[PATCH] bonding: cleanup bond_opts array

[PATCH] bonding: cleanup bond_opts array

[Jonathan Toppins]

Remove the empty array element initializer and size the array with
BOND_OPT_LAST so the compiler will complain if more elements are in
there than should be.

An interesting unwanted side effect of this initializer is that if one
inserts new options into the middle of the array then this initializer
will zero out the option that equals BOND_OPT_TLB_DYNAMIC_LB+1.

Example:
Extend the OPTS enum:
enum {
   ...
   BOND_OPT_TLB_DYNAMIC_LB,
   BOND_OPT_LACP_NEW1,
   BOND_OPT_LAST
};

Now insert into bond_opts array:
static const struct bond_option bond_opts[] = {
      ...
      [BOND_OPT_LACP_RATE] = { .... unchanged stuff .... },
      [BOND_OPT_LACP_NEW1] = { ... new stuff ... },
      ...
      [BOND_OPT_TLB_DYNAMIC_LB] = { .... unchanged stuff ....},
      { } // MARK A
};

Since BOND_OPT_LACP_NEW1 = BOND_OPT_TLB_DYNAMIC_LB+1, the last
initializer (MARK A) will overwrite the contents of BOND_OPT_LACP_NEW1
and can be easily viewed with the crash utility.

Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
Cc: Andy Gospodarek <gospo@cumulusnetworks.com>
Cc: Nikolay Aleksandrov <nikolay@redhat.com>
---
 drivers/net/bonding/bond_options.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index 1a61cc9..9bd538d4 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -186,7 +186,7 @@ static const struct bond_opt_value bond_tlb_dynamic_lb_tbl[] = {
 	{ NULL,  -1, 0}
 };
 
-static const struct bond_option bond_opts[] = {
+static const struct bond_option bond_opts[BOND_OPT_LAST] = {
 	[BOND_OPT_MODE] = {
 		.id = BOND_OPT_MODE,
 		.name = "mode",
@@ -379,8 +379,7 @@ static const struct bond_option bond_opts[] = {
 		.values = bond_tlb_dynamic_lb_tbl,
 		.flags = BOND_OPTFLAG_IFDOWN,
 		.set = bond_option_tlb_dynamic_lb_set,
-	},
-	{ }
+	}
 };
 
 /* Searches for an option by name */
-- 
1.7.10.4

Re: [PATCH] bonding: cleanup bond_opts array

[Andy Gospodarek]

On Fri, Jan 09, 2015 at 01:31:08PM -0500, Jonathan Toppins wrote:
> Remove the empty array element initializer and size the array with
> BOND_OPT_LAST so the compiler will complain if more elements are in
> there than should be.
> 
> An interesting unwanted side effect of this initializer is that if one
> inserts new options into the middle of the array then this initializer
> will zero out the option that equals BOND_OPT_TLB_DYNAMIC_LB+1.
> 
> Example:
> Extend the OPTS enum:
> enum {
>    ...
>    BOND_OPT_TLB_DYNAMIC_LB,
>    BOND_OPT_LACP_NEW1,
>    BOND_OPT_LAST
> };
> 
> Now insert into bond_opts array:
> static const struct bond_option bond_opts[] = {
>       ...
>       [BOND_OPT_LACP_RATE] = { .... unchanged stuff .... },
>       [BOND_OPT_LACP_NEW1] = { ... new stuff ... },
>       ...
>       [BOND_OPT_TLB_DYNAMIC_LB] = { .... unchanged stuff ....},
>       { } // MARK A
> };
> 
> Since BOND_OPT_LACP_NEW1 = BOND_OPT_TLB_DYNAMIC_LB+1, the last
> initializer (MARK A) will overwrite the contents of BOND_OPT_LACP_NEW1
> and can be easily viewed with the crash utility.
> 
> Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
> Cc: Andy Gospodarek <gospo@cumulusnetworks.com>
> Cc: Nikolay Aleksandrov <nikolay@redhat.com>

I do not recall if there was a specific reason that Nik added this, so
presuming there was not....

Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>

> ---
>  drivers/net/bonding/bond_options.c |    5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
> index 1a61cc9..9bd538d4 100644
> --- a/drivers/net/bonding/bond_options.c
> +++ b/drivers/net/bonding/bond_options.c
> @@ -186,7 +186,7 @@ static const struct bond_opt_value bond_tlb_dynamic_lb_tbl[] = {
>  	{ NULL,  -1, 0}
>  };
>  
> -static const struct bond_option bond_opts[] = {
> +static const struct bond_option bond_opts[BOND_OPT_LAST] = {
>  	[BOND_OPT_MODE] = {
>  		.id = BOND_OPT_MODE,
>  		.name = "mode",
> @@ -379,8 +379,7 @@ static const struct bond_option bond_opts[] = {
>  		.values = bond_tlb_dynamic_lb_tbl,
>  		.flags = BOND_OPTFLAG_IFDOWN,
>  		.set = bond_option_tlb_dynamic_lb_set,
> -	},
> -	{ }
> +	}
>  };
>  
>  /* Searches for an option by name */
> -- 
> 1.7.10.4
> 

Re: [PATCH] bonding: cleanup bond_opts array

[Nikolay Aleksandrov]

On 09/01/15 19:48, Andy Gospodarek wrote:
> On Fri, Jan 09, 2015 at 01:31:08PM -0500, Jonathan Toppins wrote:
>> Remove the empty array element initializer and size the array with
>> BOND_OPT_LAST so the compiler will complain if more elements are in
>> there than should be.
>>
>> An interesting unwanted side effect of this initializer is that if one
>> inserts new options into the middle of the array then this initializer
>> will zero out the option that equals BOND_OPT_TLB_DYNAMIC_LB+1.
>>
>> Example:
>> Extend the OPTS enum:
>> enum {
>>    ...
>>    BOND_OPT_TLB_DYNAMIC_LB,
>>    BOND_OPT_LACP_NEW1,
>>    BOND_OPT_LAST
>> };
>>
>> Now insert into bond_opts array:
>> static const struct bond_option bond_opts[] = {
>>       ...
>>       [BOND_OPT_LACP_RATE] = { .... unchanged stuff .... },
>>       [BOND_OPT_LACP_NEW1] = { ... new stuff ... },
>>       ...
>>       [BOND_OPT_TLB_DYNAMIC_LB] = { .... unchanged stuff ....},
>>       { } // MARK A
>> };
>>
>> Since BOND_OPT_LACP_NEW1 = BOND_OPT_TLB_DYNAMIC_LB+1, the last
>> initializer (MARK A) will overwrite the contents of BOND_OPT_LACP_NEW1
>> and can be easily viewed with the crash utility.
>>
>> Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
>> Cc: Andy Gospodarek <gospo@cumulusnetworks.com>
>> Cc: Nikolay Aleksandrov <nikolay@redhat.com>
> 
> I do not recall if there was a specific reason that Nik added this, so
> presuming there was not....
> 
> Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
> 
Indeed, it's an oversight on my part from a previous version of the opts
patch-set which used a different end-of-array indicator :-)


Acked-by: Nikolay Aleksandrov <nikolay@redhat.com>

Re: [PATCH] bonding: cleanup bond_opts array

[David Miller]

From: Jonathan Toppins <jtoppins@cumulusnetworks.com>
Date: Fri,  9 Jan 2015 13:31:08 -0500

> Remove the empty array element initializer and size the array with
> BOND_OPT_LAST so the compiler will complain if more elements are in
> there than should be.
> 
> An interesting unwanted side effect of this initializer is that if one
> inserts new options into the middle of the array then this initializer
> will zero out the option that equals BOND_OPT_TLB_DYNAMIC_LB+1.
> 
> Example:
> Extend the OPTS enum:
> enum {
>    ...
>    BOND_OPT_TLB_DYNAMIC_LB,
>    BOND_OPT_LACP_NEW1,
>    BOND_OPT_LAST
> };
> 
> Now insert into bond_opts array:
> static const struct bond_option bond_opts[] = {
>       ...
>       [BOND_OPT_LACP_RATE] = { .... unchanged stuff .... },
>       [BOND_OPT_LACP_NEW1] = { ... new stuff ... },
>       ...
>       [BOND_OPT_TLB_DYNAMIC_LB] = { .... unchanged stuff ....},
>       { } // MARK A
> };
> 
> Since BOND_OPT_LACP_NEW1 = BOND_OPT_TLB_DYNAMIC_LB+1, the last
> initializer (MARK A) will overwrite the contents of BOND_OPT_LACP_NEW1
> and can be easily viewed with the crash utility.
> 
> Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>

Applied.