inherit_event() returns NULL only when it finds orphaned events
otherwise it returns either valid child_event pointer or an error
pointer. Follow the same when it fails to find pmu_ctx.
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221118051539.820-1-ravi.bangoria@amd.com
 
        pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx, child_event);
        if (IS_ERR(pmu_ctx)) {
                free_event(child_event);
-               return NULL;
+               return ERR_CAST(pmu_ctx);
        }
        child_event->pmu_ctx = pmu_ctx;