From: Manfred Spraul <manfred@colorfullife.com>
To: Davidlohr Bueso <davidlohr@hp.com>, akpm@linux-foundation.org
Cc: aswin@hp.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/5] ipc,msg: always respect MSG_NOERROR
Date: Sun, 18 May 2014 07:53:01 +0200 [thread overview]
Message-ID: <53784ABD.8080209@colorfullife.com> (raw)
In-Reply-To: <1400012857-11733-4-git-send-email-davidlohr@hp.com>
On 05/13/2014 10:27 PM, Davidlohr Bueso wrote:
> When specifying the MSG_NOERROR flag, receivers can avoid returning
> error (E2BIG) and just truncate the message text, if it is too large.
>
> Currently, this logic is only respected when there are already pending
> messages in the queue.
Do you have a test case? The code should handle that
(See below)
> Fix this for the case when there are only
> receivers waiting for a msg to be sent. In order for this to work, save
> the flags in the msg_receiver struct as it must be used later when
> doing the pipeline send.
No, it is sufficient to set the message size to infinity.
> Also do some pipeline_send() cleanups while at it.
No - please don't mix cleanups with bugfixes.
>
> long do_msgsnd(int msqid, long mtype, void __user *mtext,
> @@ -901,6 +907,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl
> list_add_tail(&msr_d.r_list, &msq->q_receivers);
> msr_d.r_tsk = current;
> msr_d.r_msgtype = msgtyp;
> + msr_d.r_msgflg = msgflg;
> msr_d.r_mode = mode;
> if (msgflg & MSG_NOERROR)
> msr_d.r_maxsize = INT_MAX;
^^^^^^
This code should handle MSG_NOERROR:
If MSG_NOERROR is set, then maxsize is set to INT_MAX, therefore -E2BIG
should never be returned.
--
Manfred
next prev parent reply other threads:[~2014-05-18 5:53 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-13 20:27 [PATCH -next 0/5] ipc,msg: fixes and updates Davidlohr Bueso
2014-05-13 20:27 ` [PATCH 1/5] ipc,msg: use current->state helpers Davidlohr Bueso
2014-05-17 17:55 ` Manfred Spraul
2014-05-13 20:27 ` [PATCH 2/5] ipc,msg: move some msgq ns code around Davidlohr Bueso
2014-05-17 17:57 ` Manfred Spraul
2014-05-13 20:27 ` [PATCH 3/5] ipc,msg: always respect MSG_NOERROR Davidlohr Bueso
2014-05-18 5:53 ` Manfred Spraul [this message]
2014-05-18 18:01 ` Davidlohr Bueso
2014-05-19 18:01 ` Manfred Spraul
2014-05-13 20:27 ` [PATCH 4/5] ipc,msg: document volatile r_msg Davidlohr Bueso
2014-05-18 6:08 ` Manfred Spraul
2014-05-13 20:27 ` [PATCH 5/5] ipc,msg: loosen check for full queue Davidlohr Bueso
2014-05-14 18:00 ` Manfred Spraul
2014-05-14 19:50 ` Davidlohr Bueso
2014-05-15 4:20 ` Manfred Spraul
2014-05-15 15:46 ` Davidlohr Bueso
2014-05-16 12:47 ` Michael Kerrisk (man-pages)
2014-05-18 18:16 ` Davidlohr Bueso
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