linux-kernel - [20/66] x86, olpc: Dont retry EC commands forever

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Date:	Fri, 19 Nov 2010 14:00:51 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Daniel Drake <dsd@...top.org>, dilinger@...ued.net,
	Ingo Molnar <mingo@...e.hu>
Subject: [20/66] x86, olpc: Dont retry EC commands forever

2.6.36-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Paul Fox <pgf@...top.org>

commit 286e5b97eb22baab9d9a41ca76c6b933a484252c upstream.

Avoids a potential infinite loop.

It was observed once, during an EC hacking/debugging
session - not in regular operation.

Signed-off-by: Daniel Drake <dsd@...top.org>
Cc: dilinger@...ued.net
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/kernel/olpc.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/olpc.c
+++ b/arch/x86/kernel/olpc.c
@@ -114,6 +114,7 @@ int olpc_ec_cmd(unsigned char cmd, unsig
 	unsigned long flags;
 	int ret = -EIO;
 	int i;
+	int restarts = 0;
 
 	spin_lock_irqsave(&ec_lock, flags);
 
@@ -169,7 +170,9 @@ restart:
 			if (wait_on_obf(0x6c, 1)) {
 				printk(KERN_ERR "olpc-ec:  timeout waiting for"
 						" EC to provide data!\n");
-				goto restart;
+				if (restarts++ < 10)
+					goto restart;
+				goto err;
 			}
 			outbuf[i] = inb(0x68);
 			pr_devel("olpc-ec:  received 0x%x\n", outbuf[i]);


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