Re: [RFC][PATCH 01/12 v3] x86/kvm/tracing: Use helper function trace_seq_buffer_ptr()

[Rustad, Mark D]

On Nov 4, 2014, at 7:52 AM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
> 
> 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@xxxxxxxxx>
> Cc: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
> 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.

> 	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

-- 
Mark Rustad, Networking Division, Intel Corporation

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