Messages in this thread | | | Date | Tue, 4 Nov 2014 14:35:38 -0500 | From | Steven Rostedt <> | Subject | Re: [RFC][PATCH 01/12 v3] x86/kvm/tracing: Use helper function trace_seq_buffer_ptr() |
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On Tue, 4 Nov 2014 14:09:54 -0500 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Tue, 4 Nov 2014 17:17:08 +0000 > "Rustad, Mark D" <mark.d.rustad@intel.com> wrote: > > > On Nov 4, 2014, at 7:52 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > > > > > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org> > > > > > > To allow for the restructiong of the trace_seq code, we need users > > > of it to use the helper functions instead of accessing the internals > > > of the trace_seq structure itself. > > > > > > Cc: Mark Rustad <mark.d.rustad@intel.com> > > > Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> > > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > > Signed-off-by: Steven Rostedt <rostedt@goodmis.org> > > > --- > > > arch/x86/kvm/mmutrace.h | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h > > > index 5aaf35641768..ce463a9cc8fb 100644 > > > --- a/arch/x86/kvm/mmutrace.h > > > +++ b/arch/x86/kvm/mmutrace.h > > > @@ -22,7 +22,7 @@ > > > __entry->unsync = sp->unsync; > > > > > > #define KVM_MMU_PAGE_PRINTK() ({ \ > > > - const u32 saved_len = p->len; \ > > > + const char *saved_ptr = trace_seq_buffer_ptr(p); \ > > > > I think the above should not be a const char *, because the location pointed to is surely being changed. It should either be a char * or a char * const. > > Ah right. It should be 'char * const'. >
Actually, I take that back. The contents of saved_ptr should not be modified.
It may seem strange, but the update is done via the trace_seq_printf(). Then that content is return back to the user. The user should definitely *not* modify the contents of saved_ptr.
This patch is good as is. It should not be a char *, or char * const.
-- Steve
> > > > > > static const char *access_str[] = { \ > > > "---", "--x", "w--", "w-x", "-u-", "-ux", "wu-", "wux" \ > > > }; \ > > > @@ -41,7 +41,7 @@ > > > role.nxe ? "" : "!", \ > > > __entry->root_count, \ > > > __entry->unsync ? "unsync" : "sync", 0); \ > > > - p->buffer + saved_len; \ > > > + saved_ptr; \ > > > }) > > > > > > #define kvm_mmu_trace_pferr_flags \ > > > -- > > > 2.1.1 > > >
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