Patchwork [v5,03/14] memory-hotplug: remove redundant codes

login
register
mail settings
Submitter Tang Chen
Date Dec. 24, 2012, 12:09 p.m.
Message ID <1356350964-13437-4-git-send-email-tangchen@cn.fujitsu.com>
Download mbox | patch
Permalink /patch/208067/
State Not Applicable
Headers show

Comments

Tang Chen - Dec. 24, 2012, 12:09 p.m.
From: Wen Congyang <wency@cn.fujitsu.com>

offlining memory blocks and checking whether memory blocks are offlined
are very similar. This patch introduces a new function to remove
redundant codes.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 mm/memory_hotplug.c |  101 ++++++++++++++++++++++++++++-----------------------
 1 files changed, 55 insertions(+), 46 deletions(-)
KAMEZAWA Hiroyuki - Dec. 26, 2012, 3:20 a.m.
(2012/12/24 21:09), Tang Chen wrote:
> From: Wen Congyang <wency@cn.fujitsu.com>
> 
> offlining memory blocks and checking whether memory blocks are offlined
> are very similar. This patch introduces a new function to remove
> redundant codes.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>   mm/memory_hotplug.c |  101 ++++++++++++++++++++++++++++-----------------------
>   1 files changed, 55 insertions(+), 46 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index d43d97b..dbb04d8 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1381,20 +1381,14 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
>   	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
>   }
>   
> -int remove_memory(u64 start, u64 size)

please add explanation of this function here. If (*func) returns val other than 0,
this function will fail and returns callback's return value...right ?


> +static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
> +		void *arg, int (*func)(struct memory_block *, void *))
>   {
>   	struct memory_block *mem = NULL;
>   	struct mem_section *section;
> -	unsigned long start_pfn, end_pfn;
>   	unsigned long pfn, section_nr;
>   	int ret;
> -	int return_on_error = 0;
> -	int retry = 0;
> -
> -	start_pfn = PFN_DOWN(start);
> -	end_pfn = start_pfn + PFN_DOWN(size);
>   
> -repeat:

Shouldn't we check lock is held here ? (VM_BUG_ON(!mutex_is_locked(&mem_hotplug_mutex);


>   	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
>   		section_nr = pfn_to_section_nr(pfn);
>   		if (!present_section_nr(section_nr))
> @@ -1411,22 +1405,61 @@ repeat:
>   		if (!mem)
>   			continue;
>   
> -		ret = offline_memory_block(mem);
> +		ret = func(mem, arg);
>   		if (ret) {
> -			if (return_on_error) {
> -				kobject_put(&mem->dev.kobj);
> -				return ret;
> -			} else {
> -				retry = 1;
> -			}
> +			kobject_put(&mem->dev.kobj);
> +			return ret;
>   		}
>   	}
>   
>   	if (mem)
>   		kobject_put(&mem->dev.kobj);
>   
> -	if (retry) {
> -		return_on_error = 1;
> +	return 0;
> +}
> +
> +static int offline_memory_block_cb(struct memory_block *mem, void *arg)
> +{
> +	int *ret = arg;
> +	int error = offline_memory_block(mem);
> +
> +	if (error != 0 && *ret == 0)
> +		*ret = error;
> +
> +	return 0;

Always returns 0 and run through all mem blocks for scan-and-retry, right ?
You need explanation here !


> +}
> +
> +static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
> +{
> +	int ret = !is_memblock_offlined(mem);
> +
> +	if (unlikely(ret))
> +		pr_warn("removing memory fails, because memory "
> +			"[%#010llx-%#010llx] is onlined\n",
> +			PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
> +			PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1);
> +
> +	return ret;
> +}
> +
> +int remove_memory(u64 start, u64 size)
> +{
> +	unsigned long start_pfn, end_pfn;
> +	int ret = 0;
> +	int retry = 1;
> +
> +	start_pfn = PFN_DOWN(start);
> +	end_pfn = start_pfn + PFN_DOWN(size);
> +
> +repeat:

please explan why you repeat here .

> +	walk_memory_range(start_pfn, end_pfn, &ret,
> +			  offline_memory_block_cb);
> +	if (ret) {
> +		if (!retry)
> +			return ret;
> +
> +		retry = 0;
> +		ret = 0;
>   		goto repeat;
>   	}
>   
> @@ -1444,37 +1477,13 @@ repeat:
>   	 * memory blocks are offlined.
>   	 */
>   
> -	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> -		section_nr = pfn_to_section_nr(pfn);
> -		if (!present_section_nr(section_nr))
> -			continue;
> -
> -		section = __nr_to_section(section_nr);
> -		/* same memblock? */
> -		if (mem)
> -			if ((section_nr >= mem->start_section_nr) &&
> -			    (section_nr <= mem->end_section_nr))
> -				continue;
> -
> -		mem = find_memory_block_hinted(section, mem);
> -		if (!mem)
> -			continue;
> -
> -		ret = is_memblock_offlined(mem);
> -		if (!ret) {
> -			pr_warn("removing memory fails, because memory "
> -				"[%#010llx-%#010llx] is onlined\n",
> -				PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
> -				PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1);
> -
> -			kobject_put(&mem->dev.kobj);
> -			unlock_memory_hotplug();
> -			return ret;
> -		}

please explain what you do here. confirming all memory blocks are offlined
before returning 0 ....right ? 

> +	ret = walk_memory_range(start_pfn, end_pfn, NULL,
> +				is_memblock_offlined_cb);
> +	if (ret) {
> +		unlock_memory_hotplug();
> +		return ret;
>   	}
>   
> -	if (mem)
> -		kobject_put(&mem->dev.kobj);
>   	unlock_memory_hotplug();
>   
>   	return 0;
> 

Thanks,
-Kame
Tang Chen - Dec. 27, 2012, 3:09 a.m.
Hi Kamezawa-san,

Thanks for the reviewing. Please see below. :)

On 12/26/2012 11:20 AM, Kamezawa Hiroyuki wrote:
> (2012/12/24 21:09), Tang Chen wrote:
>> From: Wen Congyang<wency@cn.fujitsu.com>
>>
>> offlining memory blocks and checking whether memory blocks are offlined
>> are very similar. This patch introduces a new function to remove
>> redundant codes.
>>
>> Signed-off-by: Wen Congyang<wency@cn.fujitsu.com>
>> ---
>>    mm/memory_hotplug.c |  101 ++++++++++++++++++++++++++++-----------------------
>>    1 files changed, 55 insertions(+), 46 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index d43d97b..dbb04d8 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1381,20 +1381,14 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
>>    	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
>>    }
>>
>> -int remove_memory(u64 start, u64 size)
> 
> please add explanation of this function here. If (*func) returns val other than 0,
> this function will fail and returns callback's return value...right ?
> 

Yes, it will always return the func()'s return value. I'll add the
comment here. :)

> 
>> +static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
>> +		void *arg, int (*func)(struct memory_block *, void *))
>>    {
>>    	struct memory_block *mem = NULL;
>>    	struct mem_section *section;
>> -	unsigned long start_pfn, end_pfn;
>>    	unsigned long pfn, section_nr;
>>    	int ret;
>> -	int return_on_error = 0;
>> -	int retry = 0;
>> -
>> -	start_pfn = PFN_DOWN(start);
>> -	end_pfn = start_pfn + PFN_DOWN(size);
>>
>> -repeat:
> 
> Shouldn't we check lock is held here ? (VM_BUG_ON(!mutex_is_locked(&mem_hotplug_mutex);

Well, I think, after applying this patch, walk_memory_range() will be
a separated function. And it can be used somewhere else where we don't
hold this lock. But for now, we can do this check.  :)

> 
> 
>>    	for (pfn = start_pfn; pfn<  end_pfn; pfn += PAGES_PER_SECTION) {
>>    		section_nr = pfn_to_section_nr(pfn);
>>    		if (!present_section_nr(section_nr))
>> @@ -1411,22 +1405,61 @@ repeat:
>>    		if (!mem)
>>    			continue;
>>
>> -		ret = offline_memory_block(mem);
>> +		ret = func(mem, arg);
>>    		if (ret) {
>> -			if (return_on_error) {
>> -				kobject_put(&mem->dev.kobj);
>> -				return ret;
>> -			} else {
>> -				retry = 1;
>> -			}
>> +			kobject_put(&mem->dev.kobj);
>> +			return ret;
>>    		}
>>    	}
>>
>>    	if (mem)
>>    		kobject_put(&mem->dev.kobj);
>>
>> -	if (retry) {
>> -		return_on_error = 1;
>> +	return 0;
>> +}
>> +
>> +static int offline_memory_block_cb(struct memory_block *mem, void *arg)
>> +{
>> +	int *ret = arg;
>> +	int error = offline_memory_block(mem);
>> +
>> +	if (error != 0&&  *ret == 0)
>> +		*ret = error;
>> +
>> +	return 0;
> 
> Always returns 0 and run through all mem blocks for scan-and-retry, right ?
> You need explanation here !

Yes, I'll add the comment. :)

> 
> 
>> +}
>> +
>> +static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
>> +{
>> +	int ret = !is_memblock_offlined(mem);
>> +
>> +	if (unlikely(ret))
>> +		pr_warn("removing memory fails, because memory "
>> +			"[%#010llx-%#010llx] is onlined\n",
>> +			PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
>> +			PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1);
>> +
>> +	return ret;
>> +}
>> +
>> +int remove_memory(u64 start, u64 size)
>> +{
>> +	unsigned long start_pfn, end_pfn;
>> +	int ret = 0;
>> +	int retry = 1;
>> +
>> +	start_pfn = PFN_DOWN(start);
>> +	end_pfn = start_pfn + PFN_DOWN(size);
>> +
>> +repeat:
> 
> please explan why you repeat here .

This repeat is add in patch1. It aims to solve the problem we were
talking about in patch1. I'll add the comment here. :)

> 
>> +	walk_memory_range(start_pfn, end_pfn,&ret,
>> +			  offline_memory_block_cb);
>> +	if (ret) {
>> +		if (!retry)
>> +			return ret;
>> +
>> +		retry = 0;
>> +		ret = 0;
>>    		goto repeat;
>>    	}
>>
>> @@ -1444,37 +1477,13 @@ repeat:
>>    	 * memory blocks are offlined.
>>    	 */
>>
>> -	for (pfn = start_pfn; pfn<  end_pfn; pfn += PAGES_PER_SECTION) {
>> -		section_nr = pfn_to_section_nr(pfn);
>> -		if (!present_section_nr(section_nr))
>> -			continue;
>> -
>> -		section = __nr_to_section(section_nr);
>> -		/* same memblock? */
>> -		if (mem)
>> -			if ((section_nr>= mem->start_section_nr)&&
>> -			    (section_nr<= mem->end_section_nr))
>> -				continue;
>> -
>> -		mem = find_memory_block_hinted(section, mem);
>> -		if (!mem)
>> -			continue;
>> -
>> -		ret = is_memblock_offlined(mem);
>> -		if (!ret) {
>> -			pr_warn("removing memory fails, because memory "
>> -				"[%#010llx-%#010llx] is onlined\n",
>> -				PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
>> -				PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1);
>> -
>> -			kobject_put(&mem->dev.kobj);
>> -			unlock_memory_hotplug();
>> -			return ret;
>> -		}
> 
> please explain what you do here. confirming all memory blocks are offlined
> before returning 0 ....right ?

Will be added. :)

Thanks. :)

> 
>> +	ret = walk_memory_range(start_pfn, end_pfn, NULL,
>> +				is_memblock_offlined_cb);
>> +	if (ret) {
>> +		unlock_memory_hotplug();
>> +		return ret;
>>    	}
>>
>> -	if (mem)
>> -		kobject_put(&mem->dev.kobj);
>>    	unlock_memory_hotplug();
>>
>>    	return 0;
>>
> 
> Thanks,
> -Kame
> 
>

Patch

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d43d97b..dbb04d8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1381,20 +1381,14 @@  int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
 }
 
-int remove_memory(u64 start, u64 size)
+static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+		void *arg, int (*func)(struct memory_block *, void *))
 {
 	struct memory_block *mem = NULL;
 	struct mem_section *section;
-	unsigned long start_pfn, end_pfn;
 	unsigned long pfn, section_nr;
 	int ret;
-	int return_on_error = 0;
-	int retry = 0;
-
-	start_pfn = PFN_DOWN(start);
-	end_pfn = start_pfn + PFN_DOWN(size);
 
-repeat:
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		section_nr = pfn_to_section_nr(pfn);
 		if (!present_section_nr(section_nr))
@@ -1411,22 +1405,61 @@  repeat:
 		if (!mem)
 			continue;
 
-		ret = offline_memory_block(mem);
+		ret = func(mem, arg);
 		if (ret) {
-			if (return_on_error) {
-				kobject_put(&mem->dev.kobj);
-				return ret;
-			} else {
-				retry = 1;
-			}
+			kobject_put(&mem->dev.kobj);
+			return ret;
 		}
 	}
 
 	if (mem)
 		kobject_put(&mem->dev.kobj);
 
-	if (retry) {
-		return_on_error = 1;
+	return 0;
+}
+
+static int offline_memory_block_cb(struct memory_block *mem, void *arg)
+{
+	int *ret = arg;
+	int error = offline_memory_block(mem);
+
+	if (error != 0 && *ret == 0)
+		*ret = error;
+
+	return 0;
+}
+
+static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
+{
+	int ret = !is_memblock_offlined(mem);
+
+	if (unlikely(ret))
+		pr_warn("removing memory fails, because memory "
+			"[%#010llx-%#010llx] is onlined\n",
+			PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
+			PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1);
+
+	return ret;
+}
+
+int remove_memory(u64 start, u64 size)
+{
+	unsigned long start_pfn, end_pfn;
+	int ret = 0;
+	int retry = 1;
+
+	start_pfn = PFN_DOWN(start);
+	end_pfn = start_pfn + PFN_DOWN(size);
+
+repeat:
+	walk_memory_range(start_pfn, end_pfn, &ret,
+			  offline_memory_block_cb);
+	if (ret) {
+		if (!retry)
+			return ret;
+
+		retry = 0;
+		ret = 0;
 		goto repeat;
 	}
 
@@ -1444,37 +1477,13 @@  repeat:
 	 * memory blocks are offlined.
 	 */
 
-	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
-		section_nr = pfn_to_section_nr(pfn);
-		if (!present_section_nr(section_nr))
-			continue;
-
-		section = __nr_to_section(section_nr);
-		/* same memblock? */
-		if (mem)
-			if ((section_nr >= mem->start_section_nr) &&
-			    (section_nr <= mem->end_section_nr))
-				continue;
-
-		mem = find_memory_block_hinted(section, mem);
-		if (!mem)
-			continue;
-
-		ret = is_memblock_offlined(mem);
-		if (!ret) {
-			pr_warn("removing memory fails, because memory "
-				"[%#010llx-%#010llx] is onlined\n",
-				PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
-				PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1);
-
-			kobject_put(&mem->dev.kobj);
-			unlock_memory_hotplug();
-			return ret;
-		}
+	ret = walk_memory_range(start_pfn, end_pfn, NULL,
+				is_memblock_offlined_cb);
+	if (ret) {
+		unlock_memory_hotplug();
+		return ret;
 	}
 
-	if (mem)
-		kobject_put(&mem->dev.kobj);
 	unlock_memory_hotplug();
 
 	return 0;