* [PATCH] fs: Fix memcpy_sz for remaining count/rwsize
@ 2015-10-08 21:19 Sebastian Hesselbarth
2015-10-12 6:11 ` Sascha Hauer
0 siblings, 1 reply; 6+ messages in thread
From: Sebastian Hesselbarth @ 2015-10-08 21:19 UTC (permalink / raw)
To: Sebastian Hesselbarth; +Cc: barebox
When using memcpy_sz with rwsize != 1 integer division of
count/rwsize may leave some bytes of the request uncopied if
count is not a multiple of rwsize.
Fix this behavior by decrementing count by rwsize instead of
integer division and use plain memcpy for the remaining bytes.
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
---
Cc: barebox@lists.infradead.org
---
fs/fs.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/fs.c b/fs/fs.c
index c041e41bb51b..ccbda22d2692 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1580,9 +1580,7 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
rwsize = rwsize >> O_RWSIZE_SHIFT;
- count /= rwsize;
-
- while (count-- > 0) {
+ while (count > 0) {
switch (rwsize) {
case 1:
*((u8 *)dst) = *((u8 *)src);
@@ -1599,7 +1597,12 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
}
dst += rwsize;
src += rwsize;
+ count -= rwsize;
}
+
+ /* copy remaining bytes with plain memcpy */
+ if (count)
+ memcpy(dst, src, count);
}
ssize_t mem_read(struct cdev *cdev, void *buf, size_t count, loff_t offset, ulong flags)
--
2.1.0
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs: Fix memcpy_sz for remaining count/rwsize
2015-10-08 21:19 [PATCH] fs: Fix memcpy_sz for remaining count/rwsize Sebastian Hesselbarth
@ 2015-10-12 6:11 ` Sascha Hauer
2015-10-12 7:36 ` Sebastian Hesselbarth
0 siblings, 1 reply; 6+ messages in thread
From: Sascha Hauer @ 2015-10-12 6:11 UTC (permalink / raw)
To: Sebastian Hesselbarth; +Cc: barebox
On Thu, Oct 08, 2015 at 11:19:45PM +0200, Sebastian Hesselbarth wrote:
> When using memcpy_sz with rwsize != 1 integer division of
> count/rwsize may leave some bytes of the request uncopied if
> count is not a multiple of rwsize.
>
> Fix this behavior by decrementing count by rwsize instead of
> integer division and use plain memcpy for the remaining bytes.
>
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
> ---
> Cc: barebox@lists.infradead.org
> ---
> fs/fs.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/fs/fs.c b/fs/fs.c
> index c041e41bb51b..ccbda22d2692 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -1580,9 +1580,7 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
>
> rwsize = rwsize >> O_RWSIZE_SHIFT;
>
> - count /= rwsize;
> -
> - while (count-- > 0) {
> + while (count > 0) {
> switch (rwsize) {
> case 1:
> *((u8 *)dst) = *((u8 *)src);
> @@ -1599,7 +1597,12 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
> }
> dst += rwsize;
> src += rwsize;
> + count -= rwsize;
> }
This doesn't look correct. When count > 0 you are inside the loop, so
> +
> + /* copy remaining bytes with plain memcpy */
> + if (count)
> + memcpy(dst, src, count);
here count <= 0 which is no meaningful argument for the copy size.
Should the loop start with while (count >= rwsize) instead?
I wonder if the behaviour shouldn't rather be:
- let memcpy_sz return the number of bytes copied and not copy the
remaining partial word.
- return error from memcpy_sz when input count < rwsize
This would allow us to catch wrongly aligned sizes.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs: Fix memcpy_sz for remaining count/rwsize
2015-10-12 6:11 ` Sascha Hauer
@ 2015-10-12 7:36 ` Sebastian Hesselbarth
2015-10-12 18:51 ` Sebastian Hesselbarth
0 siblings, 1 reply; 6+ messages in thread
From: Sebastian Hesselbarth @ 2015-10-12 7:36 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
On 12.10.2015 08:11, Sascha Hauer wrote:
> On Thu, Oct 08, 2015 at 11:19:45PM +0200, Sebastian Hesselbarth wrote:
>> When using memcpy_sz with rwsize != 1 integer division of
>> count/rwsize may leave some bytes of the request uncopied if
>> count is not a multiple of rwsize.
>>
>> Fix this behavior by decrementing count by rwsize instead of
>> integer division and use plain memcpy for the remaining bytes.
>>
>> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
>> ---
>> Cc: barebox@lists.infradead.org
>> ---
>> fs/fs.c | 9 ++++++---
>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/fs.c b/fs/fs.c
>> index c041e41bb51b..ccbda22d2692 100644
>> --- a/fs/fs.c
>> +++ b/fs/fs.c
>> @@ -1580,9 +1580,7 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
>>
>> rwsize = rwsize >> O_RWSIZE_SHIFT;
>>
>> - count /= rwsize;
>> -
>> - while (count-- > 0) {
>> + while (count > 0) {
>> switch (rwsize) {
>> case 1:
>> *((u8 *)dst) = *((u8 *)src);
>> @@ -1599,7 +1597,12 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
>> }
>> dst += rwsize;
>> src += rwsize;
>> + count -= rwsize;
>> }
>
> This doesn't look correct. When count > 0 you are inside the loop, so
>
>> +
>> + /* copy remaining bytes with plain memcpy */
>> + if (count)
>> + memcpy(dst, src, count);
>
> here count <= 0 which is no meaningful argument for the copy size.
>
> Should the loop start with while (count >= rwsize) instead?
Dammit, last minute cosmetic change including breaking the
whole patch. Sorry for that.
> I wonder if the behaviour shouldn't rather be:
> - let memcpy_sz return the number of bytes copied and not copy the
> remaining partial word.
> - return error from memcpy_sz when input count < rwsize
>
> This would allow us to catch wrongly aligned sizes.
I am open for any different resolution. I stumbled upon the odd
behavior of memcpy_sz while writing to NAND using memcpy. Maybe
it would be also good to always pick byte size for memcpy when
no specific size has been passed. It took me a while until I
realized it is not the NAND controller but memcpy that breaks
the data written by leaving some bytes uncopied.
Sebastian
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs: Fix memcpy_sz for remaining count/rwsize
2015-10-12 7:36 ` Sebastian Hesselbarth
@ 2015-10-12 18:51 ` Sebastian Hesselbarth
2015-10-13 8:00 ` Sascha Hauer
0 siblings, 1 reply; 6+ messages in thread
From: Sebastian Hesselbarth @ 2015-10-12 18:51 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
On 12.10.2015 09:36, Sebastian Hesselbarth wrote:
> On 12.10.2015 08:11, Sascha Hauer wrote:
>> On Thu, Oct 08, 2015 at 11:19:45PM +0200, Sebastian Hesselbarth wrote:
>>> When using memcpy_sz with rwsize != 1 integer division of
>>> count/rwsize may leave some bytes of the request uncopied if
>>> count is not a multiple of rwsize.
>>>
>>> Fix this behavior by decrementing count by rwsize instead of
>>> integer division and use plain memcpy for the remaining bytes.
>>>
>>> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
>>> ---
>>> Cc: barebox@lists.infradead.org
>>> ---
>>> fs/fs.c | 9 ++++++---
>>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/fs.c b/fs/fs.c
>>> index c041e41bb51b..ccbda22d2692 100644
>>> --- a/fs/fs.c
>>> +++ b/fs/fs.c
>>> @@ -1580,9 +1580,7 @@ static void memcpy_sz(void *dst, const void
>>> *src, size_t count, int rwsize)
>>>
>>> rwsize = rwsize >> O_RWSIZE_SHIFT;
>>>
>>> - count /= rwsize;
>>> -
>>> - while (count-- > 0) {
>>> + while (count > 0) {
>>> switch (rwsize) {
>>> case 1:
>>> *((u8 *)dst) = *((u8 *)src);
>>> @@ -1599,7 +1597,12 @@ static void memcpy_sz(void *dst, const void
>>> *src, size_t count, int rwsize)
>>> }
>>> dst += rwsize;
>>> src += rwsize;
>>> + count -= rwsize;
>>> }
>>
>> This doesn't look correct. When count > 0 you are inside the loop, so
>>
>>> +
>>> + /* copy remaining bytes with plain memcpy */
>>> + if (count)
>>> + memcpy(dst, src, count);
>>
>> here count <= 0 which is no meaningful argument for the copy size.
>>
>> Should the loop start with while (count >= rwsize) instead?
>
> Dammit, last minute cosmetic change including breaking the
> whole patch. Sorry for that.
>
>> I wonder if the behaviour shouldn't rather be:
>> - let memcpy_sz return the number of bytes copied and not copy the
>> remaining partial word.
>> - return error from memcpy_sz when input count < rwsize
>>
>> This would allow us to catch wrongly aligned sizes.
>
> I am open for any different resolution. I stumbled upon the odd
> behavior of memcpy_sz while writing to NAND using memcpy. Maybe
> it would be also good to always pick byte size for memcpy when
> no specific size has been passed. It took me a while until I
> realized it is not the NAND controller but memcpy that breaks
> the data written by leaving some bytes uncopied.
Ok, the issue is something different maybe.
I used
memcpy -s /mnt/image.img -d /dev/nand0.u-boot.bb 0 0
i.e. I did not specify any rwsize option. Looking at the code,
mem_parse_options does initialize mode with 0 and memcpy_sz
should use plain memcpy as fallback.
However, if I look at include/fcntl.h, I see that O_RWSIZE_8
collides with O_CREAT. I think that is the root cause of the
64b memcpy_sz issue I am suffering from?
Sebastian
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs: Fix memcpy_sz for remaining count/rwsize
2015-10-12 18:51 ` Sebastian Hesselbarth
@ 2015-10-13 8:00 ` Sascha Hauer
2015-10-13 8:09 ` Sebastian Hesselbarth
0 siblings, 1 reply; 6+ messages in thread
From: Sascha Hauer @ 2015-10-13 8:00 UTC (permalink / raw)
To: Sebastian Hesselbarth; +Cc: barebox
On Mon, Oct 12, 2015 at 08:51:54PM +0200, Sebastian Hesselbarth wrote:
> On 12.10.2015 09:36, Sebastian Hesselbarth wrote:
> >On 12.10.2015 08:11, Sascha Hauer wrote:
> >>On Thu, Oct 08, 2015 at 11:19:45PM +0200, Sebastian Hesselbarth wrote:
> >>>When using memcpy_sz with rwsize != 1 integer division of
> >>>count/rwsize may leave some bytes of the request uncopied if
> >>>count is not a multiple of rwsize.
> >>>
> >>>Fix this behavior by decrementing count by rwsize instead of
> >>>integer division and use plain memcpy for the remaining bytes.
> >>>
> >>>Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
> >>>---
> >>>Cc: barebox@lists.infradead.org
> >>>---
> >>> fs/fs.c | 9 ++++++---
> >>> 1 file changed, 6 insertions(+), 3 deletions(-)
> >>>
> >>>diff --git a/fs/fs.c b/fs/fs.c
> >>>index c041e41bb51b..ccbda22d2692 100644
> >>>--- a/fs/fs.c
> >>>+++ b/fs/fs.c
> >>>@@ -1580,9 +1580,7 @@ static void memcpy_sz(void *dst, const void
> >>>*src, size_t count, int rwsize)
> >>>
> >>> rwsize = rwsize >> O_RWSIZE_SHIFT;
> >>>
> >>>- count /= rwsize;
> >>>-
> >>>- while (count-- > 0) {
> >>>+ while (count > 0) {
> >>> switch (rwsize) {
> >>> case 1:
> >>> *((u8 *)dst) = *((u8 *)src);
> >>>@@ -1599,7 +1597,12 @@ static void memcpy_sz(void *dst, const void
> >>>*src, size_t count, int rwsize)
> >>> }
> >>> dst += rwsize;
> >>> src += rwsize;
> >>>+ count -= rwsize;
> >>> }
> >>
> >>This doesn't look correct. When count > 0 you are inside the loop, so
> >>
> >>>+
> >>>+ /* copy remaining bytes with plain memcpy */
> >>>+ if (count)
> >>>+ memcpy(dst, src, count);
> >>
> >>here count <= 0 which is no meaningful argument for the copy size.
> >>
> >>Should the loop start with while (count >= rwsize) instead?
> >
> >Dammit, last minute cosmetic change including breaking the
> >whole patch. Sorry for that.
> >
> >>I wonder if the behaviour shouldn't rather be:
> >>- let memcpy_sz return the number of bytes copied and not copy the
> >> remaining partial word.
> >>- return error from memcpy_sz when input count < rwsize
> >>
> >>This would allow us to catch wrongly aligned sizes.
> >
> >I am open for any different resolution. I stumbled upon the odd
> >behavior of memcpy_sz while writing to NAND using memcpy. Maybe
> >it would be also good to always pick byte size for memcpy when
> >no specific size has been passed. It took me a while until I
> >realized it is not the NAND controller but memcpy that breaks
> >the data written by leaving some bytes uncopied.
>
> Ok, the issue is something different maybe.
>
> I used
>
> memcpy -s /mnt/image.img -d /dev/nand0.u-boot.bb 0 0
>
> i.e. I did not specify any rwsize option. Looking at the code,
> mem_parse_options does initialize mode with 0 and memcpy_sz
> should use plain memcpy as fallback.
>
> However, if I look at include/fcntl.h, I see that O_RWSIZE_8
> collides with O_CREAT. I think that is the root cause of the
> 64b memcpy_sz issue I am suffering from?
Oh Damned! /me hiding under a brown paper bag.
I don't know how you are calling memcpy_sz, but that could lead to
these kind problems.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs: Fix memcpy_sz for remaining count/rwsize
2015-10-13 8:00 ` Sascha Hauer
@ 2015-10-13 8:09 ` Sebastian Hesselbarth
0 siblings, 0 replies; 6+ messages in thread
From: Sebastian Hesselbarth @ 2015-10-13 8:09 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
On 13.10.2015 10:00, Sascha Hauer wrote:
> On Mon, Oct 12, 2015 at 08:51:54PM +0200, Sebastian Hesselbarth wrote:
>> On 12.10.2015 09:36, Sebastian Hesselbarth wrote:
>> I used
>>
>> memcpy -s /mnt/image.img -d /dev/nand0.u-boot.bb 0 0
>>
>> i.e. I did not specify any rwsize option. Looking at the code,
>> mem_parse_options does initialize mode with 0 and memcpy_sz
>> should use plain memcpy as fallback.
>>
>> However, if I look at include/fcntl.h, I see that O_RWSIZE_8
>> collides with O_CREAT. I think that is the root cause of the
>> 64b memcpy_sz issue I am suffering from?
>
> Oh Damned! /me hiding under a brown paper bag.
>
> I don't know how you are calling memcpy_sz, but that could lead to
> these kind problems.
memcpy_sz is called by fs/fs.c when using memcpy command above.
Sebastian
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2015-10-08 21:19 [PATCH] fs: Fix memcpy_sz for remaining count/rwsize Sebastian Hesselbarth
2015-10-12 6:11 ` Sascha Hauer
2015-10-12 7:36 ` Sebastian Hesselbarth
2015-10-12 18:51 ` Sebastian Hesselbarth
2015-10-13 8:00 ` Sascha Hauer
2015-10-13 8:09 ` Sebastian Hesselbarth
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