[PULL 1/3] hw/9pfs: avoid 'path' copy in v9fs_walk()

* [PULL 1/3] hw/9pfs: avoid 'path' copy in v9fs_walk()
  2021-09-02 11:42 [PULL 0/3] 9p queue 2021-09-02 Christian Schoenebeck
  2021-09-02 11:42 ` [PULL 2/3] hw/9pfs: use g_autofree in v9fs_walk() where possible Christian Schoenebeck
  2021-09-02 11:42 ` [PULL 3/3] 9pfs: fix crash in v9fs_walk() Christian Schoenebeck
@ 2021-09-02 11:42 ` Christian Schoenebeck
  2021-09-03 12:08 ` [PULL 0/3] 9p queue 2021-09-02 Peter Maydell
  3 siblings, 0 replies; 5+ messages in thread
From: Christian Schoenebeck @ 2021-09-02 11:42 UTC (permalink / raw)
  To: qemu-devel, Peter Maydell; +Cc: Greg Kurz

The v9fs_walk() function resolves all client submitted path nodes to the
local 'pathes' array. Using a separate string scalar variable 'path'
inside the background worker thread loop and copying that local 'path'
string scalar variable subsequently to the 'pathes' array (at the end of
each loop iteration) is not necessary.

Instead simply resolve each path directly to the 'pathes' array and
don't use the string scalar variable 'path' inside the fs worker thread
loop at all.

The only advantage of the 'path' scalar was that in case of an error
the respective 'pathes' element would not be filled. Right now this is
not an issue as the v9fs_walk() function returns as soon as any error
occurs.

Suggested-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <7dacbecf25b2c9b4a0ce12d689a8a535f09a31e3.1629208359.git.qemu_oss@crudebyte.com>
---
 hw/9pfs/9p.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 2815257f42..4d642ab12a 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1787,7 +1787,8 @@ static void coroutine_fn v9fs_walk(void *opaque)
                 strcmp("..", wnames[name_idx].data))
             {
                 err = s->ops->name_to_path(&s->ctx, &dpath,
-                                        wnames[name_idx].data, &path);
+                                           wnames[name_idx].data,
+                                           &pathes[name_idx]);
                 if (err < 0) {
                     err = -errno;
                     break;
@@ -1796,14 +1797,13 @@ static void coroutine_fn v9fs_walk(void *opaque)
                     err = -EINTR;
                     break;
                 }
-                err = s->ops->lstat(&s->ctx, &path, &stbuf);
+                err = s->ops->lstat(&s->ctx, &pathes[name_idx], &stbuf);
                 if (err < 0) {
                     err = -errno;
                     break;
                 }
                 stbufs[name_idx] = stbuf;
-                v9fs_path_copy(&dpath, &path);
-                v9fs_path_copy(&pathes[name_idx], &path);
+                v9fs_path_copy(&dpath, &pathes[name_idx]);
             }
         }
     });
-- 
2.20.1



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