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SubjectRe: ftrace does not work on cpus > 999.
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On Sat, 2010-10-16 at 16:45 +0200, Frederic Weisbecker wrote:

> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 9ec59f5..3565f9e 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3999,7 +3999,7 @@ static void tracing_init_debugfs_percpu(long cpu)
> /* strlen(cpu) + MAX(log10(cpu)) + '\0' */
> char cpu_dir[7];
>
> - if (cpu > 999 || cpu < 0)
> + if (cpu < 0)
> return;
>
> sprintf(cpu_dir, "cpu%ld", cpu);

You need to change the size of cpu_dir, otherwise this will overflow.

The other case is to dynamically allocate cpu_dir.

char *cpu_dir;
int count = cpu;
int size;

if (cpu < 0)
return;

/* log10 sizeof cpu */
for (size = 0; count > 0; count /= 10, size++)
;

cpu_dir = kmalloc(size + 4, GFP_KERNEL);

if (!cpu_dir)
return;

snprintf(cpu_dir, size + 4, "cpu%ld", cpu);

[...]

kfree(cpu_dir);

-- Steve




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