2 files changed, 14 insertions, 4 deletions

diff --git a/block/blktrace.c b/block/blktrace.c
index 20e11f354f11..7ae87cc4a163 100644
--- 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);
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index b7cd8f1eedbe..e3ef903aae88 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -121,6 +121,7 @@ struct blk_trace {
         int trace_state;
         struct rchan *rchan;
         unsigned long *sequence;
+        unsigned char *msg_data;
         u16 act_mask;
         u64 start_lba;
         u64 end_lba;
@@ -172,7 +173,7 @@ extern void __trace_note_message(struct blk_trace *, const char *fmt, ...);
                 if (unlikely(bt))                                       \
                         __trace_note_message(bt, fmt, ##__VA_ARGS__);   \
         } while (0)
-#define BLK_TN_MAX_MSG          1024
+#define BLK_TN_MAX_MSG          128
 
 /**
  * blk_add_trace_rq - Add a trace for a request oriented action