Re: [PATCH] MIPS: Add smp_call_function_single()

pwatkins
2007-07-30T22:31:05Z

How about this to handle the "call yourself" semantic?

In the other archs, there is more factoring of smp call code, and more care in
the use of get_cpu(). That can be a follow-up MIPS patch.

Signed-off-by: Peter Watkins <pwatkins@sicortex.com>

---
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 67edfa7..33712ff 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -203,6 +203,61 @@ void smp_call_function_interrupt(void)
}
}

+int smp_call_function_single (int cpu, void (*func) (void *info), void *info, int retry,
+ int wait)
+{
+ struct call_data_struct data;
+ int me;
+
+ /*
+ * Can die spectacularly if this CPU isn't yet marked online
+ */
+ if (!cpu_online(cpu))
+ return 0;
+
+ me = get_cpu();
+ BUG_ON(!cpu_online(me));
+
+ if (cpu == me) {
+ local_irq_disable()
+ func(info);
+ local_irq_enable();
+ put_cpu();
+ return 0;
+ }
+
+ /* Can deadlock when called with interrupts disabled */
+ WARN_ON(irqs_disabled());
+
+ data.func = func;
+ data.info = info;
+ atomic_set(&data.started, 0);
+ data.wait = wait;
+ if (wait)
+ atomic_set(&data.finished, 0);
+
+ spin_lock(&smp_call_lock);
+ call_data = &data;
+ smp_mb();
+
+ /* Send a message to the other CPU */
+ core_send_ipi(cpu, SMP_CALL_FUNCTION);
+
+ /* Wait for response */
+ /* FIXME: lock-up detection, backtrace on lock-up */
+ while (atomic_read(&data.started) != 1)
+ barrier();
+
+ if (wait)
+ while (atomic_read(&data.finished) != 1)
+ barrier();
+ call_data = NULL;
+ spin_unlock(&smp_call_lock);
+
+ put_cpu();
+ return 0;
+}
+
static void stop_this_cpu(void *dummy)
{
/*