[net-next,v5,2/3] sysctl: add proc_do_large_bitmap

On Monday 22 February 2010 04:45:44 you wrote:
> Octavian Purdila wrote:
> > But I think its worth to keep the whitespaces in beetween, e.g. allow
> >
> > $ echo '1, 2 ,3 ' >   ip_local_reserved_ports.
> 
> Sure.
> 
> >> Also, if I write an invalid value, it does reject this, but the previous
> >> value in that file is cleared, shouldn't we keep the previous one?
> >
> > The only way I see to fix this is to return EINVAL if we detect a write
> > with offset.
> 
> Yeah, we shouldn't continue once we find any invalid value.
> 
> > IMO we should do that for the other proc write routines as well, as
> > otherwise ther result is confusing, e.g.
> >
> > write("1 2"); write(" 3");
> >
> > will set first value in the vector to 1, than second value to 2 then
> > *first* value to 3.
> >
> > I am all for it, but again, this changes userspace ABI.
> 
> Sorry, is this related with the problem I mentioned above? Both "1 2"
> and " 3" are valid values.
> 

Never mind, please disregard my "return EINVAL if we detect a write
with offset", it breaks the ABI in a significant way.

Here is a new version of this patch which fixes both the comma and invalid 
value issues, please give it a try.

[net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap

The new function can be used to read/write large bitmaps via /proc. A
comma separated range format is used for compact output and input
(e.g. 1,3-4,10-10).

Writing into the file will first reset the bitmap then update it
based on the given input.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Cc: WANG Cong <amwang@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
---
 include/linux/sysctl.h |    2 +
 kernel/sysctl.c        |  134 
++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+), 0 deletions(-)

 int proc_dostring(struct ctl_table *table, int write,

Octavian Purdila wrote:
> 
> Here is a new version of this patch which fixes both the comma and invalid 
> value issues, please give it a try.
> 

Sorry, it is even worse. :(

> [net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap
> 
> The new function can be used to read/write large bitmaps via /proc. A
> comma separated range format is used for compact output and input
> (e.g. 1,3-4,10-10).
> 


Writing "50000-50100" gets EINVAL, it should be success.
Writing "50000,50100" fails too.

Please, at least, do some basic testing.

Also some comments below.

> Writing into the file will first reset the bitmap then update it
> based on the given input.
> 
> Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
> Cc: WANG Cong <amwang@redhat.com>
> Cc: Eric W. Biederman <ebiederm@xmission.com>

Please resend the whole patchset, and update the doc in patch 3/3.


> ---
>  include/linux/sysctl.h |    2 +
>  kernel/sysctl.c        |  134 
> ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 136 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index f66014c..7bb5cb6 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -980,6 +980,8 @@ extern int proc_doulongvec_minmax(struct ctl_table *, int,
>  				  void __user *, size_t *, loff_t *);
>  extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
>  				      void __user *, size_t *, loff_t *);
> +extern int proc_do_large_bitmap(struct ctl_table *, int,
> +				void __user *, size_t *, loff_t *);
>  
>  /*
>   * Register a set of sysctl names by calling register_sysctl_table
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 5259727..d8ea839 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2635,6 +2635,140 @@ static int proc_do_cad_pid(struct ctl_table *table, 
> int write,


The above line is wrong, it should be a part of previous line.


>  	return 0;
>  }
>  
> +/**
> + * proc_do_large_bitmap - read/write from/to a large bitmap
> + * @table: the sysctl table
> + * @write: %TRUE if this is a write to the sysctl file
> + * @buffer: the user buffer
> + * @lenp: the size of the user buffer
> + * @ppos: file position
> + *
> + * The bitmap is stored at table->data and the bitmap length (in bits)
> + * in table->maxlen.
> + *
> + * We use a range comma separated format (e.g. 1,3-4,10-10) so that
> + * large bitmaps may be represented in a compact manner. Writing into
> + * the file will clear the bitmap then update it with the given input.
> + *
> + * Returns 0 on success.
> + */
> +int proc_do_large_bitmap(struct ctl_table *table, int write,
> +			 void __user *_buffer, size_t *lenp, loff_t *ppos)
> +{
> +	bool first = 1;
> +	unsigned long *bitmap = (unsigned long *) table->data;
> +	unsigned long bitmap_len = table->maxlen;
> +	int left = *lenp, err = 0;


'left' should be size_t.


> +	char __user *buffer = (char __user *) _buffer;
> +	char tr_a[] = { '-', ',', 0 }, tr_b[] = { ',', 0 }, c;
> +
> +
> +	if (!bitmap_len || !left || (*ppos && !write)) {
> +		*lenp = 0;
> +		return 0;
> +	}
> +
> +	if (write) {
> +		err = proc_skip_wspace(&buffer, &left);
> +		while (!err && left) {
> +			unsigned long val_a, val_b;
> +			bool neg;
> +
> +			err = proc_get_ulong(&buffer, &left, tr_a,
> +					     &val_a, &neg, &c);
> +			if (err)
> +				break;
> +
> +			if (val_a >= bitmap_len || neg) {
> +				err = -EINVAL;
> +				break;
> +			}
> +
> +			val_b = val_a;
> +			if (left && c == '-') {
> +				/* skip the - */
> +				buffer++; left--;
> +
> +				err = proc_get_ulong(&buffer, &left, tr_b,
> +						     &val_b, &neg, &c);
> +				if (err)
> +					break;
> +
> +				if (val_b >= bitmap_len || neg ||
> +				    val_a > val_b) {
> +					err = -EINVAL;
> +					break;
> +				}
> +			}
> +
> +			if (left) {
> +				err = proc_skip_wspace(&buffer, &left);
> +				if (err)
> +					break;
> +				if (left) {
> +					if (get_user(c, buffer)) {
> +						err = -EFAULT;
> +						break;
> +					}
> +					if (c != ',') {
> +						err = -EINVAL;
> +						break;
> +					}
> +					/* skip the , */
> +					buffer++; left--;
> +				}
> +			}
> +
> +			if (first)
> +				bitmap_clear(bitmap, 0, bitmap_len);
> +
> +			while (val_a <= val_b)
> +				set_bit(val_a++, bitmap);
> +
> +			first = 0;
> +		}
> +		if (!err)
> +			err = proc_skip_wspace(&buffer, &left);
> +	} else {
> +		unsigned long bit_a, bit_b = 0;
> +
> +		while (left) {
> +			bit_a = find_next_bit(bitmap, bitmap_len, bit_b);
> +			if (bit_a >= bitmap_len)
> +				break;
> +			bit_b = find_next_zero_bit(bitmap, bitmap_len,
> +						   bit_a + 1) - 1;
> +
> +			err = proc_put_ulong(&buffer, &left, bit_a, 0, first,
> +					     ',');
> +			if (err)
> +				break;
> +			if (bit_a != bit_b) {
> +				err = proc_put_char(&buffer, &left, '-');
> +				if (err)
> +					break;
> +				err = proc_put_ulong(&buffer, &left, bit_b, 0,
> +						     1, 0);
> +				if (err)
> +					break;
> +			}
> +
> +			first = 0; bit_b++;
> +		}
> +		if (!err)
> +			err = proc_put_char(&buffer, &left, '\n');
> +	}
> +
> +	if (first) {
> +		if (err)
> +			return err;
> +		bitmap_clear(bitmap, 0, bitmap_len);
> +	}
> +	*lenp -= left;
> +	*ppos += *lenp;
> +	return 0;
> +}
> +
>  #else /* CONFIG_PROC_FS */
>  
>  int proc_dostring(struct ctl_table *table, int write,

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Cong Wang wrote:
>> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>> index 5259727..d8ea839 100644
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -2635,6 +2635,140 @@ static int proc_do_cad_pid(struct ctl_table 
>> *table, int write,
> 
> 
> The above line is wrong, it should be a part of previous line.
> 
> 

Sorry, ignore this, it should be my thunderbird's fault,
it truncated the line. I will fix it...
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On Wednesday 24 February 2010 07:24:00 you wrote:
> Octavian Purdila wrote:
> > Here is a new version of this patch which fixes both the comma and
> > invalid value issues, please give it a try.
> 
> Sorry, it is even worse. :(
> 
> > [net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap
> >
> > The new function can be used to read/write large bitmaps via /proc. A
> > comma separated range format is used for compact output and input
> > (e.g. 1,3-4,10-10).
> 
> Writing "50000-50100" gets EINVAL, it should be success.
> Writing "50000,50100" fails too.
> 

Hmm, they don't fail for me :-/

> Please, at least, do some basic testing.
> 

I do test them, I've attached the current test batch I was using.

Anyways, today I've noticed that "1,2 3" does not fail and even more 
importantly the final value is "3". 

Being that I don't see a way of fixing this without not acknowledging 1,2 even 
though we will do set these values, I revisited the "1 2 3" issue. And I don't 
understand why this is actually an issue, we are just being more permissive 
(i.e. we are allowing as separators both whitespaces and ,).


> Also some comments below.
> 
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index 5259727..d8ea839 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -2635,6 +2635,140 @@ static int proc_do_cad_pid(struct ctl_table
> > *table, int write,
> 
> The above line is wrong, it should be a part of previous line.
> 

Probably my email client corrupted the patch, sorry about that, I will be more 
careful next time.

> > +	int left = *lenp, err = 0;
> 
> 'left' should be size_t.
> 

Will fix, thanks for catching this.

I will resend the whole patch series once we get this formatting issue 
resolved.

Octavian Purdila wrote:
> On Wednesday 24 February 2010 07:24:00 you wrote:
>> Octavian Purdila wrote:
>>> Here is a new version of this patch which fixes both the comma and
>>> invalid value issues, please give it a try.
>> Sorry, it is even worse. :(
>>
>>> [net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap
>>>
>>> The new function can be used to read/write large bitmaps via /proc. A
>>> comma separated range format is used for compact output and input
>>> (e.g. 1,3-4,10-10).
>> Writing "50000-50100" gets EINVAL, it should be success.
>> Writing "50000,50100" fails too.
>>
> 
> Hmm, they don't fail for me :-/
> 
>> Please, at least, do some basic testing.
>>
> 
> I do test them, I've attached the current test batch I was using.
> 
> Anyways, today I've noticed that "1,2 3" does not fail and even more 
> importantly the final value is "3". 
> 
> Being that I don't see a way of fixing this without not acknowledging 1,2 even 
> though we will do set these values, I revisited the "1 2 3" issue. And I don't 
> understand why this is actually an issue, we are just being more permissive 
> (i.e. we are allowing as separators both whitespaces and ,).
> 
> 

Oops, after rechecking my test case, it is actually my test case's
fault. Sorry for this. I will fix my test case and run it again.


> 
> I will resend the whole patch series once we get this formatting issue 
> resolved.
> 

Thanks much!
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Cong Wang wrote:
> Octavian Purdila wrote:
>> On Wednesday 24 February 2010 07:24:00 you wrote:
>>> Octavian Purdila wrote:
>>>> Here is a new version of this patch which fixes both the comma and
>>>> invalid value issues, please give it a try.
>>> Sorry, it is even worse. :(
>>>
>>>> [net-next PATCH v5 2/3] sysctl: add proc_do_large_bitmap
>>>>
>>>> The new function can be used to read/write large bitmaps via /proc. A
>>>> comma separated range format is used for compact output and input
>>>> (e.g. 1,3-4,10-10).
>>> Writing "50000-50100" gets EINVAL, it should be success.
>>> Writing "50000,50100" fails too.
>>>
>>
>> Hmm, they don't fail for me :-/
>>
>>> Please, at least, do some basic testing.
>>>
>>
>> I do test them, I've attached the current test batch I was using.
>>
>> Anyways, today I've noticed that "1,2 3" does not fail and even more 
>> importantly the final value is "3".
>> Being that I don't see a way of fixing this without not acknowledging 
>> 1,2 even though we will do set these values, I revisited the "1 2 3" 
>> issue. And I don't understand why this is actually an issue, we are 
>> just being more permissive (i.e. we are allowing as separators both 
>> whitespaces and ,).
>>
>>
> 
> Oops, after rechecking my test case, it is actually my test case's
> fault. Sorry for this. I will fix my test case and run it again.
> 

Hi,

Still a small problem, if I do write(fd, "50000,50100", 12) I will
get a return value of 11, which should mean 11 bytes are written,
however, actually only the first 6 bytes are accepted.

The rest looks better now.

Or am I missing something here? :)

Thanks!
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