Re: [LTP] [PATCH 1/4] syscall/process_vm_readv02: new testcase

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Jan Stancek" <jstancek@redhat.com>
> To: "Caspar Zhang" <caspar@casparzhang.com>
> Cc: "LTP List" <ltp-list@lists.sourceforge.net>
> Sent: Wednesday, 8 August, 2012 12:52:42 PM
> Subject: Re: [LTP] [PATCH 1/4] syscall/process_vm_readv02: new testcase
> 
> Hi Caspar,
> 
> +	if (TEST_RETURN != len)
> +		tst_brkm(TBROK|TERRNO, tst_exit, "process_vm_readv");
> Shouldn't this be TFAIL? Can it also print TEST_RETURN?
> 
> +	lp = SAFE_MALLOC(tst_exit, len + 1);
> +	local.iov_base  = lp;
> +	local.iov_len   = len;
> +	remote.iov_base = rp;
> +	remote.iov_len  = len;
> +
> +	tst_resm(TINFO, "child 1: reading string from same memory
> location.");
> +	TEST(test_process_vm_readv(pids[0], &local, 1, &remote, 1, 0));
> +	if (TEST_RETURN != len)
> +		tst_brkm(TBROK|TERRNO, tst_exit, "process_vm_readv");
> +	if (strcmp(lp, tst_string) != 0)
> +		tst_brkm(TFAIL, tst_exit, "child 1: expected string: %s, "
> +			    "received string: %s", tst_string, lp);
> I think SAFE_MALLOC is not initialising memory. So if "lp[len] != 0"
> strcmp will fail.
> 
> +#if !defined(__NR_process_vm_readv)
> +	tst_brkm(TCONF, NULL, "process_vm_writev does not exist "
> +		    "on your system");
> Message says "process_vm_writev", testcase is for "process_vm_readv".

+			tst_brkm(TBROK|TERRNO, cleanup, "fork #0");
Both messages about broken fork are "fork #0".

SIGSTOP/SIGCONT approach seems prone to races: if other child
is able to finish before first one raises SIGSTOP, then SIGCONT
arrives first. For example, let's put small sleep before SIGSTOP
in child_alloc() and child will never finish:

    sleep(2);
    if (raise(SIGSTOP) < 0)
            tst_brkm(TBROK|TERRNO, tst_exit, "raise");

The testcase still gives PASS, but one of children is now hanging
in background:
 5399 pts/0    T      0:00 ./process_vm_readv02

Regards,
Jan

> 
> Regards,
> Jan
> 
> ----- Original Message -----
> > From: "Caspar Zhang" <caspar@casparzhang.com>
> > To: "LTP List" <ltp-list@lists.sourceforge.net>
> > Sent: Wednesday, 8 August, 2012 11:26:54 AM
> > Subject: [LTP] [PATCH 1/4] syscall/process_vm_readv02: new testcase
> > 
> > 
> > This testcase is one of the simple CMA syscalls (process_vm_readv,
> > process_vm_writev) tests originally written by Chris Yeoh
> > <yeohc@au1.ibm.com>. I made some modifications to make it match the
> > code
> > style in LTP.
> > 
> > Test Assertion and Strategy:
> > 
> >     Fork two children, one child allocates memory and initializes
> >     it;
> >     then the other one calls process_vm_readv and reads from the
> >     same
> >     memory location, it then verifies if process_vm_readv returns
> >     correct data.
> > 
> > Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
> > ---
> >  testcases/kernel/syscalls/cma/process_vm_readv02.c |  162
> >  ++++++++++++++++++++
> >  1 files changed, 162 insertions(+), 0 deletions(-)
> >  create mode 100644
> >  testcases/kernel/syscalls/cma/process_vm_readv02.c
> > 
> > 
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