Some platforms (will) need to perform allocations before bringing
a new CPU online. Doing it from smp_ops->setup_cpu is the wrong
thing to do:
- It has no useful failure path (too late)
- Calling any allocator will enable interrupts prematurely
causing problems with large decrementer among others
Instead, add a new callback that is called from __cpu_up (so from
the context trying to online the new CPU) at a point where we
can safely allocate and handle failures.
This will be used by XIVE support.
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
---
arch/powerpc/include/asm/smp.h | 1 +
arch/powerpc/kernel/smp.c | 10 ++++++++++
2 files changed, 11 insertions(+)
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 32db16d..2f8e36f 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -44,6 +44,7 @@ struct smp_ops_t {
#endif
void (*probe)(void);
int (*kick_cpu)(int nr);
+ int (*prepare_cpu)(int nr);
void (*setup_cpu)(int nr);
void (*bringup_done)(void);
void (*take_timebase)(void);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 46f89e6..b12f5f0 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -521,6 +521,16 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
cpu_idle_thread_init(cpu, tidle);
+ /*
+ * The platform might need to allocate resources prior to bringing
+ * up the CPU
+ */
+ if (smp_ops->prepare_cpu) {
+ rc = smp_ops->prepare_cpu(cpu);
+ if (rc)
+ return rc;
+ }
+
/* Make sure callin-map entry is 0 (can be leftover a CPU
* hotplug
*/
--
2.9.3
