Patchwork [net-next,5/6] bonding: restructure and simplify bond_for_each_slave_next()

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Submitter dingtianhong
Date Aug. 30, 2013, 10:05 a.m.
Message ID <52206E4E.6010507@huawei.com>
Download mbox | patch
Permalink /patch/271209/
State Changes Requested
Delegated to: David Miller
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Comments

dingtianhong - Aug. 30, 2013, 10:05 a.m.
remove the wordy int and add bond_for_each_slave_next_rcu() for future use.

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Cc: Nikolay Aleksandrov <nikolay@redhat.com>
---
 drivers/net/bonding/bond_alb.c  |  3 +--
 drivers/net/bonding/bond_main.c |  6 ++----
 drivers/net/bonding/bonding.h   | 19 +++++++++++++++----
 3 files changed, 18 insertions(+), 10 deletions(-)
Nikolay Aleksandrov - Sept. 3, 2013, 10:22 a.m.
On 08/30/2013 12:05 PM, Ding Tianhong wrote:
> remove the wordy int and add bond_for_each_slave_next_rcu() for future use.
> 
> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
> Cc: Nikolay Aleksandrov <nikolay@redhat.com>
> ---
>  drivers/net/bonding/bond_alb.c  |  3 +--
>  drivers/net/bonding/bond_main.c |  6 ++----
>  drivers/net/bonding/bonding.h   | 19 +++++++++++++++----
>  3 files changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
> index 3a5db7b..d266c56 100644
> --- a/drivers/net/bonding/bond_alb.c
> +++ b/drivers/net/bonding/bond_alb.c
> @@ -383,7 +383,6 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond)
>  {
>  	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
>  	struct slave *rx_slave, *slave, *start_at;
> -	int i = 0;
>  
>  	if (bond_info->next_rx_slave)
>  		start_at = bond_info->next_rx_slave;
> @@ -392,7 +391,7 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond)
>  
>  	rx_slave = NULL;
>  
> -	bond_for_each_slave_from(bond, slave, i, start_at) {
> +	bond_for_each_slave_from(bond, slave, start_at) {
>  		if (SLAVE_IS_OK(slave)) {
>  			if (!rx_slave) {
>  				rx_slave = slave;
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 4264a76..8c9902a 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -904,7 +904,6 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
>  	struct slave *new_active, *old_active;
>  	struct slave *bestslave = NULL;
>  	int mintime = bond->params.updelay;
> -	int i;
>  
>  	new_active = bond->curr_active_slave;
>  
> @@ -923,7 +922,7 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
>  	/* remember where to stop iterating over the slaves */
>  	old_active = new_active;
>  
> -	bond_for_each_slave_from(bond, new_active, i, old_active) {
> +	bond_for_each_slave_from(bond, new_active, old_active) {
>  		if (new_active->link == BOND_LINK_UP) {
>  			return new_active;
>  		} else if (new_active->link == BOND_LINK_BACK &&
> @@ -2891,7 +2890,6 @@ do_failover:
>  static void bond_ab_arp_probe(struct bonding *bond)
>  {
>  	struct slave *slave, *next_slave;
> -	int i;
>  
>  	read_lock(&bond->curr_slave_lock);
>  
> @@ -2923,7 +2921,7 @@ static void bond_ab_arp_probe(struct bonding *bond)
>  
>  	/* search for next candidate */
>  	next_slave = bond_next_slave(bond, bond->current_arp_slave);
> -	bond_for_each_slave_from(bond, slave, i, next_slave) {
> +	bond_for_each_slave_from(bond, slave, next_slave) {
>  		if (IS_UP(slave->dev)) {
>  			slave->link = BOND_LINK_BACK;
>  			bond_set_slave_active_flags(slave);
> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
> index 9898493..a3ab47f 100644
> --- a/drivers/net/bonding/bonding.h
> +++ b/drivers/net/bonding/bonding.h
> @@ -119,14 +119,25 @@
>   * bond_for_each_slave_from - iterate the slaves list from a starting point
>   * @bond:	the bond holding this list.
>   * @pos:	current slave.
> - * @cnt:	counter for max number of moves
>   * @start:	starting point.
>   *
>   * Caller must hold bond->lock
>   */
> -#define bond_for_each_slave_from(bond, pos, cnt, start) \
> -	for (cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
> -	     cnt++, pos = bond_next_slave(bond, pos))
> +#define bond_for_each_slave_from(bond, pos, start) \
> +	for (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
> +	    cnt++, pos = bond_next_slave(bond, pos))
> +
Please read below the argument against using the nested cnt definition.

> +/**
> + * bond_for_each_slave_from_rcu - iterate the slaves list from a starting point
> + * @bond:	the bond holding this list.
> + * @pos:	current slave.
> + * @start:	starting point.
> + *
> + * Caller must hold rcu_read_lock
> + */
> +#define bond_for_each_slave_from_rcu(bond, pos, start) \
> +	for (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
> +	    cnt++, pos = bond_next_slave_rcu(bond, pos))
>  
I don't think you can rely on slave_cnt in RCU, you may go overboard and pass
twice over the same slave if a slave gets removed, or the opposite. Also this
definition of cnt is troublesome because the name is quite common, I don't know
if it's accepted, but it if it is at least change the name to something like
__cnt or anything that is less likely to be defined.
The cnt argument goes for bond_for_each_slave_from as well.

>  /**
>   * bond_for_each_slave - iterate over all slaves
> 

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dingtianhong - Sept. 4, 2013, 6:23 a.m.
On 2013/9/3 18:22, Nikolay Aleksandrov wrote:
> On 08/30/2013 12:05 PM, Ding Tianhong wrote:
>> remove the wordy int and add bond_for_each_slave_next_rcu() for future use.
>>
>> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
>> Cc: Nikolay Aleksandrov <nikolay@redhat.com>
>> ---
>>  drivers/net/bonding/bond_alb.c  |  3 +--
>>  drivers/net/bonding/bond_main.c |  6 ++----
>>  drivers/net/bonding/bonding.h   | 19 +++++++++++++++----
>>  3 files changed, 18 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
>> index 3a5db7b..d266c56 100644
>> --- a/drivers/net/bonding/bond_alb.c
>> +++ b/drivers/net/bonding/bond_alb.c
>> @@ -383,7 +383,6 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond)
>>  {
>>  	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
>>  	struct slave *rx_slave, *slave, *start_at;
>> -	int i = 0;
>>  
>>  	if (bond_info->next_rx_slave)
>>  		start_at = bond_info->next_rx_slave;
>> @@ -392,7 +391,7 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond)
>>  
>>  	rx_slave = NULL;
>>  
>> -	bond_for_each_slave_from(bond, slave, i, start_at) {
>> +	bond_for_each_slave_from(bond, slave, start_at) {
>>  		if (SLAVE_IS_OK(slave)) {
>>  			if (!rx_slave) {
>>  				rx_slave = slave;
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 4264a76..8c9902a 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -904,7 +904,6 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
>>  	struct slave *new_active, *old_active;
>>  	struct slave *bestslave = NULL;
>>  	int mintime = bond->params.updelay;
>> -	int i;
>>  
>>  	new_active = bond->curr_active_slave;
>>  
>> @@ -923,7 +922,7 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
>>  	/* remember where to stop iterating over the slaves */
>>  	old_active = new_active;
>>  
>> -	bond_for_each_slave_from(bond, new_active, i, old_active) {
>> +	bond_for_each_slave_from(bond, new_active, old_active) {
>>  		if (new_active->link == BOND_LINK_UP) {
>>  			return new_active;
>>  		} else if (new_active->link == BOND_LINK_BACK &&
>> @@ -2891,7 +2890,6 @@ do_failover:
>>  static void bond_ab_arp_probe(struct bonding *bond)
>>  {
>>  	struct slave *slave, *next_slave;
>> -	int i;
>>  
>>  	read_lock(&bond->curr_slave_lock);
>>  
>> @@ -2923,7 +2921,7 @@ static void bond_ab_arp_probe(struct bonding *bond)
>>  
>>  	/* search for next candidate */
>>  	next_slave = bond_next_slave(bond, bond->current_arp_slave);
>> -	bond_for_each_slave_from(bond, slave, i, next_slave) {
>> +	bond_for_each_slave_from(bond, slave, next_slave) {
>>  		if (IS_UP(slave->dev)) {
>>  			slave->link = BOND_LINK_BACK;
>>  			bond_set_slave_active_flags(slave);
>> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
>> index 9898493..a3ab47f 100644
>> --- a/drivers/net/bonding/bonding.h
>> +++ b/drivers/net/bonding/bonding.h
>> @@ -119,14 +119,25 @@
>>   * bond_for_each_slave_from - iterate the slaves list from a starting point
>>   * @bond:	the bond holding this list.
>>   * @pos:	current slave.
>> - * @cnt:	counter for max number of moves
>>   * @start:	starting point.
>>   *
>>   * Caller must hold bond->lock
>>   */
>> -#define bond_for_each_slave_from(bond, pos, cnt, start) \
>> -	for (cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
>> -	     cnt++, pos = bond_next_slave(bond, pos))
>> +#define bond_for_each_slave_from(bond, pos, start) \
>> +	for (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
>> +	    cnt++, pos = bond_next_slave(bond, pos))
>> +
> Please read below the argument against using the nested cnt definition.
> 
>> +/**
>> + * bond_for_each_slave_from_rcu - iterate the slaves list from a starting point
>> + * @bond:	the bond holding this list.
>> + * @pos:	current slave.
>> + * @start:	starting point.
>> + *
>> + * Caller must hold rcu_read_lock
>> + */
>> +#define bond_for_each_slave_from_rcu(bond, pos, start) \
>> +	for (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
>> +	    cnt++, pos = bond_next_slave_rcu(bond, pos))
>>  
> I don't think you can rely on slave_cnt in RCU, you may go overboard and pass
> twice over the same slave if a slave gets removed, or the opposite. Also this
> definition of cnt is troublesome because the name is quite common, I don't know
> if it's accepted, but it if it is at least change the name to something like
> __cnt or anything that is less likely to be defined.
> The cnt argument goes for bond_for_each_slave_from as well.
> 

yes, more details need to think about, I modify the function to this:

#define bond_for_each_slave_from(bond, pos, start) \
        for (pos = start; (pos == bond_next_slave(bond, start) ? \
                    &pos->list != &bond->slave_list : \
                    &pos->list != &start->list); \
                    pos = bond_next_slave(bond, pos))

I think it is fine here, or I miss something, please tell me, thanks. :)

>>  /**
>>   * bond_for_each_slave - iterate over all slaves
>>
> 
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> 
> .
> 


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Patch

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 3a5db7b..d266c56 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -383,7 +383,6 @@  static struct slave *rlb_next_rx_slave(struct bonding *bond)
 {
 	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
 	struct slave *rx_slave, *slave, *start_at;
-	int i = 0;
 
 	if (bond_info->next_rx_slave)
 		start_at = bond_info->next_rx_slave;
@@ -392,7 +391,7 @@  static struct slave *rlb_next_rx_slave(struct bonding *bond)
 
 	rx_slave = NULL;
 
-	bond_for_each_slave_from(bond, slave, i, start_at) {
+	bond_for_each_slave_from(bond, slave, start_at) {
 		if (SLAVE_IS_OK(slave)) {
 			if (!rx_slave) {
 				rx_slave = slave;
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 4264a76..8c9902a 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -904,7 +904,6 @@  static struct slave *bond_find_best_slave(struct bonding *bond)
 	struct slave *new_active, *old_active;
 	struct slave *bestslave = NULL;
 	int mintime = bond->params.updelay;
-	int i;
 
 	new_active = bond->curr_active_slave;
 
@@ -923,7 +922,7 @@  static struct slave *bond_find_best_slave(struct bonding *bond)
 	/* remember where to stop iterating over the slaves */
 	old_active = new_active;
 
-	bond_for_each_slave_from(bond, new_active, i, old_active) {
+	bond_for_each_slave_from(bond, new_active, old_active) {
 		if (new_active->link == BOND_LINK_UP) {
 			return new_active;
 		} else if (new_active->link == BOND_LINK_BACK &&
@@ -2891,7 +2890,6 @@  do_failover:
 static void bond_ab_arp_probe(struct bonding *bond)
 {
 	struct slave *slave, *next_slave;
-	int i;
 
 	read_lock(&bond->curr_slave_lock);
 
@@ -2923,7 +2921,7 @@  static void bond_ab_arp_probe(struct bonding *bond)
 
 	/* search for next candidate */
 	next_slave = bond_next_slave(bond, bond->current_arp_slave);
-	bond_for_each_slave_from(bond, slave, i, next_slave) {
+	bond_for_each_slave_from(bond, slave, next_slave) {
 		if (IS_UP(slave->dev)) {
 			slave->link = BOND_LINK_BACK;
 			bond_set_slave_active_flags(slave);
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 9898493..a3ab47f 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -119,14 +119,25 @@ 
  * bond_for_each_slave_from - iterate the slaves list from a starting point
  * @bond:	the bond holding this list.
  * @pos:	current slave.
- * @cnt:	counter for max number of moves
  * @start:	starting point.
  *
  * Caller must hold bond->lock
  */
-#define bond_for_each_slave_from(bond, pos, cnt, start) \
-	for (cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
-	     cnt++, pos = bond_next_slave(bond, pos))
+#define bond_for_each_slave_from(bond, pos, start) \
+	for (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
+	    cnt++, pos = bond_next_slave(bond, pos))
+
+/**
+ * bond_for_each_slave_from_rcu - iterate the slaves list from a starting point
+ * @bond:	the bond holding this list.
+ * @pos:	current slave.
+ * @start:	starting point.
+ *
+ * Caller must hold rcu_read_lock
+ */
+#define bond_for_each_slave_from_rcu(bond, pos, start) \
+	for (int cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
+	    cnt++, pos = bond_next_slave_rcu(bond, pos))
 
 /**
  * bond_for_each_slave - iterate over all slaves