On Fri, Jan 18, 2013 at 01:45:27PM -0800, Greg Kroah-Hartman wrote: > On Fri, Jan 18, 2013 at 09:08:59PM +0000, Russell King - ARM Linux wrote: > > On Fri, Jan 18, 2013 at 02:24:15PM -0600, Matt Sealey wrote: > > > Hello all, > > > > > > I wonder if anyone can shed some light on this linking problem I have > > > right now. If I configure my kernel without SMP support (it is a very > > > lean config for i.MX51 with device tree support only) I hit this error > > > on linking: > > > > Yes, I looked at this, and I've decided that I will _not_ fix this export, > > neither will I accept a patch to add an export. > > > > As far as I can see, this code is buggy in a SMP environment. There's > > apparantly no guarantee that: > > > > 1. the mapping will be created on a particular CPU. > > 2. the mapping will then be used only on this specific CPU. > > 3. no guarantee that another CPU won't speculatively prefetch from this > > region. I thought the code had per_cpu for it - so that you wouldn't do that unless you really went out the way to do it. > > 4. when the mapping is torn down, no guarantee that it's the same CPU that > > used the happing. With per_cpu that actually would be the case. > > > > So, the use of the local TLB flush leaves all the other CPUs potentially > > containing TLB entries for this mapping. Right. That is the point of a local TLB flush. > > > > Finally, there is no TODO file for this driver, which I believe is a > > requirement for anything to be in stable. So as far as I can see, it > > should be deleted or a TODO file added. I'm not sure why Greg decided > > to add it without a TODO file. A TODO file can certainly be added and it is welcome. > > I don't know, I'm cursing the day I took the whole zsmalloc, zcache, > zram mess that we have in the staging tree now. People are working to > get them out of staging, which is good, but the churn involved is > driving me crazy. Oh oh. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
