[lttng-dev] [PATCH] Fix: RHEL 7.2 kvm instrumentation

[Mohamad]

On 06/27/2016 12:13 PM, Mathieu Desnoyers wrote:
>
> ----- On Jun 27, 2016, at 11:26 AM, mo geb <mohamad.gebai at gmail.com> 
> wrote:
>
> Please use [PATCH lttng-modules] in the subject.
>
Got it.
>
>     Signed-off-by: Mohamad Gebai <mohamad.gebai at gmail.com>
>     ---
>      instrumentation/events/lttng-module/arch/x86/kvm/trace.h | 3 ++-
>      1 file changed, 2 insertions(+), 1 deletion(-)
>
>     diff --git
>     a/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
>     b/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
>     index 1282bea..ef3d8aa 100644
>     --- a/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
>     +++ b/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
>     @@ -429,7 +429,8 @@ LTTNG_TRACEPOINT_EVENT(kvm_emulate_insn,
>                     ctf_integer(__u8, len,
>     vcpu->arch.emulate_ctxt.decode.eip
>                                     -
>     vcpu->arch.emulate_ctxt.decode.fetch.start)
>                     ctf_array(__u8, insn,
>     vcpu->arch.emulate_ctxt.decode.fetch.data, 15)
>     -#elif (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0))
>     +#elif (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0) \
>     +    && !LTTNG_RHEL_KERNEL_RANGE(3,10,0,7,2, 3,11,0,0,0))
>
>
> We don't use negation "!" in kernel version range tests. We also don't use
> "&&" typically, to make the code easier to maintain.
>
> Instead, we might want to swap the order in which ifdefs are done, and put
> newer versions at the top, e.g.:
>
> #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) \
>   || LTTNG_RHEL_KERNEL_RANGE(3,10,0,7,2, 3,11,0,0,0))
> ...
> #elif (LINUX_VERSION_CODE >= KERNEL_VERSION(3,1,0))
> ...
> #else
> ...
> #endif
>
> Thanks,
>
> Mathieu
>

Thanks for the comments, I'll make those changes and resubmit. I just 
want to point out that I used a check similar to what's in 
wrapper/trace-clock.h:

#if ((LTTNG_KERNEL_RANGE(3,10,0, 3,10,14) && 
!LTTNG_RHEL_KERNEL_RANGE(3,10,0,7,0, 3,10,14,0,0)) \
     || LTTNG_KERNEL_RANGE(3,11,0, 3,11,3))
#error "Linux kernels 3.10 and 3.11 introduce a deadlock in the 
timekeeping subsystem. Fixed by commit 
7bd36014460f793c19e7d6c94dab67b0afcfcb7f \"timekeeping: Fix HRTICK 
related deadlock from ntp lock changes\" in Linux."
#endif

Mohamad

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