# Re: \[PATCH v5 1/2\] tpm: add sysfs exports for all banks of PCR registers

- From: James Bottomley \<James.Bottomley@HansenPartnership.com\>
- Date: 2021-01-15 21:07:01 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2021/01/13329999
- Thread: https://ratatoskr.run/linux-integrity/2021/01/13329981/t.md

```text
On Fri, 2021-01-15 at 12:48 -0800, Joe Perches wrote:
> On Fri, 2021-01-15 at 10:07 -0800, James Bottomley wrote:
> > On Fri, 2021-01-15 at 09:26 -0800, James Bottomley wrote:
> > > On Fri, 2021-01-15 at 14:54 +0100, Greg KH wrote:
> > > > On Thu, Jan 14, 2021 at 04:21:08PM -0800, James Bottomley
> > > > wrote:
> > > [...]
> > > > > It looks like we already have a couple of bugs in the kernel
> > > > > introduced by this confusion ...  return sysfs_emit() vs
> > > > > return
> > > > > sysfs_emit_at() being the most tricky ...
> > > > 
> > > > Hm, Joe, you did the conversion to these functions (and wrote
> > > > the
> > > > api), care to review this?
> > > 
> > > A cursory glance tells me that summary_show in 
> > > drivers/infiniband/hw/usnic/usnic_ib_sysfs.c has a problem, I
> > > think the last = should be +=
> 
> No, it's correct and overwriting what would otherwise be a trailing
> space.

The last two lines of summary_show() are

   len = sysfs_emit_at(buf, len, "\n");

   return len;

So that always returns 2: the length of "\n", rather than the length of
everything you just put into buf, which is what sysfs attributes are
supposed to return.

James


```