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SubjectRe: [PATCH -v3] x86: do not free zero sized per cpu areas
On 03/19/2010 03:21 PM, H. Peter Anvin wrote:
> On 03/19/2010 03:18 PM, Yinghai Lu wrote:
>> From: Ian Campbell <ian.campbell@citrix.com>
>>
>> This avoids an infinite loop in free_early_partial().
>>
>> Add a warning to free_early_partial to catch future problems.
>>
>> -v3: according to hpa, don't bother caller.
>>
>> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
>> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@elte.hu>
>> ---
>> kernel/early_res.c | 5 +++++
>> 1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/kernel/early_res.c b/kernel/early_res.c
>> index 3cb2c66..f3a861b 100644
>> --- a/kernel/early_res.c
>> +++ b/kernel/early_res.c
>> @@ -333,6 +333,11 @@ void __init free_early_partial(u64 start, u64 end)
>> struct early_res *r;
>> int i;
>>
>> + if (WARN_ONCE(start >= end,
>> + "free_early_partial got wrong start/end %#llx/%#llx\n",
>> + start, end))
>> + return;
>> +
>> try_next:
>> i = find_overlapped_early(start, end);
>> if (i >= max_early_res)
>
> No, that's wrong.
>
> The workaround is still needed for the case of equality to avoid the
> infinite loop.
>
> So you need an:
>
> if (start == end)
> return;
>

confused, do you mean like this
if (start < end), find_overlapped_early will stop the loop.

From: Ian Campbell <ian.campbell@citrix.com>

This avoids an infinite loop in free_early_partial().

Add a warning to free_early_partial to catch future problems.

-v3: according to hpa, don't bother caller.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
---
kernel/early_res.c | 8 ++++++++
1 file changed, 8 insertions(+)

Index: linux-2.6/kernel/early_res.c
===================================================================
--- linux-2.6.orig/kernel/early_res.c
+++ linux-2.6/kernel/early_res.c
@@ -333,6 +333,14 @@ void __init free_early_partial(u64 start
struct early_res *r;
int i;

+ if (start >= end) {
+ WARN_ONCE(1,
+ "free_early_partial got wrong start/end %#llx/%#llx\n",
+ start, end);
+
+ return;
+ }
+
try_next:
i = find_overlapped_early(start, end);
if (i >= max_early_res)

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