On 03/14, Peter Zijlstra wrote: > > On Tue, Mar 07, 2017 at 05:51:32PM +0100, Oleg Nesterov wrote: > > > inherit_event() returns NULL under is_orphaned_event() check, not ERR_PTR(). > > Is it correct? > > Yes. This is all a tad tricky, but it seems to be correct. > > By returning NULL, not an error, we affect the silent discard of > orphaned events. This is correct, because otherwise > perf_event_release_kernel() would have come by and explicitly discarded > those events for us anyway.
Thanks... I'll try to understand this later. > @@ -10608,7 +10627,6 @@ inherit_task_group(struct perf_event *event, struct > task_struct *parent, > * First allocate and initialize a context for the > * child. > */ > - > child_ctx = alloc_perf_context(parent_ctx->pmu, child); > if (!child_ctx) > return -ENOMEM; > @@ -10670,7 +10688,7 @@ static int perf_event_init_context(struct task_struct > *child, int ctxn) > ret = inherit_task_group(event, parent, parent_ctx, > child, ctxn, &inherited_all); > if (ret) > - break; > + goto out_unlock; > } > > /* > @@ -10686,7 +10704,7 @@ static int perf_event_init_context(struct task_struct > *child, int ctxn) > ret = inherit_task_group(event, parent, parent_ctx, > child, ctxn, &inherited_all); > if (ret) > - break; > + goto out_unlock; With this change you can also simplify inherit_task_group() a little bit, it no longer needs to nullify *inherited_all if inherit_group() fails. Oleg.
