linux-kernel - [PATCH v3 3/4] cpuidle-haltpoll: return -ENODEV on modinit failure

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Message-Id: <20190907234524.5577-4-joao.m.martins@oracle.com>
Date:   Sun,  8 Sep 2019 00:45:23 +0100
From:   Joao Martins <joao.m.martins@...cle.com>
To:     linux-pm@...r.kernel.org
Cc:     Joao Martins <joao.m.martins@...cle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-kernel@...r.kernel.org,
        Marcelo Tosatti <mtosatti@...hat.com>, kvm@...r.kernel.org
Subject: [PATCH v3 3/4] cpuidle-haltpoll: return -ENODEV on modinit failure

When a user loads cpuidle-haltpoll on a non KVM guest the module will
successfully load, even though idle driver registration didn't take
place.

We should instead return -ENODEV signaling the user that the driver can't
be loaded, like other error paths in haltpoll_init().  An example of such
error paths is when we return -EBUSY when attempting to register an idle
driver when it had one already (e.g. intel_idle loads at boot and then we
attempt to insert module cpuidle-haltpoll).

Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver")
Signed-off-by: Joao Martins <joao.m.martins@...cle.com>
---
v2:
 * Added Fixes tag
---
 drivers/cpuidle/cpuidle-haltpoll.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
index 519e90d125cf..7a0239ef717e 100644
--- a/drivers/cpuidle/cpuidle-haltpoll.c
+++ b/drivers/cpuidle/cpuidle-haltpoll.c
@@ -99,7 +99,7 @@ static int __init haltpoll_init(void)
 	cpuidle_poll_state_init(drv);
 
 	if (!kvm_para_available())
-		return 0;
+		return -ENODEV;
 
 	ret = cpuidle_register_driver(drv);
 	if (ret < 0)
-- 
2.17.1