[PATCH V2] arm64: psci: Reduce waiting time of cpu_psci_cpu_kill()

[Yunfeng Ye]

If psci_ops.affinity_info() fails, it will sleep 10ms, which will not
take so long in the right case. Use usleep_range() instead of msleep(),
reduce the waiting time, and give a chance to busy wait before sleep.

Signed-off-by: Yunfeng Ye <yeyunf...@huawei.com>
---
V1->V2:
- use usleep_range() instead of udelay() after waiting for a while

 arch/arm64/kernel/psci.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index c9f72b2..99b3122 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -82,6 +82,7 @@ static void cpu_psci_cpu_die(unsigned int cpu)
 static int cpu_psci_cpu_kill(unsigned int cpu)
 {
        int err, i;
+       unsigned long timeout;

        if (!psci_ops.affinity_info)
                return 0;
@@ -91,16 +92,24 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
         * while it is dying. So, try again a few times.
         */

-       for (i = 0; i < 10; i++) {
+       i = 0;
+       timeout = jiffies + msecs_to_jiffies(100);
+       do {
                err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
                if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
                        pr_info("CPU%d killed.\n", cpu);
                        return 0;
                }

-               msleep(10);
-               pr_info("Retrying again to check for CPU kill\n");
-       }
+               /* busy-wait max 1ms */
+               if (i++ < 100) {
+                       cond_resched();
+                       udelay(10);
+                       continue;
+               }
+
+               usleep_range(100, 1000);
+       } while (time_before(jiffies, timeout));

        pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports 
%d)\n",
                        cpu, err);
-- 
2.7.4.3