Messages in this thread | | | Date | Sun, 22 Nov 2009 12:22:59 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/4] tracing: Use the perf recursion protection from trace event |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> On Sun, 2009-11-22 at 05:21 +0100, Frederic Weisbecker wrote: > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > > index 718fa93..aba8227 100644 > > --- a/kernel/perf_event.c > > +++ b/kernel/perf_event.c > > @@ -3880,34 +3880,42 @@ static void perf_swevent_ctx_event(struct perf_event_context *ctx, > > } > > } > > > > -static int *perf_swevent_recursion_context(struct perf_cpu_context *cpuctx) > > +/* > > + * Must be called with preemption disabled > > + */ > > +int perf_swevent_get_recursion_context(int **recursion) > > { > > + struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); > > + > > if (in_nmi()) > > - return &cpuctx->recursion[3]; > > + *recursion = &cpuctx->recursion[3]; > > + else if (in_irq()) > > + *recursion = &cpuctx->recursion[2]; > > + else if (in_softirq()) > > + *recursion = &cpuctx->recursion[1]; > > + else > > + *recursion = &cpuctx->recursion[0]; > > > > - if (in_irq()) > > - return &cpuctx->recursion[2]; > > + if (**recursion) > > + return -1; > > > > - if (in_softirq()) > > - return &cpuctx->recursion[1]; > > + (**recursion)++; > > > > - return &cpuctx->recursion[0]; > > + return 0; > > } > > You lost the barrier(); > > > -static void do_perf_sw_event(enum perf_type_id type, u32 event_id, > > - u64 nr, int nmi, > > - struct perf_sample_data *data, > > - struct pt_regs *regs) > > +void perf_swevent_put_recursion_context(int *recursion) > > { > > - struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context); > > - int *recursion = perf_swevent_recursion_context(cpuctx); > > - struct perf_event_context *ctx; > > - > > - if (*recursion) > > - goto out; > > + (*recursion)--; > > +} > > And here as well.
Global functions are in essence a barrier() to GCC but yeah.
Ingo
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