Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753184AbaBMB3h (ORCPT ); Wed, 12 Feb 2014 20:29:37 -0500 Received: from mail9.hitachi.co.jp ([133.145.228.44]:45577 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752394AbaBMB26 (ORCPT ); Wed, 12 Feb 2014 20:28:58 -0500 X-AuditID: 85900ec0-cff26b9000001514-0a-52fc1fd81d19 Subject: [PATCH -tip RESEND 1/2] ftrace: Make saved_cmdlines use seq_read To: linux-kernel@vger.kernel.org, Steven Rostedt From: Yoshihiro YUNOMAE Cc: Hidehiro Kawai , Frederic Weisbecker , Masami Hiramatsu , Ingo Molnar , yrl.pp-manager.tt@hitachi.com Date: Thu, 13 Feb 2014 10:28:55 +0900 Message-ID: <20140213012855.15283.94188.stgit@yunodevel> In-Reply-To: <20140213012852.15283.50473.stgit@yunodevel> References: <20140213012852.15283.50473.stgit@yunodevel> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Current tracing_saved_cmdlines_read() implementation is naive; simply allocate a big buffer, construct output data on the buffer for each read operation, and then copy a portion of the buffer to the user space buffer. This can cause a couple of issues such as a slow memory allocation, high cpu usage, and a corruption of the output data. To address these issues, make saved_cmdlines use seq_read. Signed-off-by: Hidehiro Kawai Signed-off-by: Yoshihiro YUNOMAE Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: linux-kernel@vger.kernel.org --- kernel/trace/trace.c | 89 ++++++++++++++++++++++++++++++-------------------- 1 file changed, 54 insertions(+), 35 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6a9212d..f930f4d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3676,55 +3676,74 @@ static const struct file_operations tracing_readme_fops = { .llseek = generic_file_llseek, }; -static ssize_t -tracing_saved_cmdlines_read(struct file *file, char __user *ubuf, - size_t cnt, loff_t *ppos) +static void *saved_cmdlines_next(struct seq_file *m, void *v, loff_t *pos) { - char *buf_comm; - char *file_buf; - char *buf; - int len = 0; - int pid; - int i; + unsigned int *ptr = v; - file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL); - if (!file_buf) - return -ENOMEM; + if (*pos || m->count) + ptr++; - buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL); - if (!buf_comm) { - kfree(file_buf); - return -ENOMEM; - } + (*pos)++; + + for (; ptr < &map_cmdline_to_pid[SAVED_CMDLINES]; ptr++) { + if (*ptr == -1 || *ptr == NO_CMDLINE_MAP) + continue; - buf = file_buf; + return ptr; + } - for (i = 0; i < SAVED_CMDLINES; i++) { - int r; + return NULL; +} - pid = map_cmdline_to_pid[i]; - if (pid == -1 || pid == NO_CMDLINE_MAP) - continue; +static void *saved_cmdlines_start(struct seq_file *m, loff_t *pos) +{ + void *v; + loff_t l = 0; - trace_find_cmdline(pid, buf_comm); - r = sprintf(buf, "%d %s\n", pid, buf_comm); - buf += r; - len += r; + v = &map_cmdline_to_pid[0]; + while (l <= *pos) { + v = saved_cmdlines_next(m, v, &l); + if (!v) + return NULL; } - len = simple_read_from_buffer(ubuf, cnt, ppos, - file_buf, len); + return v; +} - kfree(file_buf); - kfree(buf_comm); +static void saved_cmdlines_stop(struct seq_file *m, void *v) +{ +} - return len; +static int saved_cmdlines_show(struct seq_file *m, void *v) +{ + char buf[TASK_COMM_LEN]; + unsigned int *pid = v; + + trace_find_cmdline(*pid, buf); + seq_printf(m, "%d %s\n", *pid, buf); + return 0; +} + +static const struct seq_operations tracing_saved_cmdlines_seq_ops = { + .start = saved_cmdlines_start, + .next = saved_cmdlines_next, + .stop = saved_cmdlines_stop, + .show = saved_cmdlines_show, +}; + +static int tracing_saved_cmdlines_open(struct inode *inode, struct file *filp) +{ + if (tracing_disabled) + return -ENODEV; + + return seq_open(filp, &tracing_saved_cmdlines_seq_ops); } static const struct file_operations tracing_saved_cmdlines_fops = { - .open = tracing_open_generic, - .read = tracing_saved_cmdlines_read, - .llseek = generic_file_llseek, + .open = tracing_saved_cmdlines_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, }; static ssize_t -- 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/