Re: [PATCH] mm/msync: tweak tmpfs patch for syscall msync

[Zumeng Chen <zumeng.chen@windriver.com>]

That was my last version, you can google to get by "msync zumeng"
So feel free to merge it.

Regards,
Zumeng
于 2012年04月25日 21:47, Bruce Ashfield 写道:
> On 12-04-25 06:06 AM, Kang Kai wrote:
>> Commit 1c3ae5441 fixes MIPS CPU cache alias problem. But it makes
>
> Put a short log after the commit ID, that way we can read what the
> old commit was trying to do right in this commit.
>
>> posix test cases mlockall/3-6 3-7 fail.
>
> Can we expand on what the test is doing ? That way the commit
> header is stand alone. I know that I haven't memorized what all the
> posix tests do :)
>
>> Tweak the patch to:
>> 1 check the vma and its flags first
>
> Can you expand here as well. Do you really mean that you've moved
> the CONFIG_TMPFS block down in the function so that the normal
> vma flag checking will occur ?
>
>> 2 don't quit the function when meet first vma belongs to tmpfs file
>
> And for this part, can you (or Zumeng) explain why we used to need
> to exit immediately and now we don't ?
>
> The patch looks good though, thanks for looking into this tricky
> area of code.
>
> Cheers,
>
> Bruce
>
>>
>> Signed-off-by: Kang Kai<kai.kang@windriver.com>
>> ---
>> mm/msync.c | 30 +++++++++++++-----------------
>> 1 files changed, 13 insertions(+), 17 deletions(-)
>>
>> diff --git a/mm/msync.c b/mm/msync.c
>> index ced6215..31cd311 100644
>> --- a/mm/msync.c
>> +++ b/mm/msync.c
>> @@ -60,23 +60,6 @@ SYSCALL_DEFINE3(msync, unsigned long, start, 
>> size_t, len, int, flags)
>> down_read(&mm->mmap_sem);
>> vma = find_vma(mm, start);
>>
>> -#ifdef CONFIG_TMPFS
>> - /*
>> - * For tmpfs, no matter which flag(ASYNC or SYNC) gets from msync,
>> - * there is not so much thing to do for CPUs without cache alias,
>> - * But for some CPUs with cache alias, msync has to flush cache
>> - * explicitly, which makes sure the data coherency between memory
>> - * file and cache.
>> - */
>> - file = vma->vm_file;
>> - if (file&& (file->f_op ==&shmem_file_operations)) {
>> - if(CPU_HAS_CACHE_ALIAS)
>> - flush_cache_range(vma, start, start+len);
>> - error = 0;
>> - goto out_unlock;
>> - }
>> -#endif
>> -
>> for (;;) {
>>
>> /* Still start< end. */
>> @@ -97,6 +80,19 @@ SYSCALL_DEFINE3(msync, unsigned long, start, 
>> size_t, len, int, flags)
>> goto out_unlock;
>> }
>> file = vma->vm_file;
>> +#ifdef CONFIG_TMPFS
>> + /*
>> + * For tmpfs, no matter which flag(ASYNC or SYNC) gets from msync,
>> + * there is not so much thing to do for CPUs without cache alias,
>> + * But for some CPUs with cache alias, msync has to flush cache
>> + * explicitly, which makes sure the data coherency between memory
>> + * file and cache.
>> + */
>> + if (file&& (file->f_op ==&shmem_file_operations)) {
>> + if(CPU_HAS_CACHE_ALIAS)
>> + flush_cache_range(vma, start, start+len);
>> + }
>> +#endif
>> start = vma->vm_end;
>> if ((flags& MS_SYNC)&& file&&
>> (vma->vm_flags& VM_SHARED)) {
>