linux-kernel - [RFC][PATCH] rtsx_usb_ms: Use msleep

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Message-ID: <489b0107c6a086e82f8eb17c0f64e0d0@natalenko.name>
Date:	Tue, 15 Mar 2016 20:30:19 +0200
From:	Oleksandr Natalenko <oleksandr@...alenko.name>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	Ben Hutchings <ben@...adent.org.uk>,
	Wolfram Sang <wsa@...-dreams.de>,
	Roger Tseng <rogerable@...ltek.com>,
	linux-kernel@...r.kernel.org
Subject: [RFC][PATCH] rtsx_usb_ms: Use msleep_interruptible() in polling loop

This patch has already been posted to LKML by Ben Hutchings ~5 months 
ago, but AFAIK no further action were performed. However, this patch 
really fixes weird loadavg with RTS5129 card reader, so I would wonder 
if this could be merged. AFAIK, it has been applied to some distros' 
kernels, e.g., Ubuntu.

Original Ben's message goes below.

rtsx_usb_ms creates a task that mostly sleeps, but tasks in
uninterruptible sleep still contribute to the load average (for
bug-compatibility with Unix).  A load average of ~1 on a system that
should be idle is somewhat alarming.

Change the sleep to be interruptible, but still ignore signals.

A better fix might be to replace this loop with a delayed work item.

References: https://bugs.debian.org/765717
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Oleksandr Natalenko <oleksandr@...alenko.name>
---
  drivers/memstick/host/rtsx_usb_ms.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/memstick/host/rtsx_usb_ms.c 
b/drivers/memstick/host/rtsx_usb_ms.c
index 1105db2..645dede 100644
--- a/drivers/memstick/host/rtsx_usb_ms.c
+++ b/drivers/memstick/host/rtsx_usb_ms.c
@@ -706,7 +706,8 @@ poll_again:
  		if (host->eject)
  			break;

-		msleep(1000);
+		if (msleep_interruptible(1000))
+			flush_signals(current);
  	}

  	complete(&host->detect_ms_exit);
-- 
2.7.3