Use the GPL-exported bdi_dev_name introduced in kernel 5.7. Do not use
static inline bdi_dev_name in prior kernels because it uses the bdi_unknown_name
symbol which is not exported to GPL modules.
fix: memcg: fix a crash in wb_workfn when a device disappears (5.6)
See upstream commit:
commit 68f23b89067fdf187763e75a56087550624fdbee
("memcg: fix a crash in wb_workfn when a device disappears")
It is currently backported into stable branches 5.4 and 5.5, but appears
to be missing from the 4.4, 4.9, 4.14, 4.19 LTS branches.
Implement our own lttng_bdi_dev_name wrapper to provide this fix on
builds against stable kernels which do not have this fix.
There is one user-visible change with this commit: for builds against
kernels < 4.4.0, the writeback_work_class events did use the
default_backing_dev_info to handle cases where the device is NULL,
writing "default" into the trace. This behavior is now aligned to
match what is done in kernels >= 4.4.0, which is to write "(unknown)"
into the name field.
ea14d58...
by
Michael Jeanson <email address hidden>
fix: RT_PATCH_VERSION is close to overflow
We allocated only 8bits for RT_PATCH_VERSION in LTTNG_RT_VERSION_CODE,
the current RT patch version for the 4.4 branch is currently 214 which
is getting close to 256. Bump it to 16bits to avoid breakage in the
future.
07842fe...
by
Michael Jeanson <email address hidden>
fix: UTS_UBUNTU_RELEASE_ABI is close to overflow
We allocated only 8bits for UTS_UBUNTU_RELEASE_ABI in
LTTNG_UBUNTU_KERNEL_VERSION, the current Xenial kernel has an ABI of 207
which is getting close to 256. Bump it to 16bits to avoid breakage in
the future.
82151df...
by
Michael Jeanson <email address hidden>
fix: sublevel version overflow in LINUX_VERSION_CODE
The 4.4.256 and 4.9.256 stable release overflow the 8bits allocated to
the sublevel in LINUX_VERSION_CODE which ends means they report
themselves as 4.5.0 and 4.10.0 respectively. The next releases in these
stables branches will have sublevel clamped at 255 and will thus report
themselves as 4.4.255 and 4.9.255 for all subsequent releases.
We need a way to way to properly detect these release since I doubt they
will stop breaking tracepoints declarations. As a workaround, extract
the version information from the Makefile in the kernel headers and use
this information to generate a version code when the sublevel is equal
or greater than 256.
