Commit 0c39a6a6 authored May 06, 2013 by Colin Cross Committed by Alistair Strachan Dec 05, 2018

ANDROID: fs: epoll: use freezable blocking call

Avoid waking up every thread sleeping in an epoll_wait call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Bug: 77139736
Bug: 120440023
Change-Id: I848d08d28c89302fd42bbbdfa76489a474ab27bf
[ccross: This was upstream (https://lkml.org/lkml/2013/5/6/823), but
         reverted because it reportedly caused memory corruption on
         32-bit x86 (https://patchwork.kernel.org/patch/3162301/).

]
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent d8572161

fs/eventpoll.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -34,6 +34,7 @@
		#include <linux/mutex.h>
		#include <linux/anon_inodes.h>
		#include <linux/device.h>
		#include <linux/freezer.h>
		#include <linux/uaccess.h>
		#include <asm/io.h>
		#include <asm/mman.h>
		@@ -1816,7 +1817,8 @@ static int ep_poll(struct eventpoll ep, struct epoll_event __user events,
		}

		spin_unlock_irq(&ep->wq.lock);
		if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
		if (!freezable_schedule_hrtimeout_range(to, slack,
		HRTIMER_MODE_ABS))
		timed_out = 1;

		spin_lock_irq(&ep->wq.lock);