On Oct 13,  2:36am, simonb@wasabisystems.com (Simon Burge) wrote:
-- Subject: Re: kern/31430: ptyfs isn't getting mtime right

| YAMAMOTO Takashi wrote:
| 
| > > The patch below is a result of a discussion off-line with Christos.
| > > The granularity of the mtime doesn't need to be down to the nanosecond
| > > - using the kernel "time" variable (which is updated on each
| > > hardclock call) saves a potentially relatively expensive call to
| > > microtime/nanotime for each write, and is more than accurate enough to
| > > track pty idle times.
| > 
| > it isn't good to mix "time" and nanotime
| > because it can make timestamps go backward sometimes.
| 
| You're suggesting that ptyfs_itimes() use "time" as well if any of the
| timespec pointers are NULL then?  Or a different solution?

He is saying that there are other callers of ptyfs_itime() that call it
with nanotime() or NULL, so the results can be inconsistent. I don't think
that this is very important in this case (considering that ptyfs is not
even enabled by default, and right now times are completely off). I do
think that we should work towards making everything in the kernel use
timespecs, so that we don't have this problem.

christos