[WIP] [PREVIEW] [RFC PATCH 1/3] staging: erofs: serialize access to works strictly

[Gao Xiang]

Make sure other accesses to primary works are serialized
after the primary followed work ends.

Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
Hi,

This patch series are testing under pressure now, and could be changed later.

Thanks,
Gao Xiang

 drivers/staging/erofs/unzip_vle.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index 6c5739a..eae9be1 100644
--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -395,18 +395,21 @@ struct z_erofs_vle_work_finder {
 
 	mutex_init(&work->lock);
 
+	/* lock all primary followed works before visible to others */
+	if (unlikely(!mutex_trylock(&work->lock)))
+		BUG();
+
 	if (gnew) {
 		int err = erofs_register_workgroup(f->sb, &grp->obj, 0);
 
 		if (err) {
+			mutex_unlock(&work->lock);
 			kmem_cache_free(z_erofs_workgroup_cachep, grp);
 			return ERR_PTR(-EAGAIN);
 		}
 	}
 
 	*f->owned_head = *f->grp_ret = grp;
-
-	mutex_lock(&work->lock);
 	return work;
 }
 
-- 
1.9.1