[PATCH-for-5.2 v2 1/2] block/block-backend: Trace blk_attach_dev()

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

Add a trace event to follow devices attaching block drives:

  $ qemu-system-arm -M n800 -trace blk_\*
  9513@1594040428.738162:blk_attach_dev attaching blk 'sd0' to device 'omap2-mmc'
  9513@1594040428.738189:blk_attach_dev attaching blk 'sd0' to device 'sd-card'
  qemu-system-arm: sd_init failed: blk 'sd0' already attached by device 'sd-card'

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 block/block-backend.c | 1 +
 block/trace-events    | 1 +
 2 files changed, 2 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 0bf0188133..63ff940ef9 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -888,6 +888,7 @@ void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm)
  */
 int blk_attach_dev(BlockBackend *blk, DeviceState *dev)
 {
+    trace_blk_attach_dev(blk_name(blk), object_get_typename(OBJECT(dev)));
     if (blk->dev) {
         return -EBUSY;
     }
diff --git a/block/trace-events b/block/trace-events
index dbe76a7613..aa641c2034 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -9,6 +9,7 @@ blk_co_preadv(void *blk, void *bs, int64_t offset, unsigned int bytes, int flags
 blk_co_pwritev(void *blk, void *bs, int64_t offset, unsigned int bytes, int flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x"
 blk_root_attach(void *child, void *blk, void *bs) "child %p blk %p bs %p"
 blk_root_detach(void *child, void *blk, void *bs) "child %p blk %p bs %p"
+blk_attach_dev(const char *blk_name, const char *dev_name) "attaching blk '%s' to device '%s'"
 
 # io.c
 bdrv_co_preadv(void *bs, int64_t offset, int64_t nbytes, unsigned int flags) "bs %p offset %"PRId64" nbytes %"PRId64" flags 0x%x"
-- 
2.21.3