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SubjectRe: [RFC][PATCH] f2fs: Avoid print false deadlock messages.
On 05/15/2013 03:21 PM, Libo Chen wrote:
> On 2013/5/15 14:58, majianpeng wrote:
>> By adding some messages, i found this problem because the gcc
>> optimizing. For those codes:
>>>> for (i = 0; i < NR_GLOBAL_LOCKS; i++)
>>>> mutex_init(&sbi->fs_lock[i]);
>> The defination of mutex_init is:
>>>> #define mutex_init(mutex)
>>>> do {
>>>>
>>>> static struct lock_class_key __key;
>>>>
>>>>
>>>> __mutex_init((mutex), #mutex, &__key);
>>>>
>>>> } while (0)
>> Because the optimizing of gcc, there are only one __key rather than
>> NR_GLOBAL_LOCKS times.
>>
>> Add there is other problems about lockname.Using 'for()' the lockname is
>> the same which is '&sbi->fs_lock[i]'.If it met problem about
>> mutex-operation, it can't find which one.
>>
>> Although my patch can work,i think it's not best.Because if
>> NR_GLOBAL_LOCKS changed, we may leak to change this.
>>
>> BTY, if who know how to avoid optimize, please tell me. Thanks!
>>
>> Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
>> ---
>> fs/f2fs/super.c | 13 ++++++++++---
>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 8555f7d..ce08b96 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -520,7 +520,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>> struct buffer_head *raw_super_buf;
>> struct inode *root;
>> long err = -EINVAL;
>> - int i;
>>
>> /* allocate memory for f2fs-specific super block info */
>> sbi = kzalloc(sizeof(struct f2fs_sb_info), GFP_KERNEL);
>> @@ -578,8 +577,16 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>> mutex_init(&sbi->gc_mutex);
>> mutex_init(&sbi->writepages);
>> mutex_init(&sbi->cp_mutex);
>> - for (i = 0; i < NR_GLOBAL_LOCKS; i++)
>> - mutex_init(&sbi->fs_lock[i]);
>> +
> you can try barrier() or mb() to avoid compile optimization.
>
Hi,
They aren't work!But thanks very much!

Thanks!
Jianpeng Ma


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