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DateFri, 20 Mar 2009 10:03:09 -0300
FromArnaldo Carvalho de Melo <>
SubjectRe: [PATCH 3/7] blktrace: remove blk_probe_mutex
Em Fri, Mar 20, 2009 at 09:48:26AM +0800, Li Zefan escreveu:
> blk_register_tracepoints() always returns 0, so make it return void, thus
> we don't need to use blk_probe_mutex to protect blk_probes_ref.
>
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

Historic reasons, when I first worked on this I found all those WARN_ONs
in blk_register_tracepoints a bogosity that should be later fixed, but
to reduce the patch size I never got around to submit the proper patch,
so I don't think that the fix is what you suggests, here it is what I
had before I removed the non-essential parts of the patch:

+static void blk_tracer_error(const char *name)
+{
+ pr_info("blk trace: Couldn't activate tracepoint "
+ "probe to block_%s\n", name);
+}
+
+#define register_trace_block(tpoint) \
+ ret = register_trace_block_##tpoint(blk_add_trace_##tpoint); \
+ if (ret) { \
+ blk_tracer_error(#tpoint); \
+ goto *exit_point; \
+ } else \
+ exit_point = &&fail_deprobe_##tpoint;
+
+
+#define fail_trace_block(tpoint) \
+ fail_deprobe_##tpoint: \
+ unregister_trace_block_##tpoint(blk_add_trace_##tpoint)
+
+static int tracing_blk_register(void)
+{
+ int ret;
+ void *exit_point = &&error;
+
+ register_trace_block(rq_abort);
+ register_trace_block(rq_insert);
+ register_trace_block(rq_issue);
+ register_trace_block(rq_requeue);
+ register_trace_block(rq_complete);
+ register_trace_block(bio_bounce);
+ register_trace_block(bio_backmerge);
+ register_trace_block(bio_frontmerge);
+ register_trace_block(bio_queue);
+ register_trace_block(getrq);
+ register_trace_block(sleeprq);
+ register_trace_block(plug);
+ register_trace_block(unplug_timer);
+ register_trace_block(unplug_io);
+ register_trace_block(split);
+ register_trace_block(remap);
+
+ return 0;
+
+ fail_trace_block(remap);
+ fail_trace_block(split);
+ fail_trace_block(unplug_io);
+ fail_trace_block(unplug_timer);
+ fail_trace_block(plug);
+ fail_trace_block(sleeprq);
+ fail_trace_block(getrq);
+ fail_trace_block(bio_queue);
+ fail_trace_block(bio_frontmerge);
+ fail_trace_block(bio_backmerge);
+ fail_trace_block(bio_bounce);
+ fail_trace_block(rq_complete);
+ fail_trace_block(rq_requeue);
+ fail_trace_block(rq_issue);
+ fail_trace_block(rq_insert);
+ fail_trace_block(rq_abort);
+error:
+ return ret;
+}
+
+static void tracing_blk_unregister(void)
+{
+ unregister_trace_block_remap(blk_add_trace_remap);
+ unregister_trace_block_split(blk_add_trace_split);
+ unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
+ unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
+ unregister_trace_block_plug(blk_add_trace_plug);
+ unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
+ unregister_trace_block_getrq(blk_add_trace_getrq);
+ unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
+ unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
+ unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
+ unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
+ unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
+ unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
+ unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
+ unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
+ unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
+ unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
+ tracepoint_synchronize_unregister();
+}
Regards,

- Arnaldo


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