diff options
author | Gao Xiang <gaoxiang25@huawei.com> | 2018-11-23 01:21:47 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-23 10:53:08 +0100 |
commit | 23edf3abe7abb1d1ab856c893629b96209473a5b (patch) | |
tree | 25d6645efaf8df941d49abeaa72311755b80ca85 | |
parent | 48d4bf3b05a683539a43faa02c6f3091c715c9cc (diff) |
staging: erofs: locked before registering for all new workgroups
Let's make sure that the one registering a workgroup will also
take the primary work lock at first for two reasons:
1) There's no need to introduce such a race window (and consequently
overhead) between registering and locking, other tasks could break
in by chance, and the race seems unnecessary (no benefit at all);
2) It's better to take the primary work when a workgroup
is registered to apply the cache managed policy, for example,
if some other tasks break in, it could turn into the in-place
decompression rather than use as the cached decompression.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/staging/erofs/unzip_vle.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c index 4e5843e8ee35..6aa3c989dd4e 100644 --- a/drivers/staging/erofs/unzip_vle.c +++ b/drivers/staging/erofs/unzip_vle.c @@ -420,18 +420,23 @@ z_erofs_vle_work_register(const struct z_erofs_vle_work_finder *f, work = z_erofs_vle_grab_primary_work(grp); work->pageofs = f->pageofs; + /* + * lock all primary followed works before visible to others + * and mutex_trylock *never* fails for a new workgroup. + */ + mutex_trylock(&work->lock); + 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; } |