Re: [PATCH 2/2] trace-cmd: Reset CPU mask to its default value with "trace-cmd reset".

[Steven Rostedt <rostedt@goodmis.org>]

[ Added back the list, as this is good to document ]

On Tue, 1 Oct 2019 14:17:08 +0200
Eugene Syromyatnikov <evgsyr@gmail.com> wrote:

> On Mon, Sep 30, 2019 at 11:13 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> >         if (bits)
> >                 sprintf(buf, "%x", (1 << bits) - 1);
> >         while (fullwords-- > 0)
> >                 strcat(buf, "ffffffff");  
> Additional commas that split 32-bit chunks are needed here, if I read
> lib/bitmap.c:__bitmap_parse correctly.
> 

You're right. I just tested it:

 # echo fffffffff > /debug/tracing/tracing_cpumask 
-bash: echo: write error: Value too large for defined data type
 # echo f,ffffffff > /debug/tracing/tracing_cpumask 
 # 


This should work then:

	int fullwords;
	char *buf;
	int bits;
	int cpus;
	int len;

	fullwords = (cpus - 1) / 32;
	bits = (cpus - 1) % 32 + 1;
	len = (fullwords + 1) * 9;

	buf = malloc(len + 1);
	buf[0] = '\0';

	if (bits)
		sprintf(buf, "%x", (unsigned int)((1ULL << bits) - 1));
	while (fullwords-- > 0)
		strcat(buf, ",ffffffff");

-- Steve