Re: [Qemu-devel] [PATCH] exec-obsolete: fix length handling

[Blue Swirl]

On Sun, Jan 29, 2012 at 12:08, Avi Kivity <address@hidden> wrote:
> On 01/28/2012 08:13 PM, Blue Swirl wrote:
>> Fix suspend/resume broken by off-by-one error in
>> 59abb06198ee9471e29c970f294eae80c0b39be1.
>>
>> Adjust the loop so that it handles correctly the case
>> start = (ram_addr_t)-TARGET_PAGE_SIZE, length = TARGET_PAGE_SIZE.
>>
>> Reported-by: Stefan Berger <address@hidden>
>> Signed-off-by: Blue Swirl <address@hidden>
>> ---
>>  exec-obsolete.h |   10 ++++------
>>  1 files changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/exec-obsolete.h b/exec-obsolete.h
>> index 03cf35e..1bba970 100644
>> --- a/exec-obsolete.h
>> +++ b/exec-obsolete.h
>> @@ -81,11 +81,10 @@ static inline void
>> cpu_physical_memory_set_dirty_range(ram_addr_t start,
>>                                                         int dirty_flags)
>>  {
>>      uint8_t *p;
>> -    ram_addr_t addr, end;
>> +    ram_addr_t cur;
>>
>> -    end = start + length;
>>      p = ram_list.phys_dirty + (start >> TARGET_PAGE_BITS);
>> -    for (addr = start; addr <= end; addr += TARGET_PAGE_SIZE) {
>> +    for (cur = 0; cur < length; cur += TARGET_PAGE_SIZE) {
>>          *p++ |= dirty_flags;
>>      }
>
> I think this is still wrong - if length == 2 it will iterate once, but
> we need two iterations if start == 0xfff.

Yes, tricky. We could do something like
for (cur = start & TARGET_PAGE_MASK; cur < length; cur += TARGET_PAGE_SIZE) {
but I'll send a new patch with just s/<=/</.

>
>
> --
> error compiling committee.c: too many arguments to function
>