[PATCH] OLPC: Don't retry EC commands forever

[PATCH] OLPC: Don't retry EC commands forever

[Daniel Drake]

From: Paul Fox <pgf@laptop.org>

Avoids a potential infinite loop

Signed-off-by: Daniel Drake <dsd@laptop.org>
---
 arch/x86/kernel/olpc.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/olpc.c b/arch/x86/kernel/olpc.c
index 37c49934..7472613 100644
--- a/arch/x86/kernel/olpc.c
+++ b/arch/x86/kernel/olpc.c
@@ -114,6 +114,7 @@ int olpc_ec_cmd(unsigned char cmd, unsigned char *inbuf, size_t inlen,
 	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]);
-- 
1.7.2.3

Re: [PATCH] OLPC: Don't retry EC commands forever

[Ingo Molnar]

* Daniel Drake <dsd@laptop.org> wrote:

> From: Paul Fox <pgf@laptop.org>
> 
> Avoids a potential infinite loop

Was this infinite loop observed in practice? I.e. should this get into 
.36 and into -stable?

	Ingo

Re: [PATCH] OLPC: Don't retry EC commands forever

[Daniel Drake]

On 5 October 2010 08:53, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Daniel Drake <dsd@laptop.org> wrote:
>
>> From: Paul Fox <pgf@laptop.org>
>>
>> Avoids a potential infinite loop
>
> Was this infinite loop observed in practice? I.e. should this get into
> .36 and into -stable?

It was observed once, but only during an EC hacking/debugging session
- not in regular operation.
So it should be fine for the next merge window with no need to backport it.

Thanks,
Daniel