<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Oct 31, 2013 at 8:51 AM, William Roberts <span dir="ltr"><<a href="mailto:bill.c.roberts@gmail.com" target="_blank">bill.c.roberts@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div class="h5">On Thu, Oct 31, 2013 at 8:46 AM, Richard Guy Briggs <span dir="ltr"><<a href="mailto:rgb@redhat.com" target="_blank">rgb@redhat.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div>On Thu, Oct 31, 2013 at 08:33:34AM -0700, William Roberts wrote:<br>
> On Thu, Oct 31, 2013 at 8:28 AM, Richard Guy Briggs <<a href="mailto:rgb@redhat.com" target="_blank">rgb@redhat.com</a>> wrote:<br>
><br>
> > On Thu, Oct 31, 2013 at 08:24:11AM -0700, William Roberts wrote:<br>
> > > On Thu, Oct 31, 2013 at 7:36 AM, Steve Grubb <<a href="mailto:sgrubb@redhat.com" target="_blank">sgrubb@redhat.com</a>> wrote:<br>
> > > > On Wednesday, October 30, 2013 01:18:13 PM William Roberts wrote:<br>
> > > > > On Wed, Oct 30, 2013 at 12:42 PM, Steve Grubb <<a href="mailto:sgrubb@redhat.com" target="_blank">sgrubb@redhat.com</a>> wrote:<br>
> > > > > I have compiled kernels in the past with custom COMM widths, but<br>
> > > > > the memory footprint goes up, at least here were not keeping a<br>
> > > > > bunch of possibly unused data around in the kernel plus we're not<br>
> > > > > allocating anything on the common case of it being turned off.<br>
> > > ><br>
> > > > I don't like the idea of fields appearing and disappearing. The<br>
> > > > complaint is "comm" is meaningless. Let's fix that.<br>
> > ><br>
> > > Its not that the field is disappearing, its just whether or not you<br>
> > > want the value printed out. cmdline=(null) vs cmdline="something".<br>
> > > That's a trivial change of not making it dynamic which is what my<br>
> > > first patch did but Richard Briggs suggested making it a dynamic<br>
> > > feature and I was pretty ok with that.<br>
> ><br>
> > Ok, so how about both fields are always present, but have some keyword<br>
> > that is printed that indicates it is a duplicate of the other field?<br>
> ><br>
> > Something like cmdline=(comm)<br>
><br>
> How are you going to detect that cmdlne has changed, its a region of<br>
> memory in userspace? We would have to cmp the values, and if we cannot<br>
> detect the transition, this gets more expensive. Also, I have yet to<br>
> see a case where the above statement is true, so it would be a very<br>
> infrequent event.<br>
<br>
</div></div>Is it likely that those two point to the same region of memory? If so,<br>
just compare the pointers.<br></blockquote><div><br></div></div></div><div>no cmdline is mapped into the user process, cmdline is mapped into the kernel, so their</div><div>virtual addresses and pa's are different (hopefully or I don't understand mmu based memory management)</div>
<div class="im">
<div> </div></div></div></div></div></blockquote><div><br></div><div>Sorry incorrect above:</div><div>cmdline --> user process</div><div>comm --> Kernel process</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div class="im"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><br>
> However, their is a condition in my patch where an error will cause<br>
> comm=(null) not to be printed, which could be<br>
> viewed as a disappearing field.<br>
<br>
</div>Would it be useful if this condition were changed to print instead comm=(error)?<br></blockquote><div><br></div></div><div>It could be, but ideally we should printk the error too.... someone can arbitrarily set their</div>
<div>proc cmdline entry or tsk comm to something "reserved"</div><div class="im"><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div><br>
> > > William C Roberts<br>
> ><br>
> > - RGB<br>
><br>
> William C Roberts<br>
<br>
- RGB<br>
<br>
--<br>
Richard Guy Briggs <<a href="mailto:rbriggs@redhat.com" target="_blank">rbriggs@redhat.com</a>><br>
Senior Software Engineer<br>
Kernel Security<br>
AMER ENG Base Operating Systems<br>
Remote, Ottawa, Canada<br>
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</div></div></blockquote></div></div><br><br clear="all"><div class="im"><div><br></div>-- <br>Respectfully,<br><br>William C Roberts<br><br>
</div></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br>Respectfully,<br><br>William C Roberts<br><br>
</div></div>