block: make blktrace use per-cpu buffers for message notes
Currently it uses a single static char array, but that risks
being corrupted when multiple users issue message notes at the
same time. Make the buffers dynamically allocated when the trace
is setup and make them per-cpu instead.
The default max message size of 1k is also very large, the
interface is mainly for small text notes. So shrink it to 128 bytes.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index b7cd8f1..e3ef903 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -121,6 +121,7 @@
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 @@
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