[LTP] [PATCH v2 3/5] swapon03: Try to swapon() as many files until it fails

[Petr Vorel]

Hi Cyril,

> Hi!
> >  	is_swap_supported(TEST_FILE);
> > +
> > +	swapfiles = SAFE_MMAP(NULL, sizeof(*swapfiles), PROT_READ | PROT_WRITE,
> > +			MAP_SHARED | MAP_ANONYMOUS, -1, 0);
> > +	*swapfiles = 0;
> > +
> >  	setup_swap();
> >  }

> >  static void cleanup(void)
> >  {
> > -	clean_swap();
> > +	if (swapfiles) {
> > +		clean_swap();
> > +		SAFE_MUNMAP(swapfiles, sizeof(*swapfiles));
> > +	}
> >  }

First, thank you for your review!

> This gets complicated for no good reason since we run the setup code in the
> child.

If swapfiles is not mapped for some reason (can happen or "*swapfiles = 0" is
not run (that should not happen), then using *swapfiles leads to segfault.

*swapfiles is being used not only in SAFE_MUNMAP() here in cleanup(), but
also in clean_swap().

Also, this saves trying to deactivate swap files if they weren't activated.

And, unless "swapon03: Remove grep dependency" (the last commit) is accepted,
there is a corner case I found during debugging:

# ./swapon03 # quit early with ctrl+C => some swap partitions are left not being swapped off
...
Sending SIGKILL to test process...
tst_test.c:1909: TINFO: Killed the leftover descendant processes
tst_test.c:1918: TINFO: If you are running on slow machine, try exporting LTP_TIMEOUT_MUL > 1
tst_test.c:1920: TBROK: Test killed! (timeout?)

Summary:
passed   0
failed   0
broken   1
skipped  0
warnings 0
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  1...
tst_device.c:421: TINFO: Likely gvfsd-trash is probing newly mounted fs, kill it to speed up tests.
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  2...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  3...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  4...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  5...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  6...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  7...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  8...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try  9...
tst_device.c:417: TINFO: umount('mntpoint') failed with EBUSY, try 10...

Then following run tries to swapoff() partition left from previous run.

# ./swapon03
...
swapon03.c:80: TWARN: Failed to swapoff mntpoint/testswap

But the last commit fixes this problem.

Kind regards,
Petr