From 11a3122f6cf2d988a77eb8883d0fc49cd013a6d5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 7 Feb 2012 07:51:30 +0100 Subject: block: strip out locking optimization in put_io_context() put_io_context() performed a complex trylock dancing to avoid deferring ioc release to workqueue. It was also broken on UP because trylock was always assumed to succeed which resulted in unbalanced preemption count. While there are ways to fix the UP breakage, even the most pathological microbench (forced ioc allocation and tight fork/exit loop) fails to show any appreciable performance benefit of the optimization. Strip it out. If there turns out to be workloads which are affected by this change, simpler optimization from the discussion thread can be applied later. Signed-off-by: Tejun Heo LKML-Reference: <1328514611.21268.66.camel@sli10-conroe> Signed-off-by: Jens Axboe --- kernel/fork.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 051f090d40c..c574aefa8d1 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -890,7 +890,7 @@ static int copy_io(unsigned long clone_flags, struct task_struct *tsk) return -ENOMEM; new_ioc->ioprio = ioc->ioprio; - put_io_context(new_ioc, NULL); + put_io_context(new_ioc); } #endif return 0; -- cgit v1.2.3-70-g09d2 From f39d47ff819ed52a2afbdbecbe35f23f7755f58d Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Tue, 7 Feb 2012 14:39:57 +0100 Subject: perf: Fix double start/stop in x86_pmu_start() The following patch fixes a bug introduced by the following commit: e050e3f0a71b ("perf: Fix broken interrupt rate throttling") The patch caused the following warning to pop up depending on the sampling frequency adjustments: ------------[ cut here ]------------ WARNING: at arch/x86/kernel/cpu/perf_event.c:995 x86_pmu_start+0x79/0xd4() It was caused by the following call sequence: perf_adjust_freq_unthr_context.part() { stop() if (delta > 0) { perf_adjust_period() { if (period > 8*...) { stop() ... start() } } } start() } Which caused a double start and a double stop, thus triggering the assert in x86_pmu_start(). The patch fixes the problem by avoiding the double calls. We pass a new argument to perf_adjust_period() to indicate whether or not the event is already stopped. We can't just remove the start/stop from that function because it's called from __perf_event_overflow where the event needs to be reloaded via a stop/start back-toback call. The patch reintroduces the assertion in x86_pmu_start() which was removed by commit: 84f2b9b ("perf: Remove deprecated WARN_ON_ONCE()") In this second version, we've added calls to disable/enable PMU during unthrottling or frequency adjustment based on bug report of spurious NMI interrupts from Eric Dumazet. Reported-and-tested-by: Eric Dumazet Signed-off-by: Stephane Eranian Acked-by: Peter Zijlstra Cc: markus@trippelsdorf.de Cc: paulus@samba.org Link: http://lkml.kernel.org/r/20120207133956.GA4932@quad [ Minor edits to the changelog and to the code ] Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 3 +++ kernel/events/core.c | 19 ++++++++++++++----- 2 files changed, 17 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 2a30e5ae6ac..5adce1040b1 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -986,6 +986,9 @@ static void x86_pmu_start(struct perf_event *event, int flags) struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); int idx = event->hw.idx; + if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED))) + return; + if (WARN_ON_ONCE(idx == -1)) return; diff --git a/kernel/events/core.c b/kernel/events/core.c index ba36013cfb2..1b5c081d8b9 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2303,7 +2303,7 @@ do { \ static DEFINE_PER_CPU(int, perf_throttled_count); static DEFINE_PER_CPU(u64, perf_throttled_seq); -static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count) +static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count, bool disable) { struct hw_perf_event *hwc = &event->hw; s64 period, sample_period; @@ -2322,9 +2322,13 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count) hwc->sample_period = sample_period; if (local64_read(&hwc->period_left) > 8*sample_period) { - event->pmu->stop(event, PERF_EF_UPDATE); + if (disable) + event->pmu->stop(event, PERF_EF_UPDATE); + local64_set(&hwc->period_left, 0); - event->pmu->start(event, PERF_EF_RELOAD); + + if (disable) + event->pmu->start(event, PERF_EF_RELOAD); } } @@ -2350,6 +2354,7 @@ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, return; raw_spin_lock(&ctx->lock); + perf_pmu_disable(ctx->pmu); list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { if (event->state != PERF_EVENT_STATE_ACTIVE) @@ -2381,13 +2386,17 @@ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, /* * restart the event * reload only if value has changed + * we have stopped the event so tell that + * to perf_adjust_period() to avoid stopping it + * twice. */ if (delta > 0) - perf_adjust_period(event, period, delta); + perf_adjust_period(event, period, delta, false); event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0); } + perf_pmu_enable(ctx->pmu); raw_spin_unlock(&ctx->lock); } @@ -4562,7 +4571,7 @@ static int __perf_event_overflow(struct perf_event *event, hwc->freq_time_stamp = now; if (delta > 0 && delta < 2*TICK_NSEC) - perf_adjust_period(event, delta, hwc->last_period); + perf_adjust_period(event, delta, hwc->last_period, true); } /* -- cgit v1.2.3-70-g09d2 From f6302f1bcd75a042df69866d98b8d775a668f8f1 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 10 Feb 2012 09:03:58 +0100 Subject: relay: prevent integer overflow in relay_open() "subbuf_size" and "n_subbufs" come from the user and they need to be capped to prevent an integer overflow. Signed-off-by: Dan Carpenter Cc: stable@kernel.org Signed-off-by: Jens Axboe --- kernel/relay.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/relay.c b/kernel/relay.c index 4335e1d7ee2..ab56a1764d4 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -164,10 +164,14 @@ depopulate: */ static struct rchan_buf *relay_create_buf(struct rchan *chan) { - struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); - if (!buf) + struct rchan_buf *buf; + + if (chan->n_subbufs > UINT_MAX / sizeof(size_t *)) return NULL; + buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); + if (!buf) + return NULL; buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); if (!buf->padding) goto free_buf; @@ -574,6 +578,8 @@ struct rchan *relay_open(const char *base_filename, if (!(subbuf_size && n_subbufs)) return NULL; + if (subbuf_size > UINT_MAX / n_subbufs) + return NULL; chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); if (!chan) -- cgit v1.2.3-70-g09d2 From 10f296cbfe3b93188c41463fd7a53808ebdbcbe3 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Wed, 1 Feb 2012 10:33:11 +0800 Subject: module: make module param bint handle nul value Allow bint param accept nul values, just do same as bool param. Signed-off-by: Dave Young Cc: Rusty Russell Signed-off-by: Rusty Russell --- kernel/params.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/params.c b/kernel/params.c index 32ee0430828..4bc965d8a1f 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -97,7 +97,8 @@ static int parse_one(char *param, for (i = 0; i < num_params; i++) { if (parameq(param, params[i].name)) { /* No one handled NULL, so do it here. */ - if (!val && params[i].ops->set != param_set_bool) + if (!val && params[i].ops->set != param_set_bool + && params[i].ops->set != param_set_bint) return -EINVAL; pr_debug("They are equal! Calling %p\n", params[i].ops->set); -- cgit v1.2.3-70-g09d2