diff options
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/core.c | 34 | ||||
| -rw-r--r-- | kernel/events/uprobes.c | 6 |
2 files changed, 34 insertions, 6 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 47996766e3da..1cf24b3e42ec 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2320,7 +2320,7 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, next_parent = rcu_dereference(next_ctx->parent_ctx); /* If neither context have a parent context; they cannot be clones. */ - if (!parent && !next_parent) + if (!parent || !next_parent) goto unlock; if (next_parent == ctx || next_ctx == parent || next_parent == parent) { @@ -7464,7 +7464,19 @@ __perf_event_exit_task(struct perf_event *child_event, struct perf_event_context *child_ctx, struct task_struct *child) { - perf_remove_from_context(child_event, true); + /* + * Do not destroy the 'original' grouping; because of the context + * switch optimization the original events could've ended up in a + * random child task. + * + * If we were to destroy the original group, all group related + * operations would cease to function properly after this random + * child dies. + * + * Do destroy all inherited groups, we don't care about those + * and being thorough is better. + */ + perf_remove_from_context(child_event, !!child_event->parent); /* * It can happen that the parent exits first, and has events @@ -7480,7 +7492,7 @@ __perf_event_exit_task(struct perf_event *child_event, static void perf_event_exit_task_context(struct task_struct *child, int ctxn) { struct perf_event *child_event, *next; - struct perf_event_context *child_ctx; + struct perf_event_context *child_ctx, *parent_ctx; unsigned long flags; if (likely(!child->perf_event_ctxp[ctxn])) { @@ -7505,6 +7517,15 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn) raw_spin_lock(&child_ctx->lock); task_ctx_sched_out(child_ctx); child->perf_event_ctxp[ctxn] = NULL; + + /* + * In order to avoid freeing: child_ctx->parent_ctx->task + * under perf_event_context::lock, grab another reference. + */ + parent_ctx = child_ctx->parent_ctx; + if (parent_ctx) + get_ctx(parent_ctx); + /* * If this context is a clone; unclone it so it can't get * swapped to another process while we're removing all @@ -7515,6 +7536,13 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn) raw_spin_unlock_irqrestore(&child_ctx->lock, flags); /* + * Now that we no longer hold perf_event_context::lock, drop + * our extra child_ctx->parent_ctx reference. + */ + if (parent_ctx) + put_ctx(parent_ctx); + + /* * Report the task dead after unscheduling the events so that we * won't get any samples after PERF_RECORD_EXIT. We can however still * get a few PERF_RECORD_READ events. diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index c445e392e93f..6f3254e8c137 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -846,7 +846,7 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u { int err; - if (!consumer_del(uprobe, uc)) /* WARN? */ + if (WARN_ON(!consumer_del(uprobe, uc))) return; err = register_for_each_vma(uprobe, NULL); @@ -927,7 +927,7 @@ int uprobe_apply(struct inode *inode, loff_t offset, int ret = -ENOENT; uprobe = find_uprobe(inode, offset); - if (!uprobe) + if (WARN_ON(!uprobe)) return ret; down_write(&uprobe->register_rwsem); @@ -952,7 +952,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume struct uprobe *uprobe; uprobe = find_uprobe(inode, offset); - if (!uprobe) + if (WARN_ON(!uprobe)) return; down_write(&uprobe->register_rwsem); |