From 4ed7c92d68a5387ba5f7030dc76eab03558e27f5 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 23 Nov 2009 11:37:29 +0100 Subject: perf_events: Undo some recursion damage Make perf_swevent_get_recursion_context return a context number and disable preemption. This could be used to remove the IRQ disable from the trace bit and index the per-cpu buffer with. Signed-off-by: Peter Zijlstra Cc: Frederic Weisbecker Cc: Paul Mackerras LKML-Reference: <20091123103819.993226816@chello.nl> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 71 ++++++++++++++++++++++++----------------------------- 1 file changed, 32 insertions(+), 39 deletions(-) (limited to 'kernel/perf_event.c') diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 50f11b5f8c3d..0b0d5f72fe7d 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3869,45 +3869,50 @@ static void perf_swevent_ctx_event(struct perf_event_context *ctx, } } -/* - * Must be called with preemption disabled - */ -int perf_swevent_get_recursion_context(int **recursion) +int perf_swevent_get_recursion_context(void) { - struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); + struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context); + int rctx; if (in_nmi()) - *recursion = &cpuctx->recursion[3]; + rctx = 3; else if (in_irq()) - *recursion = &cpuctx->recursion[2]; + rctx = 2; else if (in_softirq()) - *recursion = &cpuctx->recursion[1]; + rctx = 1; else - *recursion = &cpuctx->recursion[0]; + rctx = 0; - if (**recursion) + if (cpuctx->recursion[rctx]) { + put_cpu_var(perf_cpu_context); return -1; + } - (**recursion)++; + cpuctx->recursion[rctx]++; + barrier(); - return 0; + return rctx; } EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context); -void perf_swevent_put_recursion_context(int *recursion) +void perf_swevent_put_recursion_context(int rctx) { - (*recursion)--; + struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); + barrier(); + cpuctx->recursion[rctx]++; + put_cpu_var(perf_cpu_context); } EXPORT_SYMBOL_GPL(perf_swevent_put_recursion_context); -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) +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) { + struct perf_cpu_context *cpuctx; struct perf_event_context *ctx; - struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); + cpuctx = &__get_cpu_var(perf_cpu_context); rcu_read_lock(); perf_swevent_ctx_event(&cpuctx->ctx, type, event_id, nr, nmi, data, regs); @@ -3921,34 +3926,22 @@ static void __do_perf_sw_event(enum perf_type_id type, u32 event_id, rcu_read_unlock(); } -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) -{ - int *recursion; - - preempt_disable(); - - if (perf_swevent_get_recursion_context(&recursion)) - goto out; - - __do_perf_sw_event(type, event_id, nr, nmi, data, regs); - - perf_swevent_put_recursion_context(recursion); -out: - preempt_enable(); -} - void __perf_sw_event(u32 event_id, u64 nr, int nmi, struct pt_regs *regs, u64 addr) { struct perf_sample_data data; + int rctx; + + rctx = perf_swevent_get_recursion_context(); + if (rctx < 0) + return; data.addr = addr; data.raw = NULL; do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs); + + perf_swevent_put_recursion_context(rctx); } static void perf_swevent_read(struct perf_event *event) @@ -4172,7 +4165,7 @@ void perf_tp_event(int event_id, u64 addr, u64 count, void *record, regs = task_pt_regs(current); /* Trace events already protected against recursion */ - __do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1, + do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1, &data, regs); } EXPORT_SYMBOL_GPL(perf_tp_event); -- cgit v1.2.2