[OpenAFS-devel] Re: [OpenAFS] getcwd() error for RHEL 7.4 kernel

[Stephan Wiesand]

[taking this thread to -devel]

> On 20. Oct 2017, at 12:04, Stephan Wiesand <stephan.wiesand@desy.de> =
wrote:
>=20
> I ran configure against the EL7.3 and EL7.4 GA kernels (3.10.0-514.el7 =
and 3.10.0-696.el7) and compared the results.
>=20
> Besides the fact that in the 7.4 case conftest.c is compiled with an =
additional -DCONFIG_AVX512, which I doubt makes a difference, there are =
some differences in configure test results:
>=20
> 			7.3	7.4
> locks_lock_file_wait	no	yes
> inode_lock		no	yes
> exported tasklist_lock	yes	no

It turns out the EL7.4 kernel turns tasklist_lock from an rwlock_t into =
a qrwlock_t and all read_{,un}lock() calls into qread_{,un}lock() ones. =
And no, it's not what mainline kernels do, including 4.14-rc5.

We should probably adapt to this, and I guess it shouldn't be too hard, =
but is this change likely to be the reason for more frequent getcwd() =
problems?

--=20
Stephan Wiesand
DESY -DV-
Platanenallee 6
15738 Zeuthen, Germany