Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756492AbZGGFw4 (ORCPT ); Tue, 7 Jul 2009 01:52:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754591AbZGGFws (ORCPT ); Tue, 7 Jul 2009 01:52:48 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:63564 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753575AbZGGFwr (ORCPT ); Tue, 7 Jul 2009 01:52:47 -0400 Message-ID: <4A52E2B4.6030706@cn.fujitsu.com> Date: Tue, 07 Jul 2009 13:52:52 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Ingo Molnar CC: "K.Prasad" , Alan Stern , Frederic Weisbecker , Steven Rostedt , LKML Subject: [PATCH 2/8] ksym_tracer: Rewrite ksym_trace_filter_read() References: <4A52E291.1020408@cn.fujitsu.com> In-Reply-To: <4A52E291.1020408@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2322 Lines: 74 Reading ksym_trace_filter gave me some arbitrary characters, when it should show nothing. It's because buf is not initialized when there's no filter. Also reduce stack usage by about 512 bytes. Signed-off-by: Li Zefan --- kernel/trace/trace_ksym.c | 29 ++++++++++++++++++----------- 1 files changed, 18 insertions(+), 11 deletions(-) diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c index 085ff05..b6710d3 100644 --- a/kernel/trace/trace_ksym.c +++ b/kernel/trace/trace_ksym.c @@ -35,7 +35,6 @@ #define KSYM_TRACER_MAX HBP_NUM #define KSYM_TRACER_OP_LEN 3 /* rw- */ -#define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1) struct trace_ksym { struct hw_breakpoint *ksym_hbp; @@ -230,25 +229,33 @@ static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf, { struct trace_ksym *entry; struct hlist_node *node; - char buf[KSYM_FILTER_ENTRY_LEN * KSYM_TRACER_MAX]; - ssize_t ret, cnt = 0; + struct trace_seq *s; + ssize_t cnt = 0; + int ret; + + s = kmalloc(sizeof(*s), GFP_KERNEL); + if (!s) + return -ENOMEM; + trace_seq_init(s); mutex_lock(&ksym_tracer_mutex); hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { - cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, "%s:", - entry->ksym_hbp->info.name); + ret = trace_seq_printf(s, "%s:", entry->ksym_hbp->info.name); if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE) - cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, - "-w-\n"); + ret = trace_seq_puts(s, "-w-\n"); else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW) - cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, - "rw-\n"); + ret = trace_seq_puts(s, "rw-\n"); + WARN_ON_ONCE(!ret); } - ret = simple_read_from_buffer(ubuf, count, ppos, buf, strlen(buf)); + + cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len); + mutex_unlock(&ksym_tracer_mutex); - return ret; + kfree(s); + + return cnt; } static ssize_t ksym_trace_filter_write(struct file *file, -- 1.5.4.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/