Documentation/x86/topology.txt defines smp_num_siblings as "The number of
threads in a core". Since commit bbb65d2d36 ("x86: use cpuid vector 0xb
when available for detecting cpu topology") smp_num_siblings is the
maximum number of threads in a core. If Simultaneous MultiThreading
(SMT) is disabled on a system, smp_num_siblings is 2 and not 1 as
expected.
Use topology_max_smt_threads(), which contains the active numer of threads,
in the __max_logical_packages calculation.
On a single socket, single core, single thread system __max_smt_threads has
not been updated when the __max_logical_packages calculation happens, so its
zero which makes the package estimate fail. Initialize it to one, which is
the minimum number of threads on a core.
[ tglx: Folded the __max_smt_threads fix in ]
Fixes: b4c0a7326f ("x86/smpboot: Fix __max_logical_packages estimate")
Reported-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Prarit Bhargava <prarit@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jakub Kicinski <kubakici@wp.pl>
Cc: netdev@vger.kernel.org
Cc: "netdev@vger.kernel.org"
Cc: Clark Williams <williams@redhat.com>
Link: https://lkml.kernel.org/r/20171204164521.17870-1-prarit@redhat.com
947134d9b0