linux-kernel - [PATCH] powerpc: eeh_event: convert semaphore to completion

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Date:   Mon, 10 Dec 2018 22:51:57 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Russell Currey <ruscur@...sell.cc>,
        Sam Bobroff <sbobroff@...ux.ibm.com>,
        "Oliver O'Halloran" <oohall@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH] powerpc: eeh_event: convert semaphore to completion

For this use case, completions and semaphores are equivalent,
but semaphores are an awkward interface that should generally
be avoided, so use the completion instead.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/powerpc/kernel/eeh_event.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/eeh_event.c b/arch/powerpc/kernel/eeh_event.c
index 61c9356bf9c9..227e57f980df 100644
--- a/arch/powerpc/kernel/eeh_event.c
+++ b/arch/powerpc/kernel/eeh_event.c
@@ -35,7 +35,7 @@
  */
 
 static DEFINE_SPINLOCK(eeh_eventlist_lock);
-static struct semaphore eeh_eventlist_sem;
+static DECLARE_COMPLETION(eeh_eventlist_event);
 static LIST_HEAD(eeh_eventlist);
 
 /**
@@ -55,7 +55,7 @@ static int eeh_event_handler(void * dummy)
 	struct eeh_pe *pe;
 
 	while (!kthread_should_stop()) {
-		if (down_interruptible(&eeh_eventlist_sem))
+		if (wait_for_completion_interruptible(&eeh_eventlist_event))
 			break;
 
 		/* Fetch EEH event from the queue */
@@ -102,9 +102,6 @@ int eeh_event_init(void)
 	struct task_struct *t;
 	int ret = 0;
 
-	/* Initialize semaphore */
-	sema_init(&eeh_eventlist_sem, 0);
-
 	t = kthread_run(eeh_event_handler, NULL, "eehd");
 	if (IS_ERR(t)) {
 		ret = PTR_ERR(t);
@@ -142,7 +139,7 @@ int eeh_send_failure_event(struct eeh_pe *pe)
 	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
 
 	/* For EEH deamon to knick in */
-	up(&eeh_eventlist_sem);
+	complete(&eeh_eventlist_event);
 
 	return 0;
 }
-- 
2.20.0