[KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c

[KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c

[Shani Moideen]

Hi,

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c.

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

thanks.


diff --git a/mm/memory.c b/mm/memory.c
index e7066e7..2780d07 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1505,7 +1505,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
                 * zeroes.
                 */
                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
-                       memset(kaddr, 0, PAGE_SIZE);
+                       clear_page(kaddr);
                kunmap_atomic(kaddr, KM_USER0);
                flush_dcache_page(dst);
                return;


-- 
Shani 

[KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c

[Shani Moideen]

Hi,

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c.

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

thanks.


diff --git a/mm/memory.c b/mm/memory.c
index e7066e7..2780d07 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1505,7 +1505,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
                 * zeroes.
                 */
                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
-                       memset(kaddr, 0, PAGE_SIZE);
+                       clear_page(kaddr);
                kunmap_atomic(kaddr, KM_USER0);
                flush_dcache_page(dst);
                return;


-- 
Shani 

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[KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in kernel/kexec.c

[Shani Moideen]

Hi,

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in
kernel/kexec.c 

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

thanks.


diff --git a/kernel/kexec.c b/kernel/kexec.c
index 2a59c8a..1a1afdd 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -787,7 +787,7 @@ static int kimage_load_normal_segment(struct kimage *image,

                ptr = kmap(page);
                /* Start with a clear page */
-               memset(ptr, 0, PAGE_SIZE);
+               clear_page(ptr);
                ptr += maddr & ~PAGE_MASK;
                mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
                if (mchunk > mbytes)






-- 
Shani 

[KJ] [KJ PATCH] Replacing memset(<addr>, 0,

[Shani Moideen]

Hi,

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c.

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

thanks.


diff --git a/mm/memory.c b/mm/memory.c
index e7066e7..2780d07 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1505,7 +1505,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
                 * zeroes.
                 */
                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
-                       memset(kaddr, 0, PAGE_SIZE);
+                       clear_page(kaddr);
                kunmap_atomic(kaddr, KM_USER0);
                flush_dcache_page(dst);
                return;


-- 
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[KJ] [KJ PATCH] Replacing memset(<addr>, 0,

[Shani Moideen]

Hi,

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in
kernel/kexec.c 

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

thanks.


diff --git a/kernel/kexec.c b/kernel/kexec.c
index 2a59c8a..1a1afdd 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -787,7 +787,7 @@ static int kimage_load_normal_segment(struct kimage *image,

                ptr = kmap(page);
                /* Start with a clear page */
-               memset(ptr, 0, PAGE_SIZE);
+               clear_page(ptr);
                ptr += maddr & ~PAGE_MASK;
                mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
                if (mchunk > mbytes)






-- 
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[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[Michael Tokarev]

Shani Moideen wrote:
>                 ptr = kmap(page);
> -               memset(ptr, 0, PAGE_SIZE);
> +               clear_page(ptr);

I wonder if it's worth to invent kzmap() or something like that... ;)

/mjt
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Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in kernel/kexec.c

[Michael Tokarev]

Shani Moideen wrote:
>                 ptr = kmap(page);
> -               memset(ptr, 0, PAGE_SIZE);
> +               clear_page(ptr);

I wonder if it's worth to invent kzmap() or something like that... ;)

/mjt

[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[Andy Whitcroft]

Shani Moideen wrote:
> Hi,
> 
> Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c.
> 
> Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
> ----
> 
> thanks.
> 
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index e7066e7..2780d07 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1505,7 +1505,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
>                  * zeroes.
>                  */
>                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
> -                       memset(kaddr, 0, PAGE_SIZE);
> +                       clear_page(kaddr);
>                 kunmap_atomic(kaddr, KM_USER0);
>                 flush_dcache_page(dst);
>                 return;
> 
> 

This looks to be whitespace dammaged?

-apw

use tabs not spaces
PATCH: -:64:
FILE: b/mm/memory.c:1508:
+                       clear_page(kaddr);$

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Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c

[Andy Whitcroft]

Shani Moideen wrote:
> Hi,
> 
> Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c.
> 
> Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
> ----
> 
> thanks.
> 
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index e7066e7..2780d07 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1505,7 +1505,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
>                  * zeroes.
>                  */
>                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
> -                       memset(kaddr, 0, PAGE_SIZE);
> +                       clear_page(kaddr);
>                 kunmap_atomic(kaddr, KM_USER0);
>                 flush_dcache_page(dst);
>                 return;
> 
> 

This looks to be whitespace dammaged?

-apw

use tabs not spaces
PATCH: -:64:
FILE: b/mm/memory.c:1508:
+                       clear_page(kaddr);$

Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c

[Andy Whitcroft]

Shani Moideen wrote:
> Hi,
> 
> Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in mm/memory.c.
> 
> Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
> ----
> 
> thanks.
> 
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index e7066e7..2780d07 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1505,7 +1505,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
>                  * zeroes.
>                  */
>                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
> -                       memset(kaddr, 0, PAGE_SIZE);
> +                       clear_page(kaddr);
>                 kunmap_atomic(kaddr, KM_USER0);
>                 flush_dcache_page(dst);
>                 return;
> 
> 

This looks to be whitespace dammaged?

-apw

use tabs not spaces
PATCH: -:64:
FILE: b/mm/memory.c:1508:
+                       clear_page(kaddr);$

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[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[Pekka Enberg]

Shani Moideen wrote:
> >                 ptr = kmap(page);
> > -               memset(ptr, 0, PAGE_SIZE);
> > +               clear_page(ptr);

On 5/8/07, Michael Tokarev <mjt@tls.msk.ru> wrote:
> I wonder if it's worth to invent kzmap() or something like that... ;)

I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
worth it to reduce kernel text size.
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Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in kernel/kexec.c

[Pekka Enberg]

Shani Moideen wrote:
> >                 ptr = kmap(page);
> > -               memset(ptr, 0, PAGE_SIZE);
> > +               clear_page(ptr);

On 5/8/07, Michael Tokarev <mjt@tls.msk.ru> wrote:
> I wonder if it's worth to invent kzmap() or something like that... ;)

I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
worth it to reduce kernel text size.

[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[Satyam Sharma]

On 5/8/07, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> Shani Moideen wrote:
> > >                 ptr = kmap(page);
> > > -               memset(ptr, 0, PAGE_SIZE);
> > > +               clear_page(ptr);
>
> On 5/8/07, Michael Tokarev <mjt@tls.msk.ru> wrote:
> > I wonder if it's worth to invent kzmap() or something like that... ;)
>
> I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
> worth it to reduce kernel text size.

Stuff of the sort already exists. Look for clear_highpage(),
clear_user_highpage() and memclear_highpage_flush (recently renamed to
zero_user_page, see -mm). But they all use kmap_atomic() -- kmap()
variants would have to be added. Also, they're all inlines, so I'm not
sure you'd be able to cut down text size, but still getting rid of
open-coding is always good.
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Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in kernel/kexec.c

[Satyam Sharma]

On 5/8/07, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> Shani Moideen wrote:
> > >                 ptr = kmap(page);
> > > -               memset(ptr, 0, PAGE_SIZE);
> > > +               clear_page(ptr);
>
> On 5/8/07, Michael Tokarev <mjt@tls.msk.ru> wrote:
> > I wonder if it's worth to invent kzmap() or something like that... ;)
>
> I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
> worth it to reduce kernel text size.

Stuff of the sort already exists. Look for clear_highpage(),
clear_user_highpage() and memclear_highpage_flush (recently renamed to
zero_user_page, see -mm). But they all use kmap_atomic() -- kmap()
variants would have to be added. Also, they're all inlines, so I'm not
sure you'd be able to cut down text size, but still getting rid of
open-coding is always good.

[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[Eric W. Biederman]

"Satyam Sharma" <satyam.sharma@gmail.com> writes:

> On 5/8/07, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
>> Shani Moideen wrote:
>> > >                 ptr = kmap(page);
>> > > -               memset(ptr, 0, PAGE_SIZE);
>> > > +               clear_page(ptr);
>>
>> On 5/8/07, Michael Tokarev <mjt@tls.msk.ru> wrote:
>> > I wonder if it's worth to invent kzmap() or something like that... ;)
>>
>> I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
>> worth it to reduce kernel text size.
>
> Stuff of the sort already exists. Look for clear_highpage(),
> clear_user_highpage() and memclear_highpage_flush (recently renamed to
> zero_user_page, see -mm). But they all use kmap_atomic() -- kmap()
> variants would have to be added. Also, they're all inlines, so I'm not
> sure you'd be able to cut down text size, but still getting rid of
> open-coding is always good.

In this instance a clear_page variant should be ok.  The combined
variants are likely not because I use the mapping after it is cleared.

Eric



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Re: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with clear_page() in kernel/kexec.c

[Eric W. Biederman]

"Satyam Sharma" <satyam.sharma@gmail.com> writes:

> On 5/8/07, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
>> Shani Moideen wrote:
>> > >                 ptr = kmap(page);
>> > > -               memset(ptr, 0, PAGE_SIZE);
>> > > +               clear_page(ptr);
>>
>> On 5/8/07, Michael Tokarev <mjt@tls.msk.ru> wrote:
>> > I wonder if it's worth to invent kzmap() or something like that... ;)
>>
>> I am counting 59 kmap + memset pairs in the kernel, so perhaps it is
>> worth it to reduce kernel text size.
>
> Stuff of the sort already exists. Look for clear_highpage(),
> clear_user_highpage() and memclear_highpage_flush (recently renamed to
> zero_user_page, see -mm). But they all use kmap_atomic() -- kmap()
> variants would have to be added. Also, they're all inlines, so I'm not
> sure you'd be able to cut down text size, but still getting rid of
> open-coding is always good.

In this instance a clear_page variant should be ok.  The combined
variants are likely not because I use the mapping after it is cleared.

Eric

[KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Shani Moideen]

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>) 
in drivers/char/drm/i810_dma.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/char/drm/i810_dma.c b/drivers/char/drm/i810_dma.c
index 603d17f..4dbd97f 100644
--- a/drivers/char/drm/i810_dma.c
+++ b/drivers/char/drm/i810_dma.c
@@ -413,7 +413,7 @@ static int i810_dma_initialize(drm_device_t * dev,
 		DRM_ERROR("Can not allocate hardware status page\n");
 		return -ENOMEM;
 	}
-	memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
+	clear_page(dev_priv->hw_status_page);
 	DRM_DEBUG("hw status page @ %p\n", dev_priv->hw_status_page);
 
 	I810_WRITE(0x02080, dev_priv->dma_status_page);

-- 
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[KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Shani Moideen]

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>) 
in drivers/char/drm/i830_dma.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/char/drm/i830_dma.c b/drivers/char/drm/i830_dma.c
index 3314a9f..2b6632d 100644
--- a/drivers/char/drm/i830_dma.c
+++ b/drivers/char/drm/i830_dma.c
@@ -433,7 +433,7 @@ static int i830_dma_initialize(drm_device_t * dev,
 		DRM_ERROR("Can not allocate hardware status page\n");
 		return -ENOMEM;
 	}
-	memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
+	clear_page(dev_priv->hw_status_page);
 	DRM_DEBUG("hw status page @ %p\n", dev_priv->hw_status_page);
 
 	I830_WRITE(0x02080, dev_priv->dma_status_page);

-- 
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[KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Shani Moideen]

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>)
in drivers/char/drm/i915_dma.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/char/drm/i915_dma.c b/drivers/char/drm/i915_dma.c
index 1ba15d9..4f17eb6 100644
--- a/drivers/char/drm/i915_dma.c
+++ b/drivers/char/drm/i915_dma.c
@@ -191,7 +191,7 @@ static int i915_initialize(drm_device_t * dev,
 	dev_priv->hw_status_page = dev_priv->status_page_dmah->vaddr;
 	dev_priv->dma_status_page = dev_priv->status_page_dmah->busaddr;
 
-	memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
+	clear_page(dev_priv->hw_status_page);
 	DRM_DEBUG("hw status page @ %p\n", dev_priv->hw_status_page);
 
 	I915_WRITE(0x02080, dev_priv->dma_status_page);

-- 
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[KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Shani Moideen]

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>) 
in drivers/infiniband/hw/mthca/mthca_allocator.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/infiniband/hw/mthca/mthca_allocator.c b/drivers/infiniband/hw/mthca/mthca_allocator.c
index f930e55..a763067 100644
--- a/drivers/infiniband/hw/mthca/mthca_allocator.c
+++ b/drivers/infiniband/hw/mthca/mthca_allocator.c
@@ -255,7 +255,7 @@ int mthca_buf_alloc(struct mthca_dev *dev, int size, int max_direct,
 			dma_list[i] = t;
 			pci_unmap_addr_set(&buf->page_list[i], mapping, t);
 
-			memset(buf->page_list[i].buf, 0, PAGE_SIZE);
+			clear_page(buf->page_list[i].buf);
 		}
 	}


-- 
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[KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Shani Moideen]

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>) 
in drivers/infiniband/hw/mthca/mthca_eq.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/infiniband/hw/mthca/mthca_eq.c b/drivers/infiniband/hw/mthca/mthca_eq.c
index 8ec9fa1..8592b26 100644
--- a/drivers/infiniband/hw/mthca/mthca_eq.c
+++ b/drivers/infiniband/hw/mthca/mthca_eq.c
@@ -522,7 +522,7 @@ static int mthca_create_eq(struct mthca_dev *dev,
 		dma_list[i] = t;
 		pci_unmap_addr_set(&eq->page_list[i], mapping, t);
 
-		memset(eq->page_list[i].buf, 0, PAGE_SIZE);
+		clear_page(eq->page_list[i].buf);
 	}
 
 	for (i = 0; i < eq->nent; ++i)


-- 
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[KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Shani Moideen]

Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>) 
in drivers/infiniband/hw/ipath/ipath_driver.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index e3a2232..417e3ca 100644
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -1509,7 +1509,7 @@ int ipath_create_rcvhdrq(struct ipath_devdata *dd,
 
 	/* clear for security and sanity on each use */
 	memset(pd->port_rcvhdrq, 0, pd->port_rcvhdrq_size);
-	memset(pd->port_rcvhdrtail_kvaddr, 0, PAGE_SIZE);
+	clear_page(pd->port_rcvhdrtail_kvaddr);
 
 	/*
 	 * tell chip each time we init it, even if we are re-using previous

-- 
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[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[QLogic Support]

[-- Attachment #1.1: Type: text/plain, Size: 1910 bytes --]

Regards,
 
Steve Newberger
QLogic Corporation
Support@QLogic.com

Please visit our web @
http://support.qlogic.com/  


---- Original Message ----
From: shani.moideen@wipro.com
Sent: 17-Jun-2007 22:33:56
To: support@pathscale.com
Cc: openib-general@openib.org; kernel-janitors@lists.osdl.org
Subject: [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with	clear_page(<addr>) in drivers/infiniband/hw/ipath/ipath_driver.c



Replacing memset(<addr>,0,PAGE_SIZE) with clear_page(<addr>) 
in drivers/infiniband/hw/ipath/ipath_driver.c

Signed-off-by: Shani Moideen <shani.moideen@wipro.com>
----

diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index e3a2232..417e3ca 100644
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -1509,7 +1509,7 @@ int ipath_create_rcvhdrq(struct ipath_devdata *dd,
 
 	/* clear for security and sanity on each use */
 	memset(pd->port_rcvhdrq, 0, pd->port_rcvhdrq_size);
-	memset(pd->port_rcvhdrtail_kvaddr, 0, PAGE_SIZE);
+	clear_page(pd->port_rcvhdrtail_kvaddr);
 
 	/*
 	 * tell chip each time we init it, even if we are re-using previous

-- 
Shani 


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Re: [KJ] [KJ PATCH] Replacing memset(<addr>,0,PAGE_SIZE) with

[Robert P. J. Day]

On Mon, 18 Jun 2007, Shani Moideen wrote:
...
> -			memset(buf->page_list[i].buf, 0, PAGE_SIZE);
> +			clear_page(buf->page_list[i].buf);
...

i'm not sure whether this current cleanup project was at all inspired
by the page at the wiki:

http://fsdev.net/wiki/index.php?title=Clear_page_copy_page

note that there are two sort of related cleanups -- clear_page() and
copy_page().  but, as you can read there, it's not *entirely* clear
that the clears or copies are entirely equivalent to the corresponding
memset() or memcpy() calls (or whether they should be).

calling memset() for a size of PAGE_SIZE doesn't necessarily mean that
the address is on a page boundary, while it's possible that something
called "clear_page()" is *meant* to work only on an actual page.
that's not what appears to be happening, but it's something to keep in
mind:  *should* something called "clear_page()" have any extra
semantics above and beyond just clearing something that's the size of
a page?

and the same thing can be asked of "copy_page()".  i'm not saying that
there's anything amiss with the current cleaning, and i'm happy to see
it happening.  i'm just curious as to whether the possible semantic
ambiguity has been examined and dismissed.

rday
-- 
====================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
====================================
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[KJ] Re: [KJ PATCH] Replacing memset(<addr>, 0,

[Roland Dreier]

thanks, I applied both mthca patches as one commit.
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