ptem01 LTP failure in ttydev-0909

[sukadev at linux.vnet.ibm.com]

Sorry, this was buried in my inbox...

Subrata Modak [subrata at linux.vnet.ibm.com] wrote:
| Hi Sukadev,
| 
| On Thu, 2008-09-18 at 21:14 -0700, sukadev at linux.vnet.ibm.com wrote:
| > Alan Cox [alan at lxorguk.ukuu.org.uk] wrote:
| > | > The test changes the window size using the slave-fd and expects that
| > | > it won't affect the window-size on master-fd. With this change, we
| > | > return the slave's window size and test fails.
| > | 
| > | I've no idea why anyone would have thought the existing behaviour was
| > | correct. The pty/tty pair code tries to share the size and other
| > | information at all times and the old test was I think verifying a bug
| > | existed.
| > | 
| > | Unless anyone can cite anything to show otherwise anyway ?
| > 
| > Subrata 
| > 
| > We are referring to the last window size check in test2() of
| > testcases/kernel/pty/ptem01.c. This check will cause the test
| > to fail when some of the planned ttydev changes are merged.
| > 
| > Would you happen to know if the check is really required or if
| > it should be dropped ?
| 
|  I would want the test to remain there, but introduce some checkings
| before running the test. As test2() is valid under present
| circumstances, we should retain it as people will keep using LTP on
| lower kernels.

Just to be clear, the entire test2() is not broken. Only the last part
(see patch below) Other parts of test2() should be fine even with
new changes.

| 
| Having said that, i would like to come with a solution where test2() of
| testcases/kernel/pty/ptem01.c is not run after the planned ttydev
| changes are merged. Something compile/run time checking to either not to
| build that part of code and run it. Can we do something like that by
| checking some glibc/kernel exported definitions ?

Other than the kernel version when the changes are merged, I am not sure
there is a way. Besides, it is not clear which assertion that part of
test2() is testing and if it is even needed for older kernels.

Here is the part of test2() I am referring to:

---
 testcases/kernel/pty/ptem01.c |   12 ------------
 1 file changed, 12 deletions(-)

Index: ltp-full-20071031/testcases/kernel/pty/ptem01.c
===================================================================
--- ltp-full-20071031.orig/testcases/kernel/pty/ptem01.c        2008-11-01 13:30:42.977954127 -0700
+++ ltp-full-20071031/testcases/kernel/pty/ptem01.c     2008-11-01 13:31:41.439427078 -0700
@@ -238,18 +238,6 @@ test2(void)
                tst_exit();
        }

-       if (ioctl(masterfd, TIOCGWINSZ, &wsz) != 0) {
-               tst_resm(TFAIL,"TIOCGWINSZ");
-               tst_exit();
-       }
-
-       if (wsz.ws_row == wsz2.ws_row || wsz.ws_col == wsz2.ws_col ||
-           wsz.ws_xpixel == wsz2.ws_xpixel ||
-           wsz.ws_ypixel == wsz2.ws_ypixel) {
-               tst_resm(TFAIL, "unexpected window size returned");
-               tst_exit();
-       }
-
        if (close(slavefd) != 0) {
                tst_resm(TBROK,"close");
                tst_exit();