powerpc/smp: add NULL guard for cause_ipi in smp_muxed_ipi_message_pass

smp_muxed_ipi_message_pass() calls smp_ops->cause_ipi() without
checking whether it has been set.

On platforms using muxed IPI (e.g. powernv/pseries), smp_ops->cause_ipi
is initialized to NULL in the static smp_ops and only assigned during
the platform smp_probe() handler.  If the IPI subsystem fails to
initialize -- for example when xive_init_ipis() fails and
xive_smp_probe() returns an error -- the probe handler returns early
and cause_ipi is never set.  Any subsequent IPI send (e.g.
arch_smp_send_reschedule()) would dereference the NULL pointer.

Add a NULL check to avoid the crash in that situation.

Fixes: 23d72bfd8f9f ("powerpc: Consolidate ipi message mux and demux")
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-6-gouhao@uniontech.com

0 files changed, 0 insertions, 0 deletions