Messages in this thread | | | Date | Wed, 18 Jul 2007 22:19:20 +0530 | From | "Satyam Sharma" <> | Subject | Re: [PATCH] sysfs: kill an extra put in sysfs_create_link() failure path |
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On 7/18/07, Tejun Heo <htejun@gmail.com> wrote: > Tejun Heo wrote: > > Satyam Sharma wrote: > >>>> sysfs_find_dirent() -- to check for -EEXIST -- should be called > >>>> *before* we create the new dentry for the to-be-created symlink > >>>> in the first place. [ It's weird to grab a reference on the target > >>>> for ourselves (and in fact even allocate the new dirent for the > >>>> to-be-created symlink) and /then/ check for erroneous usage, > >>>> and then go about undoing all that we should never have done > >>>> at all. ] So this test could, and should, be made earlier, IMHO. > >>> Locking. > >> Well s/sysfs_find_dirent/sysfs_get_dirent/ then. And then simply put > >> down the reference later. > > > > Isn't that the current code? > > Oops, somehow thought you were talking about allocating it first. > Gee... what difference does using sysfs_get_dirent() make? Do you think > the following code is correct? > > sd = sysfs_get_dirent("some name"); > if (sd != NULL) > return -EEXIST; > lock; > add_new_node("some name"); > unlock; > sysfs_put_dirent(sd);
Nopes, it's not, of course. We'd need the parent's i_mutex as well as the sysfs_mutex around both the EEXIST check as well as the actual sysfs_add_one(), which is precisely what sysfs_addrm_start and finish are, so you're right ... I'll factor this in.
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