #include "btt.h"
>>> #include "nd.h"
>>>
>>> @@ -847,7 +848,7 @@ static int discover_arenas(struct btt *btt)
>>> {
>>> int ret = 0;
>>> struct arena_info *arena;
>>> - struct btt_sb *super;
>>> + struct btt_sb *super __free(kfree) = NULL;
>>> size_t remaining = btt->rawsize;
>>> u64 cur_nlba = 0;
>>> size_t cur_off = 0;
>>> @@ -860,10 +861,8 @@ static int discover_arenas(struct btt *btt)
>>> while (remaining) {
>>> /* Alloc memory for arena */
>>> arena = alloc_arena(btt, 0, 0, 0);
>>> - if (!arena) {
>>> - ret = -ENOMEM;
>>> - goto out_super;
>>> - }
>>> + if (!arena)
>>> + return -ENOMEM;
>>>
>>> arena->infooff = cur_off;
>>> ret = btt_info_read(arena, super);
>>> @@ -919,14 +918,11 @@ static int discover_arenas(struct btt *btt)
>>> btt->nlba = cur_nlba;
>>> btt->init_state = INIT_READY;
>>>
>>> - kfree(super);
>>> return ret;
>>>
>>> out:
>>> kfree(arena);
>>> free_arenas(btt);
>>> - out_super:
>>> - kfree(super);
>>> return ret;
>>> }
>>>
>>
>> I would do the allocation like something below for the first chunk. Otherwise the rest LGTM.
>>
>> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
>> index d5593b0dc700..143921e7f26c 100644
>> --- a/drivers/nvdimm/btt.c
>> +++ b/drivers/nvdimm/btt.c
>> @@ -16,6 +16,7 @@
>> #include <linux/fs.h>
>> #include <linux/nd.h>
>> #include <linux/backing-dev.h>
>> +#include <linux/cleanup.h>
>> #include "btt.h"
>> #include "nd.h"
>>
>> @@ -845,25 +846,23 @@ static void parse_arena_meta(struct arena_info *arena, struct btt_sb *super,
>>
>> static int discover_arenas(struct btt *btt)
>> {
>> + struct btt_sb *super __free(kfree) =
>> + kzalloc(sizeof(*super), GFP_KERNEL);
>> int ret = 0;
>> struct arena_info *arena;
>> - struct btt_sb *super;
>> size_t remaining = btt->rawsize;
>> u64 cur_nlba = 0;
>> size_t cur_off = 0;
>> int num_arenas = 0;
>>
>> - super = kzalloc(sizeof(*super), GFP_KERNEL);
>> if (!super)
>> return -ENOMEM;
>>
>> while (remaining) {
>> /* Alloc memory for arena */
>
> It's a little strange that we do not check super immediately after allocation.
> How about this:
>
> static int discover_arenas(struct btt *btt)
> {
> int ret = 0;
> struct arena_info *arena;
> - struct btt_sb *super;
> size_t remaining = btt->rawsize;
> u64 cur_nlba = 0;
> size_t cur_off = 0;
> int num_arenas = 0;
>
> - super = kzalloc(sizeof(*super), GFP_KERNEL);
> + struct btt_sb *super __free(kfree) =
> + kzalloc(sizeof(*super), GFP_KERNEL);
> if (!super)
> return -ENOMEM;
>
> while (remaining) {
>

That's fine by me

2023-12-14 07:57:15

by Dinghao Liu

Subject: Re: [PATCH] nvdimm-btt: simplify code with the scope based resource management

> > It's a little strange that we do not check super immediately after allocation.
> > How about this:
> >
> > static int discover_arenas(struct btt *btt)
> > {
> > int ret = 0;
> > struct arena_info *arena;
> > - struct btt_sb *super;
> > size_t remaining = btt->rawsize;
> > u64 cur_nlba = 0;
> > size_t cur_off = 0;
> > int num_arenas = 0;
> >
> > - super = kzalloc(sizeof(*super), GFP_KERNEL);
> > + struct btt_sb *super __free(kfree) =
> > + kzalloc(sizeof(*super), GFP_KERNEL);
> > if (!super)
> > return -ENOMEM;
> >
> > while (remaining) {
> >
>
> That's fine by me

I will resend a new patch soon, thanks!

Regards,
Dinghao