tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare()

Every perf_trace_buf_prepare() caller does
WARN_ONCE(size > PERF_MAX_TRACE_SIZE, message) and "message" is
almost the same.

Shift this WARN_ONCE() into perf_trace_buf_prepare(). This changes
the meaning of _ONCE, but I think this is fine.

	- 4947014 2932448 10104832  17984294  1126b26 vmlinux
	+ 4948422 2932448 10104832  17985702  11270a6 vmlinux

on my build.

Link: http://lkml.kernel.org/r/20130617170211.GA19813@redhat.com

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

5 files changed, 4 insertions, 24 deletions

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index d615f78cc6b6..41a6643e2136 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -670,10 +670,6 @@ perf_trace_##call(void *__data, proto)					\
                              sizeof(u64));                              \
         __entry_size -= sizeof(u32);                                    \
                                                                         \
-        if (WARN_ONCE(__entry_size > PERF_MAX_TRACE_SIZE,               \
-                      "profile buffer not large enough"))               \
-                return;                                                 \
-                                                                        \
         entry = (struct ftrace_raw_##call *)perf_trace_buf_prepare(     \
                 __entry_size, event_call->event.type, &__regs, &rctx);  \
         if (!entry)                                                     \
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 12df5573086e..80c36bcf66e8 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -236,6 +236,10 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
 
         BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
 
+        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+                        "perf buffer not large enough"))
+                return NULL;
+
         pc = preempt_count();
 
         *rctxp = perf_swevent_get_recursion_context();
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7ed6976493c8..ae6ce835b023 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1087,9 +1087,6 @@ kprobe_perf_func(struct trace_probe *tp, struct pt_regs *regs)
         __size = sizeof(*entry) + tp->size + dsize;
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                     "profile buffer not large enough"))
-                return;
 
         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
         if (!entry)
@@ -1120,9 +1117,6 @@ kretprobe_perf_func(struct trace_probe *tp, struct kretprobe_instance *ri,
         __size = sizeof(*entry) + tp->size + dsize;
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                     "profile buffer not large enough"))
-                return;
 
         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
         if (!entry)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index ac0085777fbd..8fd03657bc7d 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -575,10 +575,6 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
         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)
@@ -652,14 +648,6 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
         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)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index d5d0cd368a56..a23d2d71188e 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -818,8 +818,6 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
 
         size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
         size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
-                return;
 
         preempt_disable();
         head = this_cpu_ptr(call->perf_events);