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Commit 39e38362 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull perf fixes from Thomas Gleixner:
 "Four patches which all address lock inversions and deadlocks in the
  perf core code and the Intel debug store"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: Fix perf,x86,cpuhp deadlock
  perf/core: Fix ctx::mutex deadlock
  perf/core: Fix another perf,trace,cpuhp lock inversion
  perf/core: Fix lock inversion between perf,trace,cpuhp
parents 8c76e31a efe951d3

arch/x86/events/intel/ds.c

+18 −15
Original line number Diff line number Diff line
@@ -372,10 +372,9 @@ static int alloc_pebs_buffer(int cpu) 
static void release_pebs_buffer(int cpu)

{

	struct cpu_hw_events *hwev = per_cpu_ptr(&cpu_hw_events, cpu);

	struct debug_store *ds = hwev->ds;

	void *cea;



	if (!ds || !x86_pmu.pebs)

	if (!x86_pmu.pebs)

		return;



	kfree(per_cpu(insn_buffer, cpu));
@@ -384,7 +383,6 @@ static void release_pebs_buffer(int cpu) 
	/* Clear the fixmap */

	cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.pebs_buffer;

	ds_clear_cea(cea, x86_pmu.pebs_buffer_size);

	ds->pebs_buffer_base = 0;

	dsfree_pages(hwev->ds_pebs_vaddr, x86_pmu.pebs_buffer_size);

	hwev->ds_pebs_vaddr = NULL;

}
@@ -419,16 +417,14 @@ static int alloc_bts_buffer(int cpu) 
static void release_bts_buffer(int cpu)

{

	struct cpu_hw_events *hwev = per_cpu_ptr(&cpu_hw_events, cpu);

	struct debug_store *ds = hwev->ds;

	void *cea;



	if (!ds || !x86_pmu.bts)

	if (!x86_pmu.bts)

		return;



	/* Clear the fixmap */

	cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.bts_buffer;

	ds_clear_cea(cea, BTS_BUFFER_SIZE);

	ds->bts_buffer_base = 0;

	dsfree_pages(hwev->ds_bts_vaddr, BTS_BUFFER_SIZE);

	hwev->ds_bts_vaddr = NULL;

}
@@ -454,16 +450,22 @@ void release_ds_buffers(void) 
	if (!x86_pmu.bts && !x86_pmu.pebs)

		return;



	get_online_cpus();

	for_each_online_cpu(cpu)

	for_each_possible_cpu(cpu)

		release_ds_buffer(cpu);



	for_each_possible_cpu(cpu) {

		/*

		 * Again, ignore errors from offline CPUs, they will no longer

		 * observe cpu_hw_events.ds and not program the DS_AREA when

		 * they come up.

		 */

		fini_debug_store_on_cpu(cpu);

	}



	for_each_possible_cpu(cpu) {

		release_pebs_buffer(cpu);

		release_bts_buffer(cpu);

		release_ds_buffer(cpu);

	}

	put_online_cpus();

}



void reserve_ds_buffers(void)
@@ -483,8 +485,6 @@ void reserve_ds_buffers(void) 
	if (!x86_pmu.pebs)

		pebs_err = 1;



	get_online_cpus();



	for_each_possible_cpu(cpu) {

		if (alloc_ds_buffer(cpu)) {

			bts_err = 1;
@@ -521,11 +521,14 @@ void reserve_ds_buffers(void) 
		if (x86_pmu.pebs && !pebs_err)

			x86_pmu.pebs_active = 1;



		for_each_online_cpu(cpu)

		for_each_possible_cpu(cpu) {

			/*

			 * Ignores wrmsr_on_cpu() errors for offline CPUs they

			 * will get this call through intel_pmu_cpu_starting().

			 */

			init_debug_store_on_cpu(cpu);

		}



	put_online_cpus();

	}

}



/*

kernel/events/core.c

+42 −5
Original line number Diff line number Diff line
@@ -1231,6 +1231,10 @@ static void put_ctx(struct perf_event_context *ctx) 
 *	      perf_event_context::lock

 *	    perf_event::mmap_mutex

 *	    mmap_sem

 *

 *    cpu_hotplug_lock

 *      pmus_lock

 *	  cpuctx->mutex / perf_event_context::mutex

 */

static struct perf_event_context *

perf_event_ctx_lock_nested(struct perf_event *event, int nesting)
@@ -4196,6 +4200,7 @@ int perf_event_release_kernel(struct perf_event *event) 
{

	struct perf_event_context *ctx = event->ctx;

	struct perf_event *child, *tmp;

	LIST_HEAD(free_list);



	/*

	 * If we got here through err_file: fput(event_file); we will not have
@@ -4268,8 +4273,7 @@ int perf_event_release_kernel(struct perf_event *event) 
					       struct perf_event, child_list);

		if (tmp == child) {

			perf_remove_from_context(child, DETACH_GROUP);

			list_del(&child->child_list);

			free_event(child);

			list_move(&child->child_list, &free_list);

			/*

			 * This matches the refcount bump in inherit_event();

			 * this can't be the last reference.
@@ -4284,6 +4288,11 @@ int perf_event_release_kernel(struct perf_event *event) 
	}

	mutex_unlock(&event->child_mutex);



	list_for_each_entry_safe(child, tmp, &free_list, child_list) {

		list_del(&child->child_list);

		free_event(child);

	}



no_ctx:

	put_event(event); /* Must be the 'last' reference */

	return 0;
@@ -8516,6 +8525,29 @@ perf_event_set_addr_filter(struct perf_event *event, char *filter_str) 
	return ret;

}



static int

perf_tracepoint_set_filter(struct perf_event *event, char *filter_str)

{

	struct perf_event_context *ctx = event->ctx;

	int ret;



	/*

	 * Beware, here be dragons!!

	 *

	 * the tracepoint muck will deadlock against ctx->mutex, but the tracepoint

	 * stuff does not actually need it. So temporarily drop ctx->mutex. As per

	 * perf_event_ctx_lock() we already have a reference on ctx.

	 *

	 * This can result in event getting moved to a different ctx, but that

	 * does not affect the tracepoint state.

	 */

	mutex_unlock(&ctx->mutex);

	ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);

	mutex_lock(&ctx->mutex);



	return ret;

}



static int perf_event_set_filter(struct perf_event *event, void __user *arg)

{

	char *filter_str;
@@ -8532,8 +8564,7 @@ static int perf_event_set_filter(struct perf_event *event, void __user *arg) 


	if (IS_ENABLED(CONFIG_EVENT_TRACING) &&

	    event->attr.type == PERF_TYPE_TRACEPOINT)

		ret = ftrace_profile_set_filter(event, event->attr.config,

						filter_str);

		ret = perf_tracepoint_set_filter(event, filter_str);

	else if (has_addr_filter(event))

		ret = perf_event_set_addr_filter(event, filter_str);
@@ -9168,7 +9199,13 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) 
	if (!try_module_get(pmu->module))

		return -ENODEV;



	if (event->group_leader != event) {

	/*

	 * A number of pmu->event_init() methods iterate the sibling_list to,

	 * for example, validate if the group fits on the PMU. Therefore,

	 * if this is a sibling event, acquire the ctx->mutex to protect

	 * the sibling_list.

	 */

	if (event->group_leader != event && pmu->task_ctx_nr != perf_sw_context) {

		/*

		 * This ctx->mutex can nest when we're called through

		 * inheritance. See the perf_event_ctx_lock_nested() comment.