[patch V2 07/15] powerpc/ps3: Convert half completion to rcuwait

Thomas Gleixner
2020-03-18T20:47:59Z

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>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@lists.ozlabs.org
---
V2: New patch to avoid the magic completion wait variant
---
arch/powerpc/platforms/ps3/device-init.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

--- 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_inte
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(s
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(s
}
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__,