On Nov 4, 2014, at 11:35 AM, Steven Rostedt <[email protected]> wrote:
> On Tue, 4 Nov 2014 14:09:54 -0500 > Steven Rostedt <[email protected]> wrote: > >> On Tue, 4 Nov 2014 17:17:08 +0000 >> "Rustad, Mark D" <[email protected]> wrote: >> >>> On Nov 4, 2014, at 7:52 AM, Steven Rostedt <[email protected]> wrote: >>> >>>> From: "Steven Rostedt (Red Hat)" <[email protected]> >>>> >>>> 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 <[email protected]> >>>> Cc: Jeff Kirsher <[email protected]> >>>> Cc: Paolo Bonzini <[email protected]> >>>> Signed-off-by: Steven Rostedt <[email protected]> >>>> --- >>>> 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. At least not by the caller of the macro. The subsequent call to trace_seq_printf will be changing the contents at that address, but not through use of that pointer. > 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. Agreed. > This patch is good as is. It should not be a char *, or char * const. Yes. I did further checking and agree. Although that memory will be written, it isn't written through that pointer and it is the best type as a return value. > -- 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 >>> >> > Acked-by: Mark Rustad <[email protected]> -- Mark Rustad, Networking Division, Intel Corporation
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