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McKenney" , Steven Rostedt , Thomas Gleixner , Sebastian Andrzej Siewior , Juri Lelli , Daniel Bristot de Oliveira , Marcelo Tosatti , Frederic Weisbecker , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Marc Zyngier , Mark Rutland , Russell King , Nicholas Piggin , "David S. Miller" Subject: Re: [RFC PATCH v2 6/8] treewide: Trace IPIs sent via smp_send_reschedule() In-Reply-To: References: <20221102182949.3119584-1-vschneid@redhat.com> <20221102183336.3120536-5-vschneid@redhat.com> Date: Thu, 17 Nov 2022 14:24:04 +0000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/11/22 10:12, Peter Zijlstra wrote: > On Wed, Nov 02, 2022 at 06:33:34PM +0000, Valentin Schneider wrote: > >> diff --git a/kernel/smp.c b/kernel/smp.c >> index c4d561cf50d45..44fa4b9b1f46b 100644 >> --- a/kernel/smp.c >> +++ b/kernel/smp.c >> @@ -167,6 +167,14 @@ send_call_function_ipi_mask(const struct cpumask *mask) >> arch_send_call_function_ipi_mask(mask); >> } >> >> +void smp_send_reschedule(int cpu) >> +{ >> + /* XXX scheduler_ipi is inline :/ */ >> + trace_ipi_send_cpumask(cpumask_of(cpu), _RET_IP_, NULL); >> + arch_smp_send_reschedule(cpu); >> +} >> +EXPORT_SYMBOL_GPL(smp_send_reschedule); > > Yeah, no.. I see some crazy archs do this, but no we're not exporting > this in generic. So the list is: ia64, powerpc, riscv and they all seem to do it because of KVM: c4cb768f0277 ("[IA64] export smp_send_reschedule") de56a948b918 ("KVM: PPC: Add support for Book3S processors in hypervisor mode") d3d7a0ce020e ("RISC-V: Export kernel symbols for kvm") Other archs get out of it either because their smp_send_reschedule() is inline (e.g. x86), or because they don't allow building KVM as a module (e.g. arm64). If I can cobble the tracepoint+reschedule in an inline helper, then that wouldn't require any new exports - I'm fighting a bit with the header maze ATM, but hopefully I can get somewhere with this.