linux-kernel - [RFC][PATCH v2] epoll: allow EPOLLWAKEUP flag if PM

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Date:	Wed, 13 Nov 2013 02:22:28 +0530
From:	Amit Pundir <amit.pundir@...aro.org>
To:	Arve Hjønnevåg <arve@...roid.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	John Stultz <john.stultz@...aro.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Android Kernel Team <kernel-team@...roid.com>
Subject: [RFC][PATCH v2] epoll: allow EPOLLWAKEUP flag if PM_SLEEP is enabled

ep_create_wakeup_source() reports ENOMEM if wakeup_source_register()
returns NULL. ep_create_wakeup_source() assumes that NULL is only
returned if we run into ENOMEM but NULL is also returned when
CONFIG_PM_SLEEP is disabled.

Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
---
Changed in v2:
Using static inline functions instead of #ifdefs
---
 fs/eventpoll.c                 |    3 +--
 include/uapi/linux/eventpoll.h |   12 ++++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 473e09d..10f9c43 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1820,8 +1820,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
 		goto error_tgt_fput;
 
 	/* Check if EPOLLWAKEUP is allowed */
-	if ((epds.events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND))
-		epds.events &= ~EPOLLWAKEUP;
+	ep_epollwakeup_check(&epds.events);
 
 	/*
 	 * We have to check that the file structure underneath the file descriptor
diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h
index 2c267bc..1d139c2 100644
--- a/include/uapi/linux/eventpoll.h
+++ b/include/uapi/linux/eventpoll.h
@@ -62,4 +62,16 @@ struct epoll_event {
 } EPOLL_PACKED;
 
 
+#ifdef CONFIG_PM_SLEEP
+static inline void ep_epollwakeup_check(__u32 *epev)
+{
+	if ((*epev & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND))
+		*epev &= ~EPOLLWAKEUP;
+}
+#else
+static inline void ep_epollwakeup_check(__u32 *epev)
+{
+	*epev &= ~EPOLLWAKEUP;
+}
+#endif
 #endif /* _UAPI_LINUX_EVENTPOLL_H */
-- 
1.7.10.4

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