Merge tag 'gpio-v4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux...

[cascardo/linux.git] / kernel / events / callchain.c

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 179ef46..e9fdb52 100644 (file)
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -104,7 +104,7 @@ fail:
        return -ENOMEM;
 }
 
-int get_callchain_buffers(void)
+int get_callchain_buffers(int event_max_stack)
 {
        int err = 0;
        int count;
@@ -121,6 +121,15 @@ int get_callchain_buffers(void)
                /* If the allocation failed, give up */
                if (!callchain_cpus_entries)
                        err = -ENOMEM;
+               /*
+                * If requesting per event more than the global cap,
+                * return a different error to help userspace figure
+                * this out.
+                *
+                * And also do it here so that we have &callchain_mutex held.
+                */
+               if (event_max_stack > sysctl_perf_event_max_stack)
+                       err = -EOVERFLOW;
                goto exit;
        }
 
@@ -174,11 +183,12 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
        bool user   = !event->attr.exclude_callchain_user;
        /* Disallow cross-task user callchains. */
        bool crosstask = event->ctx->task && event->ctx->task != current;
+       const u32 max_stack = event->attr.sample_max_stack;
 
        if (!kernel && !user)
                return NULL;
 
-       return get_perf_callchain(regs, 0, kernel, user, sysctl_perf_event_max_stack, crosstask, true);
+       return get_perf_callchain(regs, 0, kernel, user, max_stack, crosstask, true);
 }
 
 struct perf_callchain_entry *