block: make blktrace use per-cpu buffers for message notes

[firefly-linux-kernel-4.4.55.git] / block / blktrace.c

diff --git a/block/blktrace.c b/block/blktrace.c
index 20e11f354f117d83e4c83356a99b09c70a87939e..7ae87cc4a163fc0dfcae0f65e6d25e9b185c4b91 100644 (file)
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -79,13 +79,16 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 {
        int n;
        va_list args;
-       static char bt_msg_buf[BLK_TN_MAX_MSG];
+       char *buf;
 
+       preempt_disable();
+       buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
        va_start(args, fmt);
-       n = vscnprintf(bt_msg_buf, BLK_TN_MAX_MSG, fmt, args);
+       n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
        va_end(args);
 
-       trace_note(bt, 0, BLK_TN_MESSAGE, bt_msg_buf, n);
+       trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
+       preempt_enable();
 }
 EXPORT_SYMBOL_GPL(__trace_note_message);
 
@@ -246,6 +249,7 @@ static void blk_trace_cleanup(struct blk_trace *bt)
        debugfs_remove(bt->dropped_file);
        blk_remove_tree(bt->dir);
        free_percpu(bt->sequence);
+       free_percpu(bt->msg_data);
        kfree(bt);
 }
 
@@ -360,6 +364,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
        if (!bt->sequence)
                goto err;
 
+       bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG);
+       if (!bt->msg_data)
+               goto err;
+
        ret = -ENOENT;
        dir = blk_create_tree(buts->name);
        if (!dir)
@@ -406,6 +414,7 @@ err:
                if (bt->dropped_file)
                        debugfs_remove(bt->dropped_file);
                free_percpu(bt->sequence);
+               free_percpu(bt->msg_data);
                if (bt->rchan)
                        relay_close(bt->rchan);
                kfree(bt);