From b58f6b0dd3d677338b9065388cc2cc942b86338e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 7 Jun 2011 00:23:28 +0200 Subject: [PATCH] perf, core: Fix initial task_ctx/event installation A lost Quilt refresh of 2c29ef0fef8 (perf: Simplify and fix __perf_install_in_context()) is causing grief and lockups, reported by Jiri Olsa. When installing an event in a task context, there's a number of issues: - there might not be an existing task context, in which case we should install the now current context; - there might already be a context, not the current one, in which case we should de-schedule the old and install the new; these cases were dealt with in the lost refresh, however there is one further case that was found in testing: - there might already be a context, the current one, in which case we should still de-schedule, and should take care to re-install it (note that task_ctx_sched_out() clears cpuctx->task_ctx). Reported-by: Jiri Olsa Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1307399008.2497.971.camel@laptop Signed-off-by: Ingo Molnar --- kernel/events/core.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index ba89f40abe6a..5e8c7b1389bc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1505,25 +1505,31 @@ static int __perf_install_in_context(void *info) struct perf_event_context *task_ctx = cpuctx->task_ctx; struct task_struct *task = current; - perf_ctx_lock(cpuctx, cpuctx->task_ctx); + perf_ctx_lock(cpuctx, task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); /* * If there was an active task_ctx schedule it out. */ - if (task_ctx) { + if (task_ctx) task_ctx_sched_out(task_ctx); - /* - * If the context we're installing events in is not the - * active task_ctx, flip them. - */ - if (ctx->task && task_ctx != ctx) { - raw_spin_unlock(&cpuctx->ctx.lock); - raw_spin_lock(&ctx->lock); - cpuctx->task_ctx = task_ctx = ctx; - } + + /* + * If the context we're installing events in is not the + * active task_ctx, flip them. + */ + if (ctx->task && task_ctx != ctx) { + if (task_ctx) + raw_spin_unlock(&task_ctx->lock); + raw_spin_lock(&ctx->lock); + task_ctx = ctx; + } + + if (task_ctx) { + cpuctx->task_ctx = task_ctx; task = task_ctx->task; } + cpu_ctx_sched_out(cpuctx, EVENT_ALL); update_context_time(ctx); -- 2.34.1