lkml.org 
[lkml]   [2019]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH next 1/3] debugfs: Provide debugfs_[set|clear|test]_lowest_bit()
Date
Provide debugfs_[set|clear|test]_lowest_bit() helper, which
could test, set and clear the lowest bit of a pointer, and
will be used in the subsequent patches.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
fs/debugfs/file.c | 7 +++----
fs/debugfs/inode.c | 7 +++----
fs/debugfs/internal.h | 5 ++++-
3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index dede25247b81..38c17a99eb17 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -50,7 +50,7 @@ const struct file_operations *debugfs_real_fops(const struct file *filp)
{
struct debugfs_fsdata *fsd = F_DENTRY(filp)->d_fsdata;

- if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) {
+ if (debugfs_test_lowest_bit(fsd)) {
/*
* Urgh, we've been called w/o a protecting
* debugfs_file_get().
@@ -84,15 +84,14 @@ int debugfs_file_get(struct dentry *dentry)
void *d_fsd;

d_fsd = READ_ONCE(dentry->d_fsdata);
- if (!((unsigned long)d_fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)) {
+ if (!debugfs_test_lowest_bit(d_fsd)) {
fsd = d_fsd;
} else {
fsd = kmalloc(sizeof(*fsd), GFP_KERNEL);
if (!fsd)
return -ENOMEM;

- fsd->real_fops = (void *)((unsigned long)d_fsd &
- ~DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
+ fsd->real_fops = debugfs_clear_lowest_bit(d_fsd);
refcount_set(&fsd->active_users, 1);
init_completion(&fsd->active_users_drained);
if (cmpxchg(&dentry->d_fsdata, d_fsd, fsd) != d_fsd) {
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 7b975dbb2bb4..cc24e97686d0 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -211,7 +211,7 @@ static void debugfs_release_dentry(struct dentry *dentry)
{
void *fsd = dentry->d_fsdata;

- if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
+ if (!debugfs_test_lowest_bit(fsd))
kfree(dentry->d_fsdata);
}

@@ -398,8 +398,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,

inode->i_op = &debugfs_file_inode_operations;
inode->i_fop = proxy_fops;
- dentry->d_fsdata = (void *)((unsigned long)real_fops |
- DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
+ dentry->d_fsdata = debugfs_set_lowest_bit(real_fops);

d_instantiate(dentry, inode);
fsnotify_create(d_inode(dentry->d_parent), dentry);
@@ -679,7 +678,7 @@ static void __debugfs_file_removed(struct dentry *dentry)
*/
smp_mb();
fsd = READ_ONCE(dentry->d_fsdata);
- if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
+ if (debugfs_test_lowest_bit(fsd))
return;
if (!refcount_dec_and_test(&fsd->active_users))
wait_for_completion(&fsd->active_users_drained);
diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h
index f0d73d86cc1a..4dd6df4bc172 100644
--- a/fs/debugfs/internal.h
+++ b/fs/debugfs/internal.h
@@ -27,6 +27,9 @@ struct debugfs_fsdata {
* In order to distinguish between these two cases, a real fops
* pointer gets its lowest bit set.
*/
-#define DEBUGFS_FSDATA_IS_REAL_FOPS_BIT BIT(0)
+
+#define debugfs_set_lowest_bit(ptr) ((void *)((unsigned long)(ptr) | BIT(0)))
+#define debugfs_clear_lowest_bit(ptr) ((void *)((unsigned long)(ptr) & ~BIT(0)))
+#define debugfs_test_lowest_bit(ptr) ((unsigned long)(ptr) & BIT(0))

#endif /* _DEBUGFS_INTERNAL_H_ */
--
2.20.1
\
 
 \ /
  Last update: 2019-11-29 10:31    [W:0.117 / U:2.416 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site