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Message-ID: <20230328094605.480557-1-zhengyejian1@huawei.com>
Date: Tue, 28 Mar 2023 17:46:05 +0800
From: Zheng Yejian <zhengyejian1@...wei.com>
To: <axboe@...nel.dk>, <rostedt@...dmis.org>, <mhiramat@...nel.org>
CC: <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-trace-kernel@...r.kernel.org>, <zhengyejian1@...wei.com>
Subject: [PATCH] blktrace: Gracefully return if fail in blk_register_tracepoints()
Currently blk_register_tracepoints() WARN for every registration failure
of block tracepoint, however, blk_trace can still be setup-ed.
It seems better to cleanup registered tracepoints and return error when
a certain registration failed, even if it's a small probability, and
users can know the error and do blk_trace setup again.
Signed-off-by: Zheng Yejian <zhengyejian1@...wei.com>
---
kernel/trace/blktrace.c | 113 +++++++++++++++++++++++++++++++---------
1 file changed, 87 insertions(+), 26 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index d5d94510afd3..62ac72866f02 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -60,7 +60,7 @@ static struct tracer_flags blk_tracer_flags = {
static DEFINE_MUTEX(blk_probe_mutex);
static int blk_probes_ref;
-static void blk_register_tracepoints(void);
+static int blk_register_tracepoints(void);
static void blk_unregister_tracepoints(void);
/*
@@ -330,12 +330,20 @@ static void blk_trace_free(struct request_queue *q, struct blk_trace *bt)
kfree(bt);
}
-static void get_probe_ref(void)
+static int get_probe_ref(void)
{
+ int ret = 0;
+
mutex_lock(&blk_probe_mutex);
- if (++blk_probes_ref == 1)
- blk_register_tracepoints();
+ if (++blk_probes_ref == 1) {
+ ret = blk_register_tracepoints();
+ if (ret) {
+ pr_warn("Could not register block tracepoints\n");
+ --blk_probes_ref;
+ }
+ }
mutex_unlock(&blk_probe_mutex);
+ return ret;
}
static void put_probe_ref(void)
@@ -608,13 +616,14 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
bt->pid = buts->pid;
bt->trace_state = Blktrace_setup;
+ ret = get_probe_ref();
+ if (ret)
+ goto err;
rcu_assign_pointer(q->blk_trace, bt);
- get_probe_ref();
+ return 0;
- ret = 0;
err:
- if (ret)
- blk_trace_free(q, bt);
+ blk_trace_free(q, bt);
return ret;
}
@@ -1088,42 +1097,92 @@ void blk_add_driver_data(struct request *rq, void *data, size_t len)
}
EXPORT_SYMBOL_GPL(blk_add_driver_data);
-static void blk_register_tracepoints(void)
+static int blk_register_tracepoints(void)
{
int ret;
ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
- WARN_ON(ret);
+ if (ret)
+ return ret;
ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_rq_issue;
ret = register_trace_block_rq_merge(blk_add_trace_rq_merge, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_rq_merge;
ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_rq_requeue;
ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_rq_complete;
ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_bio_bounce;
ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_bio_complete;
ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_bio_backmerge;
ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_bio_frontmerge;
ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_bio_queue;
ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_getrq;
ret = register_trace_block_plug(blk_add_trace_plug, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_plug;
ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_unplug;
ret = register_trace_block_split(blk_add_trace_split, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_split;
ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_bio_remap;
ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
- WARN_ON(ret);
+ if (ret)
+ goto err_block_rq_remap;
+ return 0;
+
+err_block_rq_remap:
+ unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
+err_block_bio_remap:
+ unregister_trace_block_split(blk_add_trace_split, NULL);
+err_block_split:
+ unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
+err_block_unplug:
+ unregister_trace_block_plug(blk_add_trace_plug, NULL);
+err_block_plug:
+ unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
+err_block_getrq:
+ unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
+err_block_bio_queue:
+ unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
+err_block_bio_frontmerge:
+ unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
+err_block_bio_backmerge:
+ unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
+err_block_bio_complete:
+ unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
+err_block_bio_bounce:
+ unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
+err_block_rq_complete:
+ unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
+err_block_rq_requeue:
+ unregister_trace_block_rq_merge(blk_add_trace_rq_merge, NULL);
+err_block_rq_merge:
+ unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
+err_block_rq_issue:
+ unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
+ tracepoint_synchronize_unregister();
+ return ret;
}
static void blk_unregister_tracepoints(void)
@@ -1643,8 +1702,10 @@ static int blk_trace_setup_queue(struct request_queue *q,
blk_trace_setup_lba(bt, bdev);
+ ret = get_probe_ref();
+ if (ret)
+ goto free_bt;
rcu_assign_pointer(q->blk_trace, bt);
- get_probe_ref();
return 0;
free_bt:
--
2.25.1
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