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SubjectRe: [tip:tracing/urgent] tracing: Allocate the ftrace event profile buffer dynamically
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On Sat, 2009-09-19 at 07:58 +0000, tip-bot for Frederic Weisbecker
wrote:

> +/*
> + * We can't use a size but a type in alloc_percpu()
> + * So let's create a dummy type that matches the desired size
> + */
> +typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
> +
> static int ftrace_profile_enable_event(struct ftrace_event_call *event)
> {
> + char *buf;
> + int ret;
> +
> if (atomic_inc_return(&event->profile_count))
> return 0;
>
> - return event->profile_enable();
> + buf = (char *)alloc_percpu(profile_buf_t);
> + if (!buf)
> + return -ENOMEM;

Ingo,

Did you pull in the version that allocates a buffer for each event? I
thought Frederic made just a global per cpu buffer that all events can
use. The buffer is just a temporary storage that will be too big to put
on the stack.

-- Steve

> +
> + rcu_assign_pointer(event->profile_buf, buf);
> +
> + buf = (char *)alloc_percpu(profile_buf_t);
> + if (!buf) {
> + ret = -ENOMEM;
> + goto fail_nmi;
> + }
> +
> + rcu_assign_pointer(event->profile_buf_nmi, buf);
> +
> + ret = event->profile_enable();
> + if (!ret)
> + return 0;
> +
> + kfree(event->profile_buf_nmi);
> +fail_nmi:
> + kfree(event->profile_buf);
> +
> + return ret;
> }
>



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