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SubjectRe: [PATCH 4/6] sysfs: use sysfs_lock to protect the sysfs_dirent tree
Cornelia Huck wrote:
> On Tue, 29 May 2007 01:36:27 +0900,
> Tejun Heo <htejun@gmail.com> wrote:
>
>> @@ -795,6 +822,8 @@ static int sysfs_readdir(struct file * f
>> i++;
>> /* fallthrough */
>> default:
>> + spin_lock(&sysfs_lock);
>> +
>> pos = &parent_sd->s_children;
>> while (*pos != cursor)
>> pos = &(*pos)->s_sibling;
>> @@ -827,6 +856,8 @@ static int sysfs_readdir(struct file * f
>> /* put cursor back in */
>> cursor->s_sibling = *pos;
>> *pos = cursor;
>> +
>> + spin_unlock(&sysfs_lock);
>> }
>> return 0;
>> }
>
> Here's the cause of the "sleeping function called" I saw. filldir() is
> called under sysfs_lock, but calls copy_to_user()... This means you
> can't use sysfs_lock for protection here.

Ouch, right. I think we can get away with a temp buffer there. Thanks.

--
tejun
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