diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 35 |
1 files changed, 26 insertions, 9 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 0d58522103cd..d7b0316e3465 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2158,13 +2158,15 @@ perf_install_in_context(struct perf_event_context *ctx, */ raw_spin_lock_irq(&ctx->lock); task = ctx->task; + /* - * Worse, we cannot even rely on the ctx actually existing anymore. If - * between find_get_context() and perf_install_in_context() the task - * went through perf_event_exit_task() its dead and we should not be - * adding new events. + * If between ctx = find_get_context() and mutex_lock(&ctx->mutex) the + * ctx gets destroyed, we must not install an event into it. + * + * This is normally tested for after we acquire the mutex, so this is + * a sanity check. */ - if (task == TASK_TOMBSTONE) { + if (WARN_ON_ONCE(task == TASK_TOMBSTONE)) { raw_spin_unlock_irq(&ctx->lock); return; } @@ -8389,10 +8391,19 @@ SYSCALL_DEFINE5(perf_event_open, if (move_group) { gctx = group_leader->ctx; mutex_lock_double(&gctx->mutex, &ctx->mutex); + if (gctx->task == TASK_TOMBSTONE) { + err = -ESRCH; + goto err_locked; + } } else { mutex_lock(&ctx->mutex); } + if (ctx->task == TASK_TOMBSTONE) { + err = -ESRCH; + goto err_locked; + } + if (!perf_event_validate_size(event)) { err = -E2BIG; goto err_locked; @@ -8563,12 +8574,14 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); + if (ctx->task == TASK_TOMBSTONE) { + err = -ESRCH; + goto err_unlock; + } + if (!exclusive_event_installable(event, ctx)) { - mutex_unlock(&ctx->mutex); - perf_unpin_context(ctx); - put_ctx(ctx); err = -EBUSY; - goto err_free; + goto err_unlock; } perf_install_in_context(ctx, event, cpu); @@ -8577,6 +8590,10 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, return event; +err_unlock: + mutex_unlock(&ctx->mutex); + perf_unpin_context(ctx); + put_ctx(ctx); err_free: free_event(event); err: |