Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Cong Wang <xiyou.wangcong@gmail.com>]

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On Thu, Oct 20, 2016 at 12:40 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Thu, Oct 20, 2016 at 12:32 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>>> From: Eric Dumazet <edumazet@google.com>
>>>
>>> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
>>> range") Cong added BH protection in set_local_port_range() but missed
>>> that same fix was needed in set_ping_group_range()
>>
>> Don't know why ping_group_range shares the same lock with local_port_range...
>> Perhaps just for saving a few bytes, but that is why I missed this place.
>
> Hold on... We clearly have typos there... Your fix is not correct.

We need the attached patch, your patch should be reverted, because
unlike local_port_range we never read it in BH context, no need to bother _bh.

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diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1cb67de..80bc36b 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -96,11 +96,11 @@ static void inet_get_ping_group_range_table(struct ctl_table *table, kgid_t *low
 		container_of(table->data, struct net, ipv4.ping_group_range.range);
 	unsigned int seq;
 	do {
-		seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
+		seq = read_seqbegin(&net->ipv4.ping_group_range.lock);
 
 		*low = data[0];
 		*high = data[1];
-	} while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
+	} while (read_seqretry(&net->ipv4.ping_group_range.lock, seq));
 }
 
 /* Update system visible IP port range */
@@ -109,10 +109,10 @@ static void set_ping_group_range(struct ctl_table *table, kgid_t low, kgid_t hig
 	kgid_t *data = table->data;
 	struct net *net =
 		container_of(table->data, struct net, ipv4.ping_group_range.range);
-	write_seqlock(&net->ipv4.ip_local_ports.lock);
+	write_seqlock(&net->ipv4.ping_group_range.lock);
 	data[0] = low;
 	data[1] = high;
-	write_sequnlock(&net->ipv4.ip_local_ports.lock);
+	write_sequnlock(&net->ipv4.ping_group_range.lock);
 }
 
 /* Validate changes from /proc interface. */