From: Ingo Molnar <mingo@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Borislav Petkov <bpetkov@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Rik van Riel <riel@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Nadav Amit <namit@vmware.com>, Michal Hocko <mhocko@suse.com>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [RFC 09/10] x86/mm: Rework lazy TLB to track the actual loaded mm
Date: Wed, 10 May 2017 10:24:25 +0200 [thread overview]
Message-ID: <20170510082425.5ks5okbjne7xgjtv@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1705101017590.1979@nanos>
* Thomas Gleixner <tglx@linutronix.de> wrote:
> On Wed, 10 May 2017, Ingo Molnar wrote:
> >
> > * Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > > On Sun, 7 May 2017, Andy Lutomirski wrote:
> > > > /* context.lock is held for us, so we don't need any locking. */
> > > > static void flush_ldt(void *current_mm)
> > > > {
> > > > + struct mm_struct *mm = current_mm;
> > > > mm_context_t *pc;
> > > >
> > > > - if (current->active_mm != current_mm)
> > > > + if (this_cpu_read(cpu_tlbstate.loaded_mm) != current_mm)
> > >
> > > While functional correct, this really should compare against 'mm'.
> > >
> > > > return;
> > > >
> > > > - pc = ¤t->active_mm->context;
> > > > + pc = &mm->context;
> >
> > So this appears to be the function:
> >
> > static void flush_ldt(void *current_mm)
> > {
> > struct mm_struct *mm = current_mm;
> > mm_context_t *pc;
> >
> > if (this_cpu_read(cpu_tlbstate.loaded_mm) != current_mm)
> > return;
> >
> > pc = &mm->context;
> > set_ldt(pc->ldt->entries, pc->ldt->size);
> > }
> >
> > why not rename 'current_mm' to 'mm' and remove the 'mm' local variable?
>
> Because you cannot dereference a void pointer, i.e. &mm->context ....
Indeed, doh! The naming totally confused me. The way I'd write it is the canonical
form for such callbacks:
static void flush_ldt(void *data)
{
struct mm_struct *mm = data;
... which beyond unconfusing me would probably also have prevented any accidental
use of the 'current_mm' callback argument.
Thanks,
Ingo
next prev parent reply other threads:[~2017-05-10 8:24 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-07 12:38 [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Andy Lutomirski
2017-05-07 12:38 ` [RFC 01/10] x86/mm: Reimplement flush_tlb_page() using flush_tlb_mm_range() Andy Lutomirski
2017-05-11 17:41 ` Borislav Petkov
2017-05-12 3:35 ` Andy Lutomirski
2017-05-07 12:38 ` [RFC 02/10] x86/mm: Reduce indentation in flush_tlb_func() Andy Lutomirski
2017-05-07 12:38 ` [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Andy Lutomirski
2017-05-08 15:34 ` Dave Hansen
2017-05-09 13:02 ` Andy Lutomirski
2017-05-09 14:39 ` Mel Gorman
2017-05-09 17:13 ` Dave Hansen
2017-05-09 22:54 ` Andy Lutomirski
2017-05-07 12:38 ` [RFC 04/10] x86/mm: Pass flush_tlb_info to flush_tlb_others() etc Andy Lutomirski
2017-05-11 20:01 ` Nadav Amit
2017-05-12 3:41 ` Andy Lutomirski
2017-05-07 12:38 ` [RFC 05/10] x86/mm: Change the leave_mm() condition for local TLB flushes Andy Lutomirski
2017-05-07 12:38 ` [RFC 06/10] x86/mm: Refactor flush_tlb_mm_range() to merge local and remote cases Andy Lutomirski
2017-05-07 12:38 ` [RFC 07/10] x86/mm: Use new merged flush logic in arch_tlbbatch_flush() Andy Lutomirski
2017-05-07 12:38 ` [RFC 08/10] x86/mm: Remove the UP tlbflush code; always use the formerly SMP code Andy Lutomirski
2017-05-07 12:38 ` [RFC 09/10] x86/mm: Rework lazy TLB to track the actual loaded mm Andy Lutomirski
2017-05-09 20:41 ` Thomas Gleixner
2017-05-09 22:54 ` Andy Lutomirski
2017-05-10 5:57 ` Ingo Molnar
2017-05-10 8:19 ` Thomas Gleixner
2017-05-10 8:24 ` Ingo Molnar [this message]
2017-05-10 22:42 ` Andy Lutomirski
2017-05-11 7:13 ` Ingo Molnar
2017-05-12 3:36 ` Andy Lutomirski
2017-05-07 12:38 ` [RFC 10/10] x86,kvm: Teach KVM's VMX code that CR3 isn't a constant Andy Lutomirski
2017-05-07 13:00 ` [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support Ingo Molnar
2017-05-07 16:05 ` Linus Torvalds
2017-05-08 16:36 ` Nadav Amit
2017-05-09 12:43 ` Andy Lutomirski
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