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

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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
This commit is contained in:
Linus Torvalds 2018-01-28 11:48:25 -08:00
commit 39e383626c
2 changed files with 60 additions and 20 deletions
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33
arch/x86/events/intel/ds.c
View File

@ -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();
}
/*

47
kernel/events/core.c
View File

@ -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 @@ again:
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 @@ again:
}
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 @@ fail_clear_files:
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.