Re: [LTP] [PATCH] Simple tests for cross memory attach (process_vm_[readv|writev] syscalls)

[Jan Stancek <jstancek@redhat.com>]

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On 05/15/2012 04:56 PM, Jan Stancek wrote:
> 
> 
> ----- Original Message -----
>> From: "Caspar Zhang" <caspar@casparzhang.com>
>> To: "Christopher Yeoh" <cyeoh@au1.ibm.com>
>> Cc: ltp-list@lists.sourceforge.net, "Jan Stancek" <jstancek@redhat.com>
>> Sent: Wednesday, 9 May, 2012 3:00:51 PM
>> Subject: Re: [LTP] [PATCH] Simple tests for cross memory attach (process_vm_[readv|writev] syscalls)
>> Hi Chris, thanks very much for the patch, I tried to backport your
>> testcases in http://ozlabs.org/~cyeoh/cma/ to LTP and composed an
>> unfinished version, then I was busy for other things. I'm happy to
>> see
>> you can backport it by yourself :) There are some more new cma
>> patches
>> (aims on testing retcode and errnos) sent by Jan Stancek (cc-ed) [1],
>> I
>> think we need to discuss the testcase organization..
>>
>> And I will review the testcases when I get more free time.
> 
> Hi,
> 
> I looked at testcases sent by Chris. Good news is, they
> do not overlap (in terms of functionality) with mine :-).
> 
> The patch need some polishing to match the style guide:
> - indentation
> - I think output should be TINFO, rather than plain printf
> - single statement if without { }
> - I would split some code to more functions, for example process_vm_writev01.c
>   main function seems complex
> 
> As for test organization, I think we need to decide 2 issues:
> 1. directory structure
> a)
>   testcases/kernel/syscalls/cma/
>   testcases/kernel/syscalls/cma/process_vm_readv
>   testcases/kernel/syscalls/cma/process_vm_writev
> b)
>   testcases/kernel/syscalls/process_vm_readv
>   testcases/kernel/syscalls/process_vm_writev
> 
> I'm preferring a) as these 2 syscalls are closely related,
> and we already have need to share code.
> 
> 2. how to invoke new syscalls
> a)
> Patch from Chris is defining new syscall numbers in test and
> using syscall(2).
> 
> b)
> My patch adds configure check for glibc wrappers process_vm_readv/writev
> and if those does not exists it checks for __NR_process_vm_readv.
> 
> I think we should not define syscall numbers in tests directly,
> but I'm relying on LTP maintainers to provide guidance here.
> In any case, if you run it on older kernel it should end with TCONF.
> 
> I would go with using Chris' process_vm.h, but remove syscall number
> defines and use names that wont conflict with glibc wrappers:
> test_process_vm_readv
> test_process_vm_writev
> 
> These could be function pointers, that would get initialized with
> function using glibc wrapper
> function using syscall(__NR_process_vm_readv,..)
> or NULL
> 
> each testcase could check in setup for NULL, and end with TCONF,
> if there is no way invoke that syscall.
> 
> There was question from Caspar, if we should check for both glibc wrapper
> and syscall number (http://thread.gmane.org/gmane.linux.ltp/16055).
> I think we should, as we use glibc wrappers by default.
> 
> Any thoughts?

I'm attaching sample process_vm.h for illustration.
This would go on top of:
http://thread.gmane.org/gmane.linux.ltp/16053
http://thread.gmane.org/gmane.linux.ltp/16054

each test would include that, check ltp_process_vm_readv/writev for NULL
and optionally end with TCONF or continue.

Regards,
Jan

> 
> Regards,
> Jan
> 
>>
>> Thanks,
>> Caspar
>>
>> [1]
>> http://thread.gmane.org/gmane.linux.ltp/16052
>> http://thread.gmane.org/gmane.linux.ltp/16053
>> http://thread.gmane.org/gmane.linux.ltp/16054
>> http://thread.gmane.org/gmane.linux.ltp/16055
>>


[-- Attachment #2: process_vm.h --]
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/*
 * Copyright (C) 2012 Linux Test Project, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it
 * is free of the rightful claim of any third person regarding
 * infringement or the like.  Any license provided herein, whether
 * implied or otherwise, applies only to this software file.  Patent
 * licenses, if any, provided herein do not apply to combinations of
 * this program with other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#ifndef _PROCESS_VM_H_
#define _PROCESS_VM_H_

#include <sys/syscall.h>
#include <sys/uio.h>
#include <unistd.h>

#define CMA_PARAMS pid, lvec, liovcnt, rvec, riovcnt, flags
#define CMA_PARAMS_TYPES pid_t pid, const struct iovec *lvec, unsigned long liovcnt,\
        const struct iovec *rvec, unsigned long riovcnt, unsigned long flags
#define CMA_FUNC_PROTO(func_name) ssize_t func_name(CMA_PARAMS_TYPES)
#define CMA_FUNCP_PROTO(func_name) ssize_t (*func_name)(CMA_PARAMS_TYPES)

/* 
 * process_vm_readv 
 */
#if (HAVE_PROCESS_VM_READV==1)
static inline CMA_FUNC_PROTO(ltp_process_vm_readv)
{
    return process_vm_readv(CMA_PARAMS);
}
#elif defined(__NR_process_vm_readv)
static inline CMA_FUNC_PROTO(ltp_process_vm_readv)
{
    return syscall(__NR_process_vm_readv, CMA_PARAMS);
}
#else
CMA_FUNCP_PROTO(ltp_process_vm_readv) = NULL;
#endif

/* 
 * process_vm_writev 
 */
#if (HAVE_PROCESS_VM_WRITEV==1)
static inline CMA_FUNC_PROTO(ltp_process_vm_writev)
{
    return process_vm_writev(CMA_PARAMS);
}
#elif defined(__NR_process_vm_writev)
static inline CMA_FUNC_PROTO(ltp_process_vm_writev)
{
    return syscall(__NR_process_vm_writev, CMA_PARAMS);
}
#else
CMA_FUNCP_PROTO(ltp_process_vm_writev) = NULL;
#endif

#endif /* _PROCESS_VM_H_ */

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