On 27/3/21 1:19 am, Daniel Henrique Barboza wrote:
One of the reasons that dlpar_cpu_offline can fail is when attempting to
offline the last online CPU of the kernel. This can be observed in a
pseries QEMU guest that has hotplugged CPUs. If the user offlines all
other CPUs of the guest, and a hotplugged CPU is now the last online
CPU, trying to reclaim it will fail. See [1] for an example.
The current error message in this situation returns rc with -EBUSY and a
generic explanation, e.g.:
pseries-hotplug-cpu: Failed to offline CPU PowerPC,POWER9, rc: -16
EBUSY can be caused by other conditions, such as cpu_hotplug_disable
being true. Throwing a more specific error message for this case,
instead of just "Failed to offline CPU", makes it clearer that the error
is in fact a known error situation instead of other generic/unknown
cause.
This patch adds a 'last online' check in dlpar_cpu_offline() to catch
the 'last online CPU' offline error, returning a more informative error
message:
pseries-hotplug-cpu: Unable to remove last online CPU PowerPC,POWER9
[1] https://bugzilla.redhat.com/1911414
Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com>
Thanks for addressing the issues in Daniel's review.
I haven't tested it, but this patch looks sensible enough to me.
Reviewed-by: Andrew Donnellan <a...@linux.ibm.com>
--
Andrew Donnellan OzLabs, ADL Canberra
a...@linux.ibm.com IBM Australia Limited
