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SubjectRe: [PATCH 4/6] uprobes/tracing: Introduce is_trace_uprobe_enabled()
* Oleg Nesterov <oleg@redhat.com> [2013-01-31 20:18:25]:

> probe_event_enable/disable() check tu->consumer != NULL to avoid the
> wrong uprobe_register/unregister().
>
> We are going to kill this pointer and "struct uprobe_trace_consumer",
> so we add the new helper, is_trace_uprobe_enabled(), which can rely
> on TP_FLAG_TRACE/TP_FLAG_PROFILE instead.
>
> Note: the current logic doesn't look optimal, it is not clear why
> TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive, we will probably
> change this later.
>
> Also kill the unused TP_FLAG_UPROBE.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>


Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> ---
> kernel/trace/trace_probe.h | 1 -
> kernel/trace/trace_uprobe.c | 9 +++++++--
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 9337086..5c7e09d 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -66,7 +66,6 @@
> #define TP_FLAG_TRACE 1
> #define TP_FLAG_PROFILE 2
> #define TP_FLAG_REGISTERED 4
> -#define TP_FLAG_UPROBE 8
>
>
> /* data_rloc: data relative location, compatible with u32 */
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index f02bbec..947379a 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -536,12 +536,17 @@ partial:
> return TRACE_TYPE_PARTIAL_LINE;
> }
>
> +static inline bool is_trace_uprobe_enabled(struct trace_uprobe *tu)
> +{
> + return tu->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE);
> +}
> +
> static int probe_event_enable(struct trace_uprobe *tu, int flag)
> {
> struct uprobe_trace_consumer *utc;
> int ret = 0;
>
> - if (tu->consumer)
> + if (is_trace_uprobe_enabled(tu))
> return -EINTR;
>
> utc = kzalloc(sizeof(struct uprobe_trace_consumer), GFP_KERNEL);
> @@ -565,7 +570,7 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag)
>
> static void probe_event_disable(struct trace_uprobe *tu, int flag)
> {
> - if (!tu->consumer)
> + if (!is_trace_uprobe_enabled(tu))
> return;
>
> uprobe_unregister(tu->inode, tu->offset, &tu->consumer->cons);
> --
> 1.5.5.1
>

--
Thanks and Regards
Srikar Dronamraju



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