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Commit 69abe6a5 authored by Avadh Patel's avatar Avadh Patel Committed by Ingo Molnar
Browse files

tracing: add saved_cmdlines file to show cached task comms 



Export the cached task comms to userspace. This allows user apps to translate
the pids from a trace into their respective task command lines.

[ Impact: let userspace apps reading binary buffer know comm's of pids ]

Signed-off-by: default avatarAvadh Patel <avadh4all@gmail.com>
[ added error checking and use of buf pointer to index file_buf ]
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent d1b182a8

kernel/trace/trace.c

+53 −0
Original line number Diff line number Diff line
@@ -2421,6 +2421,56 @@ static const struct file_operations tracing_readme_fops = { 
	.read		= tracing_readme_read,

};



static ssize_t

tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,

				size_t cnt, loff_t *ppos)

{

	char *buf_comm;

	char *file_buf;

	char *buf;

	int len = 0;

	int pid;

	int i;



	file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);

	if (!file_buf)

		return -ENOMEM;



	buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);

	if (!buf_comm) {

		kfree(file_buf);

		return -ENOMEM;

	}



	buf = file_buf;



	for (i = 0; i < SAVED_CMDLINES; i++) {

		int r;



		pid = map_cmdline_to_pid[i];

		if (pid == -1 || pid == NO_CMDLINE_MAP)

			continue;



		trace_find_cmdline(pid, buf_comm);

		r = sprintf(buf, "%d %s\n", pid, buf_comm);

		buf += r;

		len += r;

	}



	len = simple_read_from_buffer(ubuf, cnt, ppos,

				      file_buf, len);



	kfree(file_buf);

	kfree(buf_comm);



	return len;

}



static const struct file_operations tracing_saved_cmdlines_fops = {

    .open       = tracing_open_generic,

    .read       = tracing_saved_cmdlines_read,

};



static ssize_t

tracing_ctrl_read(struct file *filp, char __user *ubuf,

		  size_t cnt, loff_t *ppos)
@@ -3973,6 +4023,9 @@ static __init int tracer_init_debugfs(void) 
	trace_create_file("trace_marker", 0220, d_tracer,

			NULL, &tracing_mark_fops);



	trace_create_file("saved_cmdlines", 0444, d_tracer,

			NULL, &tracing_saved_cmdlines_fops);



#ifdef CONFIG_DYNAMIC_FTRACE

	trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,

			&ftrace_update_tot_cnt, &tracing_dyn_info_fops);