[PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

From: Hou Tao <houtao1@huawei.com>

__hash_remove() removes hash_cell with _hash_lock locked, so acquiring
_hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
have not been removed and hc->md must still be md.

__hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
as NULL, so in dm_copy_name_and_uuid() after acquiring
dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
hc must still be alive and hc->md must still be md.

So removing these unnecessary hc->md != md checks when using
dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 drivers/md/dm-ioctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 3bfc1583c20a..2a86524661d1 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
 
 	down_read(&_hash_lock);
 	hc = dm_get_mdptr(md);
-	if (!hc || hc->md != md) {
+	if (!hc) {
 		DMERR("device has been removed from the dev hash table.");
 		goto out;
 	}
@@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
 	/* stage inactive table */
 	down_write(&_hash_lock);
 	hc = dm_get_mdptr(md);
-	if (!hc || hc->md != md) {
+	if (!hc) {
 		DMERR("device has been removed from the dev hash table.");
 		up_write(&_hash_lock);
 		r = -ENXIO;
@@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
 
 	mutex_lock(&dm_hash_cells_mutex);
 	hc = dm_get_mdptr(md);
-	if (!hc || hc->md != md) {
+	if (!hc) {
 		r = -ENXIO;
 		goto out;
 	}
-- 
2.29.2

[dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

From: Hou Tao <houtao1@huawei.com>

__hash_remove() removes hash_cell with _hash_lock locked, so acquiring
_hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
have not been removed and hc->md must still be md.

__hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
as NULL, so in dm_copy_name_and_uuid() after acquiring
dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
hc must still be alive and hc->md must still be md.

So removing these unnecessary hc->md != md checks when using
dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 drivers/md/dm-ioctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 3bfc1583c20a..2a86524661d1 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
 
 	down_read(&_hash_lock);
 	hc = dm_get_mdptr(md);
-	if (!hc || hc->md != md) {
+	if (!hc) {
 		DMERR("device has been removed from the dev hash table.");
 		goto out;
 	}
@@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
 	/* stage inactive table */
 	down_write(&_hash_lock);
 	hc = dm_get_mdptr(md);
-	if (!hc || hc->md != md) {
+	if (!hc) {
 		DMERR("device has been removed from the dev hash table.");
 		up_write(&_hash_lock);
 		r = -ENXIO;
@@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
 
 	mutex_lock(&dm_hash_cells_mutex);
 	hc = dm_get_mdptr(md);
-	if (!hc || hc->md != md) {
+	if (!hc) {
 		r = -ENXIO;
 		goto out;
 	}
-- 
2.29.2

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Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

ping ?

On 12/16/2022 12:23 PM, Hou Tao wrote:
> From: Hou Tao <houtao1@huawei.com>
>
> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring
> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
> have not been removed and hc->md must still be md.
>
> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
> as NULL, so in dm_copy_name_and_uuid() after acquiring
> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
> hc must still be alive and hc->md must still be md.
>
> So removing these unnecessary hc->md != md checks when using
> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
>  drivers/md/dm-ioctl.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> index 3bfc1583c20a..2a86524661d1 100644
> --- a/drivers/md/dm-ioctl.c
> +++ b/drivers/md/dm-ioctl.c
> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
>  
>  	down_read(&_hash_lock);
>  	hc = dm_get_mdptr(md);
> -	if (!hc || hc->md != md) {
> +	if (!hc) {
>  		DMERR("device has been removed from the dev hash table.");
>  		goto out;
>  	}
> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
>  	/* stage inactive table */
>  	down_write(&_hash_lock);
>  	hc = dm_get_mdptr(md);
> -	if (!hc || hc->md != md) {
> +	if (!hc) {
>  		DMERR("device has been removed from the dev hash table.");
>  		up_write(&_hash_lock);
>  		r = -ENXIO;
> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
>  
>  	mutex_lock(&dm_hash_cells_mutex);
>  	hc = dm_get_mdptr(md);
> -	if (!hc || hc->md != md) {
> +	if (!hc) {
>  		r = -ENXIO;
>  		goto out;
>  	}

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Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

ping ?

On 12/16/2022 12:23 PM, Hou Tao wrote:
> From: Hou Tao <houtao1@huawei.com>
>
> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring
> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
> have not been removed and hc->md must still be md.
>
> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
> as NULL, so in dm_copy_name_and_uuid() after acquiring
> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
> hc must still be alive and hc->md must still be md.
>
> So removing these unnecessary hc->md != md checks when using
> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
>  drivers/md/dm-ioctl.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> index 3bfc1583c20a..2a86524661d1 100644
> --- a/drivers/md/dm-ioctl.c
> +++ b/drivers/md/dm-ioctl.c
> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
>  
>  	down_read(&_hash_lock);
>  	hc = dm_get_mdptr(md);
> -	if (!hc || hc->md != md) {
> +	if (!hc) {
>  		DMERR("device has been removed from the dev hash table.");
>  		goto out;
>  	}
> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
>  	/* stage inactive table */
>  	down_write(&_hash_lock);
>  	hc = dm_get_mdptr(md);
> -	if (!hc || hc->md != md) {
> +	if (!hc) {
>  		DMERR("device has been removed from the dev hash table.");
>  		up_write(&_hash_lock);
>  		r = -ENXIO;
> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
>  
>  	mutex_lock(&dm_hash_cells_mutex);
>  	hc = dm_get_mdptr(md);
> -	if (!hc || hc->md != md) {
> +	if (!hc) {
>  		r = -ENXIO;
>  		goto out;
>  	}

Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

ping ? Any comments on this clean up patch ?

On 1/18/2023 9:16 PM, Hou Tao wrote:
> ping ?
>
> On 12/16/2022 12:23 PM, Hou Tao wrote:
>> From: Hou Tao <houtao1@huawei.com>
>>
>> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring
>> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
>> have not been removed and hc->md must still be md.
>>
>> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
>> as NULL, so in dm_copy_name_and_uuid() after acquiring
>> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
>> hc must still be alive and hc->md must still be md.
>>
>> So removing these unnecessary hc->md != md checks when using
>> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.
>>
>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>> ---
>>  drivers/md/dm-ioctl.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
>> index 3bfc1583c20a..2a86524661d1 100644
>> --- a/drivers/md/dm-ioctl.c
>> +++ b/drivers/md/dm-ioctl.c
>> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
>>  
>>  	down_read(&_hash_lock);
>>  	hc = dm_get_mdptr(md);
>> -	if (!hc || hc->md != md) {
>> +	if (!hc) {
>>  		DMERR("device has been removed from the dev hash table.");
>>  		goto out;
>>  	}
>> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
>>  	/* stage inactive table */
>>  	down_write(&_hash_lock);
>>  	hc = dm_get_mdptr(md);
>> -	if (!hc || hc->md != md) {
>> +	if (!hc) {
>>  		DMERR("device has been removed from the dev hash table.");
>>  		up_write(&_hash_lock);
>>  		r = -ENXIO;
>> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
>>  
>>  	mutex_lock(&dm_hash_cells_mutex);
>>  	hc = dm_get_mdptr(md);
>> -	if (!hc || hc->md != md) {
>> +	if (!hc) {
>>  		r = -ENXIO;
>>  		goto out;
>>  	}

Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

ping ? Any comments on this clean up patch ?

On 1/18/2023 9:16 PM, Hou Tao wrote:
> ping ?
>
> On 12/16/2022 12:23 PM, Hou Tao wrote:
>> From: Hou Tao <houtao1@huawei.com>
>>
>> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring
>> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
>> have not been removed and hc->md must still be md.
>>
>> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
>> as NULL, so in dm_copy_name_and_uuid() after acquiring
>> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
>> hc must still be alive and hc->md must still be md.
>>
>> So removing these unnecessary hc->md != md checks when using
>> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.
>>
>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>> ---
>>  drivers/md/dm-ioctl.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
>> index 3bfc1583c20a..2a86524661d1 100644
>> --- a/drivers/md/dm-ioctl.c
>> +++ b/drivers/md/dm-ioctl.c
>> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
>>  
>>  	down_read(&_hash_lock);
>>  	hc = dm_get_mdptr(md);
>> -	if (!hc || hc->md != md) {
>> +	if (!hc) {
>>  		DMERR("device has been removed from the dev hash table.");
>>  		goto out;
>>  	}
>> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
>>  	/* stage inactive table */
>>  	down_write(&_hash_lock);
>>  	hc = dm_get_mdptr(md);
>> -	if (!hc || hc->md != md) {
>> +	if (!hc) {
>>  		DMERR("device has been removed from the dev hash table.");
>>  		up_write(&_hash_lock);
>>  		r = -ENXIO;
>> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
>>  
>>  	mutex_lock(&dm_hash_cells_mutex);
>>  	hc = dm_get_mdptr(md);
>> -	if (!hc || hc->md != md) {
>> +	if (!hc) {
>>  		r = -ENXIO;
>>  		goto out;
>>  	}

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Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

ping ? Any comments on this clean up patch ?

On 1/31/2023 9:44 AM, Hou Tao wrote:
> ping ? Any comments on this clean up patch ?
>
> On 1/18/2023 9:16 PM, Hou Tao wrote:
>> ping ?
>>
>> On 12/16/2022 12:23 PM, Hou Tao wrote:
>>> From: Hou Tao <houtao1@huawei.com>
>>>
>>> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring
>>> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
>>> have not been removed and hc->md must still be md.
>>>
>>> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
>>> as NULL, so in dm_copy_name_and_uuid() after acquiring
>>> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
>>> hc must still be alive and hc->md must still be md.
>>>
>>> So removing these unnecessary hc->md != md checks when using
>>> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.
>>>
>>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>>> ---
>>>  drivers/md/dm-ioctl.c | 6 +++---
>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
>>> index 3bfc1583c20a..2a86524661d1 100644
>>> --- a/drivers/md/dm-ioctl.c
>>> +++ b/drivers/md/dm-ioctl.c
>>> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
>>>  
>>>  	down_read(&_hash_lock);
>>>  	hc = dm_get_mdptr(md);
>>> -	if (!hc || hc->md != md) {
>>> +	if (!hc) {
>>>  		DMERR("device has been removed from the dev hash table.");
>>>  		goto out;
>>>  	}
>>> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
>>>  	/* stage inactive table */
>>>  	down_write(&_hash_lock);
>>>  	hc = dm_get_mdptr(md);
>>> -	if (!hc || hc->md != md) {
>>> +	if (!hc) {
>>>  		DMERR("device has been removed from the dev hash table.");
>>>  		up_write(&_hash_lock);
>>>  		r = -ENXIO;
>>> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
>>>  
>>>  	mutex_lock(&dm_hash_cells_mutex);
>>>  	hc = dm_get_mdptr(md);
>>> -	if (!hc || hc->md != md) {
>>> +	if (!hc) {
>>>  		r = -ENXIO;
>>>  		goto out;
>>>  	}
> .

Re: [dm-devel] [PATCH] dm: remove unnecessary check when using dm_get_mdptr()

[Hou Tao]

ping ? Any comments on this clean up patch ?

On 1/31/2023 9:44 AM, Hou Tao wrote:
> ping ? Any comments on this clean up patch ?
>
> On 1/18/2023 9:16 PM, Hou Tao wrote:
>> ping ?
>>
>> On 12/16/2022 12:23 PM, Hou Tao wrote:
>>> From: Hou Tao <houtao1@huawei.com>
>>>
>>> __hash_remove() removes hash_cell with _hash_lock locked, so acquiring
>>> _hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
>>> have not been removed and hc->md must still be md.
>>>
>>> __hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
>>> as NULL, so in dm_copy_name_and_uuid() after acquiring
>>> dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
>>> hc must still be alive and hc->md must still be md.
>>>
>>> So removing these unnecessary hc->md != md checks when using
>>> dm_get_mdptr() with _hash_lock or dm_hash_cells_mutex acquired.
>>>
>>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>>> ---
>>>  drivers/md/dm-ioctl.c | 6 +++---
>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
>>> index 3bfc1583c20a..2a86524661d1 100644
>>> --- a/drivers/md/dm-ioctl.c
>>> +++ b/drivers/md/dm-ioctl.c
>>> @@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
>>>  
>>>  	down_read(&_hash_lock);
>>>  	hc = dm_get_mdptr(md);
>>> -	if (!hc || hc->md != md) {
>>> +	if (!hc) {
>>>  		DMERR("device has been removed from the dev hash table.");
>>>  		goto out;
>>>  	}
>>> @@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
>>>  	/* stage inactive table */
>>>  	down_write(&_hash_lock);
>>>  	hc = dm_get_mdptr(md);
>>> -	if (!hc || hc->md != md) {
>>> +	if (!hc) {
>>>  		DMERR("device has been removed from the dev hash table.");
>>>  		up_write(&_hash_lock);
>>>  		r = -ENXIO;
>>> @@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
>>>  
>>>  	mutex_lock(&dm_hash_cells_mutex);
>>>  	hc = dm_get_mdptr(md);
>>> -	if (!hc || hc->md != md) {
>>> +	if (!hc) {
>>>  		r = -ENXIO;
>>>  		goto out;
>>>  	}
> .

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