1 files changed, 9 insertions, 17 deletions

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 322e16461072..8fd03657bc7d 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -175,7 +175,7 @@ print_syscall_exit(struct trace_iterator *iter, int flags,
         entry = syscall_nr_to_meta(syscall);
 
         if (!entry) {
-                trace_seq_printf(s, "\n");
+                trace_seq_putc(s, '\n');
                 return TRACE_TYPE_HANDLED;
         }
 
@@ -566,15 +566,15 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
         if (!sys_data)
                 return;
 
+        head = this_cpu_ptr(sys_data->enter_event->perf_events);
+        if (hlist_empty(head))
+                return;
+
         /* get the size after alignment with the u32 buffer size field */
         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
         size = ALIGN(size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
 
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                      "perf buffer not large enough"))
-                return;
-
         rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
                                 sys_data->enter_event->event.type, regs, &rctx);
         if (!rec)
@@ -583,8 +583,6 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
         rec->nr = syscall_nr;
         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
                                (unsigned long *)&rec->args);
-
-        head = this_cpu_ptr(sys_data->enter_event->perf_events);
         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
@@ -642,18 +640,14 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
         if (!sys_data)
                 return;
 
+        head = this_cpu_ptr(sys_data->exit_event->perf_events);
+        if (hlist_empty(head))
+                return;
+
         /* We can probably do that at build time */
         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
 
-        /*
-         * Impossible, but be paranoid with the future
-         * How to put this check outside runtime?
-         */
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                "exit event has grown above perf buffer size"))
-                return;
-
         rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
                                 sys_data->exit_event->event.type, regs, &rctx);
         if (!rec)
@@ -661,8 +655,6 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 
         rec->nr = syscall_nr;
         rec->ret = syscall_get_return_value(current, regs);
-
-        head = this_cpu_ptr(sys_data->exit_event->perf_events);
         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }