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From: Xin Long <lucien.xin@gmail.com>
To: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Vlad Yasevich <vyasevic@redhat.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	David Miller <davem@davemloft.net>,
	"linux-sctp@vger.kernel.org" <linux-sctp@vger.kernel.org>,
	Michael Tuexen <Michael.Tuexen@lurchi.franken.de>,
	Eric Dumazet <edumazet@google.com>,
	Brenda Butler <bjb@mojatatu.com>,
	gabor@mojatatu.com
Subject: Re: send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit
Date: Tue, 25 Oct 2016 17:05:41 +0800	[thread overview]
Message-ID: <CADvbK_eEaZBDXfY6D5dqRq3WRSgxvcHUxbq6JPnSrZ6Zpkghrw@mail.gmail.com> (raw)
In-Reply-To: <369b7b2c-d1fb-5dd2-30b9-4f54400aa770@mojatatu.com>

>> in case [1], user can't see the ENOMEM, ENOMEM is more like
>> a internal err.
>>
>
> Still not clear. Are you saying, say an old kernel like 3.11 would
> not return the user ENOMEN for the use case[1] you fixed? I am not
> talking post your fix.
Sorry for confusing you.

3.11 would return the user ENOMEN for the use case[1].
but this behavior is incorrect, it's not consistent with tcp.

>
>> in case [2], user will got the ENOMEM, they should resend this msg,
>> It's the the general case mentioned-above
>>
>
> I am trying to see if we can avoid backporting this fix to 3.11.
> In [1], is ENOMEM propagated to user space (dont talk about your
> fix, I mean pre-your-fix).
yes, in [1], pre-my-fix, ENOMEM is propagated to user space.

>
>
>> here sctp's behavior is actually same with tcp's, in tcp, tcp_transmit_skb
>> also may fail to alloc skb, but it doesn't return any err to user, just
>> like
>> sctp_packet_transmit. That's why I don't think we should change something
>> in manpage, as here sctp is consistent with tcp now.
>>
>> make sense ?
>
>
> No ;-> The manpage is bad. Go look at it. In the case of ENOBUFS or
> EMSGSIZE it is clear what needs to be done.
> If the answer is _on ENOMEM_ user must resend then thats what we need
> to say.
yes, on ENOMEM user must resend if he want send out this msg successfully.

WARNING: multiple messages have this Message-ID (diff)
From: Xin Long <lucien.xin@gmail.com>
To: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Vlad Yasevich <vyasevic@redhat.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	David Miller <davem@davemloft.net>,
	"linux-sctp@vger.kernel.org" <linux-sctp@vger.kernel.org>,
	Michael Tuexen <Michael.Tuexen@lurchi.franken.de>,
	Eric Dumazet <edumazet@google.com>,
	Brenda Butler <bjb@mojatatu.com>,
	gabor@mojatatu.com
Subject: Re: send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack
Date: Tue, 25 Oct 2016 09:05:41 +0000	[thread overview]
Message-ID: <CADvbK_eEaZBDXfY6D5dqRq3WRSgxvcHUxbq6JPnSrZ6Zpkghrw@mail.gmail.com> (raw)
In-Reply-To: <369b7b2c-d1fb-5dd2-30b9-4f54400aa770@mojatatu.com>

>> in case [1], user can't see the ENOMEM, ENOMEM is more like
>> a internal err.
>>
>
> Still not clear. Are you saying, say an old kernel like 3.11 would
> not return the user ENOMEN for the use case[1] you fixed? I am not
> talking post your fix.
Sorry for confusing you.

3.11 would return the user ENOMEN for the use case[1].
but this behavior is incorrect, it's not consistent with tcp.

>
>> in case [2], user will got the ENOMEM, they should resend this msg,
>> It's the the general case mentioned-above
>>
>
> I am trying to see if we can avoid backporting this fix to 3.11.
> In [1], is ENOMEM propagated to user space (dont talk about your
> fix, I mean pre-your-fix).
yes, in [1], pre-my-fix, ENOMEM is propagated to user space.

>
>
>> here sctp's behavior is actually same with tcp's, in tcp, tcp_transmit_skb
>> also may fail to alloc skb, but it doesn't return any err to user, just
>> like
>> sctp_packet_transmit. That's why I don't think we should change something
>> in manpage, as here sctp is consistent with tcp now.
>>
>> make sense ?
>
>
> No ;-> The manpage is bad. Go look at it. In the case of ENOBUFS or
> EMSGSIZE it is clear what needs to be done.
> If the answer is _on ENOMEM_ user must resend then thats what we need
> to say.
yes, on ENOMEM user must resend if he want send out this msg successfully.

  reply	other threads:[~2016-10-25  9:05 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-23 15:03 send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_t Jamal Hadi Salim
2016-10-23 15:32 ` Fwd: send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Jamal Hadi Salim
2016-10-23 15:32   ` Fwd: send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pac Jamal Hadi Salim
2016-10-23 18:20   ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Xin Long
2016-10-23 18:20     ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Xin Long
2016-10-23 19:52     ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Jamal Hadi Salim
2016-10-23 19:52       ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Jamal Hadi Salim
2016-10-24  6:30       ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Xin Long
2016-10-24  6:30         ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Xin Long
2016-10-24 11:48         ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Marcelo Ricardo Leitner
2016-10-24 11:48           ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Marcelo Ricardo Leitner
2016-10-24 12:38         ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Jamal Hadi Salim
2016-10-24 12:38           ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Jamal Hadi Salim
2016-10-25  9:05           ` Xin Long [this message]
2016-10-25  9:05             ` Xin Long
2016-10-25 10:34             ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Marcelo Ricardo Leitner
2016-10-25 10:34               ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Marcelo Ricardo Leitner
2016-10-25 11:04               ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_packet_transmit Jamal Hadi Salim
2016-10-25 11:04                 ` send/sendmsg ENOMEM errors WAS(Re: [PATCH net 6/6] sctp: not return ENOMEM err back in sctp_pack Jamal Hadi Salim

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