powerpc/ps3: Convert half completion to rcuwait

The PS3 notification interrupt and kthread use a hacked up completion to
communicate. Since we're wanting to change the completion implementation and
this is abuse anyway, replace it with a simple rcuwait since there is only ever
the one waiter.

AFAICT the kthread uses TASK_INTERRUPTIBLE to not increase loadavg, kthreads
cannot receive signals by default and this one doesn't look different. Use
TASK_IDLE instead.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.930037873@linutronix.de

diff --git a/arch/powerpc/platforms/ps3/device-init.c b/arch/powerpc/platforms/ps3/device-init.c
index 2735ec9..e87360a 100644 (file)
--- a/arch/powerpc/platforms/ps3/device-init.c
+++ b/arch/powerpc/platforms/ps3/device-init.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/reboot.h>
+#include <linux/rcuwait.h>
 
 #include <asm/firmware.h>
 #include <asm/lv1call.h>
@@ -670,7 +671,8 @@ struct ps3_notification_device {
        spinlock_t lock;
        u64 tag;
        u64 lv1_status;
-       struct completion done;
+       struct rcuwait wait;
+       bool done;
 };
 
 enum ps3_notify_type {
@@ -712,7 +714,8 @@ static irqreturn_t ps3_notification_interrupt(int irq, void *data)
                pr_debug("%s:%u: completed, status 0x%llx\n", __func__,
                         __LINE__, status);
                dev->lv1_status = status;
-               complete(&dev->done);
+               dev->done = true;
+               rcuwait_wake_up(&dev->wait);
        }
        spin_unlock(&dev->lock);
        return IRQ_HANDLED;
@@ -725,12 +728,12 @@ static int ps3_notification_read_write(struct ps3_notification_device *dev,
        unsigned long flags;
        int res;
 
-       init_completion(&dev->done);
        spin_lock_irqsave(&dev->lock, flags);
        res = write ? lv1_storage_write(dev->sbd.dev_id, 0, 0, 1, 0, lpar,
                                        &dev->tag)
                    : lv1_storage_read(dev->sbd.dev_id, 0, 0, 1, 0, lpar,
                                       &dev->tag);
+       dev->done = false;
        spin_unlock_irqrestore(&dev->lock, flags);
        if (res) {
                pr_err("%s:%u: %s failed %d\n", __func__, __LINE__, op, res);
@@ -738,14 +741,10 @@ static int ps3_notification_read_write(struct ps3_notification_device *dev,
        }
        pr_debug("%s:%u: notification %s issued\n", __func__, __LINE__, op);
 
-       res = wait_event_interruptible(dev->done.wait,
-                                      dev->done.done || kthread_should_stop());
+       rcuwait_wait_event(&dev->wait, dev->done || kthread_should_stop(), TASK_IDLE);
+
        if (kthread_should_stop())
                res = -EINTR;
-       if (res) {
-               pr_debug("%s:%u: interrupted %s\n", __func__, __LINE__, op);
-               return res;
-       }
 
        if (dev->lv1_status) {
                pr_err("%s:%u: %s not completed, status 0x%llx\n", __func__,
@@ -810,6 +809,7 @@ static int ps3_probe_thread(void *data)
        }
 
        spin_lock_init(&dev.lock);
+       rcuwait_init(&dev.wait);
 
        res = request_irq(irq, ps3_notification_interrupt, 0,
                          "ps3_notification", &dev);