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From: Xin Long <lucien.xin@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: network dev <netdev@vger.kernel.org>,
	linux-sctp@vger.kernel.org,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	Vlad Yasevich <vyasevich@gmail.com>
Subject: Re: [PATCH net] sctp: check duplicate node before inserting a new transport
Date: Sat, 18 Feb 2017 23:47:38 +0800	[thread overview]
Message-ID: <CADvbK_dvJoEvmx1PvemxUS1090J1o=Gx3COPK7rdHT4Z1z27UQ@mail.gmail.com> (raw)
In-Reply-To: <20170217.151907.1987368624831286456.davem@davemloft.net>

On Sat, Feb 18, 2017 at 4:19 AM, David Miller <davem@davemloft.net> wrote:
> From: Xin Long <lucien.xin@gmail.com>
> Date: Fri, 17 Feb 2017 16:35:24 +0800
>
>
>> +     list = rhltable_lookup(&sctp_transport_hashtable, &arg,
>> +                            sctp_hash_params);
>> +
>> +     rhl_for_each_entry_rcu(transport, tmp, list, node)
>> +             if (transport->asoc->ep == t->asoc->ep) {
>> +                     err = -EEXIST;
>> +                     goto out;
>> +             }
>> +
>>       err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
>>                                 &t->node, sctp_hash_params);
>> +
>> +out:
>
> Well, what if another thread of control inserts a matching transport
> after you've checked the list but before rhltable_insert_key() does
> it's work?
>
> What write side lock is being held to protect the table from
> modifications here?
sock lock.
...
sctp_assoc_add_peer()
  sctp_hash_transport()
     rhltable_insert_key()

all the places where it call  sctp_assoc_add_peer() are proctected by
lock_sock(). it's a big lock, no need to worry about race issues here.

WARNING: multiple messages have this Message-ID (diff)
From: Xin Long <lucien.xin@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: network dev <netdev@vger.kernel.org>,
	linux-sctp@vger.kernel.org,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	Vlad Yasevich <vyasevich@gmail.com>
Subject: Re: [PATCH net] sctp: check duplicate node before inserting a new transport
Date: Sat, 18 Feb 2017 15:47:38 +0000	[thread overview]
Message-ID: <CADvbK_dvJoEvmx1PvemxUS1090J1o=Gx3COPK7rdHT4Z1z27UQ@mail.gmail.com> (raw)
In-Reply-To: <20170217.151907.1987368624831286456.davem@davemloft.net>

On Sat, Feb 18, 2017 at 4:19 AM, David Miller <davem@davemloft.net> wrote:
> From: Xin Long <lucien.xin@gmail.com>
> Date: Fri, 17 Feb 2017 16:35:24 +0800
>
>
>> +     list = rhltable_lookup(&sctp_transport_hashtable, &arg,
>> +                            sctp_hash_params);
>> +
>> +     rhl_for_each_entry_rcu(transport, tmp, list, node)
>> +             if (transport->asoc->ep = t->asoc->ep) {
>> +                     err = -EEXIST;
>> +                     goto out;
>> +             }
>> +
>>       err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
>>                                 &t->node, sctp_hash_params);
>> +
>> +out:
>
> Well, what if another thread of control inserts a matching transport
> after you've checked the list but before rhltable_insert_key() does
> it's work?
>
> What write side lock is being held to protect the table from
> modifications here?
sock lock.
...
sctp_assoc_add_peer()
  sctp_hash_transport()
     rhltable_insert_key()

all the places where it call  sctp_assoc_add_peer() are proctected by
lock_sock(). it's a big lock, no need to worry about race issues here.

  reply	other threads:[~2017-02-18 15:47 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-17  8:35 [PATCH net] sctp: check duplicate node before inserting a new transport Xin Long
2017-02-17  8:35 ` Xin Long
2017-02-17 11:19 ` Neil Horman
2017-02-17 11:19   ` Neil Horman
2017-02-17 14:32   ` Xin Long
2017-02-17 14:32     ` Xin Long
2017-02-17 20:19 ` David Miller
2017-02-17 20:19   ` David Miller
2017-02-18 15:47   ` Xin Long [this message]
2017-02-18 15:47     ` Xin Long
2017-02-19 23:19 ` David Miller
2017-02-19 23:19   ` David Miller

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