linux-kernel - Re: [REGRESSION][PATCH] mqueue: Ignore the validity of abs_timeout parameter when message can be performed immediately

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Date:	Wed, 14 Mar 2012 14:46:01 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Akira Takeuchi <takeuchi.akr@...panasonic.com>
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	Carsten Emde <C.Emde@...dl.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Manfred Spraul <manfred@...orfullife.com>
Subject: Re: [REGRESSION][PATCH] mqueue: Ignore the validity of abs_timeout
 parameter when message can be performed immediately

On Fri, 02 Mar 2012 16:42:35 +0900
Akira Takeuchi <takeuchi.akr@...panasonic.com> wrote:

> This patch fixes up the regression problem of mq_timed{send,receive} syscall.
> 
> When a message of mqueue can be performed immediately,
> the validity of abs_timeout parameter should not be checked.
> 
> According to the manpage of mq_timedreceive:
>     Under no circumstance shall the operation fail with a timeout
>     if a message can be removed from the message queue immediately.
>     The validity of the abstime parameter need not be checked
>     if a message can be removed from the message queue immediately.
> 
> On 2.6.35+ kernel, mq_timed{send,receive} returns EINVAL incorrectly,
> in this situation.
> 
> I found this problem during the OPTS testcase
> "conformance/interfaces/mq_timedreceive/10-2":
> 
>     # ./10-2.test
>     FAIL: the validity of abs_timeout is checked
>     Test FAILED

Are you able to identify the commit which caused this regression?  I'm
guessing

commit 9ca7d8e6834c40a99622bbe4a88aaf64313ae43c
Author:     Carsten Emde <C.Emde@...dl.org>
AuthorDate: Fri Apr 2 22:40:20 2010 +0200
Commit:     Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue Apr 6 21:50:03 2010 +0200

    mqueue: Convert message queue timeout to use hrtimers                       


> Signed-off-by: Akira Takeuchi <takeuchi.akr@...panasonic.com>
> Signed-off-by: Kiyoshi Owada <owada.kiyoshi@...panasonic.com>
> ---
>  ipc/mqueue.c |   31 +++++++++++++++++++++++++++----
>  1 files changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/ipc/mqueue.c b/ipc/mqueue.c
> index 86ee272..7cd4411 100644
> --- a/ipc/mqueue.c
> +++ b/ipc/mqueue.c
> @@ -861,14 +861,22 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
>  	struct msg_msg *msg_ptr;
>  	struct mqueue_inode_info *info;
>  	ktime_t expires, *timeout = NULL;
> +	int timeout_param_error = 0;
>  	struct timespec ts;
>  	int ret;
>  
>  	if (u_abs_timeout) {
>  		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
>  		if (res)
> -			return res;
> -		timeout = &expires;
> +			/*
> +			 * The validity of the abs_timeout parameter need not be
> +			 * checked when there is sufficient room in the queue.
> +			 * So, do not return here, even if the parameter is
> +			 * invalid.
> +			 */
> +			timeout_param_error = res;
> +		else
> +			timeout = &expires;
>  	}
>  
>  	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
> @@ -916,6 +924,9 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
>  		if (filp->f_flags & O_NONBLOCK) {
>  			spin_unlock(&info->lock);
>  			ret = -EAGAIN;
> +		} else if (unlikely(timeout_param_error)) {
> +			spin_unlock(&info->lock);
> +			ret = timeout_param_error;
>  		} else {
>  			wait.task = current;
>  			wait.msg = (void *) msg_ptr;
> @@ -955,13 +966,21 @@ SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
>  	struct mqueue_inode_info *info;
>  	struct ext_wait_queue wait;
>  	ktime_t expires, *timeout = NULL;
> +	int timeout_param_error = 0;
>  	struct timespec ts;
>  
>  	if (u_abs_timeout) {
>  		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
>  		if (res)
> -			return res;
> -		timeout = &expires;
> +			/*
> +			 * The validity of the abs_timeout parameter need not be
> +			 * checked if a message can be removed from the message
> +			 * queue immediately. So, do not return here, even if
> +			 * the parameter is invalid.
> +			 */
> +			timeout_param_error = res;
> +		else
> +			timeout = &expires;
>  	}
>  
>  	audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
> @@ -996,6 +1015,10 @@ SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
>  		if (filp->f_flags & O_NONBLOCK) {
>  			spin_unlock(&info->lock);
>  			ret = -EAGAIN;
> +		} else if (unlikely(timeout_param_error)) {
> +			spin_unlock(&info->lock);
> +			ret = timeout_param_error;
> +			msg_ptr = NULL; /* just for shutting up warning */
>  		} else {
>  			wait.task = current;
>  			wait.state = STATE_NONE;
> -- 
> 1.7.4.1
> 
> 
> --
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