lkml.org 
[lkml]   [2015]   [Apr]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 03/19] tools lib traceevent: Honor operator priority
Date
From: Namhyung Kim <namhyung@kernel.org>

Currently it ignores operator priority and just sets processed args as a
right operand. But it could result in priority inversion in case that
the right operand is also a operator arg and its priority is lower.

For example, following print format is from new kmem events.

"page=%p", REC->pfn != -1UL ? (((struct page *)(0xffffea0000000000UL)) + (REC->pfn)) : ((void *)0)

But this was treated as below:

REC->pfn != ((null - 1UL) ? ((struct page *)0xffffea0000000000UL + REC->pfn) : (void *) 0)

In this case, the right arg was '?' operator which has lower priority.
But it just sets the whole arg so making the output confusing - page was
always 0 or 1 since that's the result of logical operation.

With this patch, it can handle it properly like following:

((REC->pfn != (null - 1UL)) ? ((struct page *)0xffffea0000000000UL + REC->pfn) : (void *) 0)

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1428298576-9785-10-git-send-email-namhyung@kernel.org
[ Replaced 'swap' with 'rotate' in a comment as requested by Steve and agreed by Namhyung ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/traceevent/event-parse.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 6d31b6419d37..12a7e2a40c89 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -1939,7 +1939,22 @@ process_op(struct event_format *event, struct print_arg *arg, char **tok)
goto out_warn_free;

type = process_arg_token(event, right, tok, type);
- arg->op.right = right;
+
+ if (right->type == PRINT_OP &&
+ get_op_prio(arg->op.op) < get_op_prio(right->op.op)) {
+ struct print_arg tmp;
+
+ /* rotate ops according to the priority */
+ arg->op.right = right->op.left;
+
+ tmp = *arg;
+ *arg = *right;
+ *right = tmp;
+
+ arg->op.left = right;
+ } else {
+ arg->op.right = right;
+ }

} else if (strcmp(token, "[") == 0) {

--
1.9.3


\
 
 \ /
  Last update: 2015-04-08 17:01    [W:0.150 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site