On Sat, Oct 01, 2016 at 10:32:39PM +0300, Jarkko Sakkinen wrote:
> On Sat, Oct 01, 2016 at 10:54:36AM -0600, Jason Gunthorpe wrote:
> > On Sat, Oct 01, 2016 at 03:01:25PM +0300, Jarkko Sakkinen wrote:
> >
> > > > + struct tpmfs_data bin_sfs_data;
> > > > + struct tpmfs_data ascii_sfs_data;
> > >
> > > I think this is otherwise right but the struct name is very clunky.
> > > First of all it doesn't own the data and IMHO now it kind of implies
> > > of owning.
>
> Ok, I'm not going to make this an issue. If you think these are good
> names, I'll live with that :)
>
> > These are passed in here:
> >
> > > > chip->bios_dir[chip->bios_dir_count] =
> > > > securityfs_create_file("ascii_bios_measurements",
> > > > S_IRUSR | S_IRGRP, chip->bios_dir[0],
> > > > - (void
> > > > *)&tpm_ascii_b_measurments_seqops,
> > > > + (void *)&chip->ascii_sfs_data,
> > > > &tpm_bios_measurements_ops);
> >
> > And the argument to securityfs_create_file is called 'data'..
> >
> > The key question with these patches is if all the locking is done
> > right and we have the correct lifetime model now.
> >
> > Eg how much does securityfs_remove serialize and is the kref on the
> > chip held for the duration of any fops. Can open() start after the
> > kref is dropped, etc.
>
> Why not make tpmfs_data refcounted in order to remove
> binding to the chip?
Data type could be something like
struct tpmfs_data {
struct tpm_bios_log log;
const struct seq_operations *seqops;
struct kref refcount;
};
void tpmfs_data_release(struct kref *ref)
{
struct tpmfs_data *data =
container_of(ref, struct tpmfs_data, refcount);
kfree(data->bios_event_log);
kfree(data);
}
In tpm_bios_log_setup:
chip->tpmfs_data = kzalloc(sizeof(*chip->tpmfs_data));
kref_init(&chip->tpmfs_data->refcount);
Then use kref_get() in open and kref_put() in close and finally
kref_put() in tpm_bios_log_teardown.
If the chip is destroyed while the file is still open the event log data
would be still alive.
/Jarkko
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