[PATCH v2] drivers/staging/exfat: Replace binary semaphores for mutexes
From: Davidlohr Bueso
Date: Wed Oct 30 2019 - 10:51:16 EST
At a slight footprint cost (24 vs 32 bytes), mutexes are more optimal
than semaphores; it's also a nicer interface for mutual exclusion,
which is why they are encouraged over binary semaphores, when possible.
For both v_sem and z_sem, their semantics imply traditional lock
ownership; that is, the lock owner is the same for both lock/unlock
operations. Therefore it is safe to convert.
Signed-off-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>
---
This is part of further reducing semaphore users in the kernel.
v2: removed whitespace
drivers/staging/exfat/exfat.h | 2 +-
drivers/staging/exfat/exfat_super.c | 84 ++++++++++++++++++-------------------
2 files changed, 43 insertions(+), 43 deletions(-)
diff --git a/drivers/staging/exfat/exfat.h b/drivers/staging/exfat/exfat.h
index 6c12f2d79f4d..95c02f55de60 100644
--- a/drivers/staging/exfat/exfat.h
+++ b/drivers/staging/exfat/exfat.h
@@ -618,7 +618,7 @@ struct fs_info_t {
u32 dev_ejected; /* block device operation error flag */
struct fs_func *fs_func;
- struct semaphore v_sem;
+ struct mutex v_mutex;
/* FAT cache */
struct buf_cache_t FAT_cache_array[FAT_CACHE_SIZE];
diff --git a/drivers/staging/exfat/exfat_super.c b/drivers/staging/exfat/exfat_super.c
index 5f6caee819a6..e9e9868cae85 100644
--- a/drivers/staging/exfat/exfat_super.c
+++ b/drivers/staging/exfat/exfat_super.c
@@ -283,7 +283,7 @@ static const struct dentry_operations exfat_dentry_ops = {
.d_compare = exfat_cmp,
};
-static DEFINE_SEMAPHORE(z_sem);
+static DEFINE_MUTEX(z_mutex);
static inline void fs_sync(struct super_block *sb, bool do_sync)
{
@@ -352,11 +352,11 @@ static int ffsMountVol(struct super_block *sb)
pr_info("[EXFAT] trying to mount...\n");
- down(&z_sem);
+ mutex_lock(&z_mutex);
buf_init(sb);
- sema_init(&p_fs->v_sem, 1);
+ mutex_init(&p_fs->v_mutex);
p_fs->dev_ejected = 0;
/* open the block device */
@@ -441,7 +441,7 @@ static int ffsMountVol(struct super_block *sb)
pr_info("[EXFAT] mounted successfully\n");
out:
- up(&z_sem);
+ mutex_unlock(&z_mutex);
return ret;
}
@@ -453,10 +453,10 @@ static int ffsUmountVol(struct super_block *sb)
pr_info("[EXFAT] trying to unmount...\n");
- down(&z_sem);
+ mutex_lock(&z_mutex);
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
fs_sync(sb, false);
fs_set_vol_flags(sb, VOL_CLEAN);
@@ -480,8 +480,8 @@ static int ffsUmountVol(struct super_block *sb)
buf_shutdown(sb);
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
- up(&z_sem);
+ mutex_unlock(&p_fs->v_mutex);
+ mutex_unlock(&z_mutex);
pr_info("[EXFAT] unmounted successfully\n");
@@ -498,7 +498,7 @@ static int ffsGetVolInfo(struct super_block *sb, struct vol_info_t *info)
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
if (p_fs->used_clusters == UINT_MAX)
p_fs->used_clusters = p_fs->fs_func->count_used_clusters(sb);
@@ -513,7 +513,7 @@ static int ffsGetVolInfo(struct super_block *sb, struct vol_info_t *info)
err = FFS_MEDIAERR;
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return err;
}
@@ -524,7 +524,7 @@ static int ffsSyncVol(struct super_block *sb, bool do_sync)
struct fs_info_t *p_fs = &(EXFAT_SB(sb)->fs_info);
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* synchronize the file system */
fs_sync(sb, do_sync);
@@ -534,7 +534,7 @@ static int ffsSyncVol(struct super_block *sb, bool do_sync)
err = FFS_MEDIAERR;
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return err;
}
@@ -561,7 +561,7 @@ static int ffsLookupFile(struct inode *inode, char *path, struct file_id_t *fid)
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* check the validity of directory name in the given pathname */
ret = resolve_path(inode, path, &dir, &uni_name);
@@ -635,7 +635,7 @@ static int ffsLookupFile(struct inode *inode, char *path, struct file_id_t *fid)
ret = FFS_MEDIAERR;
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -654,7 +654,7 @@ static int ffsCreateFile(struct inode *inode, char *path, u8 mode,
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* check the validity of directory name in the given pathname */
ret = resolve_path(inode, path, &dir, &uni_name);
@@ -676,7 +676,7 @@ static int ffsCreateFile(struct inode *inode, char *path, u8 mode,
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -703,7 +703,7 @@ static int ffsReadFile(struct inode *inode, struct file_id_t *fid, void *buffer,
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* check if the given file ID is opened */
if (fid->type != TYPE_FILE) {
@@ -800,7 +800,7 @@ static int ffsReadFile(struct inode *inode, struct file_id_t *fid, void *buffer,
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -833,7 +833,7 @@ static int ffsWriteFile(struct inode *inode, struct file_id_t *fid,
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* check if the given file ID is opened */
if (fid->type != TYPE_FILE) {
@@ -1057,7 +1057,7 @@ static int ffsWriteFile(struct inode *inode, struct file_id_t *fid,
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1080,7 +1080,7 @@ static int ffsTruncateFile(struct inode *inode, u64 old_size, u64 new_size)
new_size);
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* check if the given file ID is opened */
if (fid->type != TYPE_FILE) {
@@ -1190,7 +1190,7 @@ static int ffsTruncateFile(struct inode *inode, u64 old_size, u64 new_size)
out:
pr_debug("%s exited (%d)\n", __func__, ret);
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1238,7 +1238,7 @@ static int ffsMoveFile(struct inode *old_parent_inode, struct file_id_t *fid,
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
update_parent_info(fid, old_parent_inode);
@@ -1336,7 +1336,7 @@ static int ffsMoveFile(struct inode *old_parent_inode, struct file_id_t *fid,
ret = FFS_MEDIAERR;
out2:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1355,7 +1355,7 @@ static int ffsRemoveFile(struct inode *inode, struct file_id_t *fid)
return FFS_INVALIDFID;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
dir.dir = fid->dir.dir;
dir.size = fid->dir.size;
@@ -1398,7 +1398,7 @@ static int ffsRemoveFile(struct inode *inode, struct file_id_t *fid)
ret = FFS_MEDIAERR;
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1433,7 +1433,7 @@ static int ffsSetAttr(struct inode *inode, u32 attr)
}
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* get the directory entry of given file */
if (p_fs->vol_type == EXFAT) {
@@ -1487,7 +1487,7 @@ static int ffsSetAttr(struct inode *inode, u32 attr)
ret = FFS_MEDIAERR;
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1511,7 +1511,7 @@ static int ffsReadStat(struct inode *inode, struct dir_entry_t *info)
pr_debug("%s entered\n", __func__);
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
if (is_dir) {
if ((fid->dir.dir == p_fs->root_dir) &&
@@ -1640,7 +1640,7 @@ static int ffsReadStat(struct inode *inode, struct dir_entry_t *info)
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
pr_debug("%s exited successfully\n", __func__);
return ret;
@@ -1661,7 +1661,7 @@ static int ffsWriteStat(struct inode *inode, struct dir_entry_t *info)
pr_debug("%s entered (inode %p info %p\n", __func__, inode, info);
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
if (is_dir) {
if ((fid->dir.dir == p_fs->root_dir) &&
@@ -1727,7 +1727,7 @@ static int ffsWriteStat(struct inode *inode, struct dir_entry_t *info)
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
pr_debug("%s exited (%d)\n", __func__, ret);
@@ -1753,7 +1753,7 @@ static int ffsMapCluster(struct inode *inode, s32 clu_offset, u32 *clu)
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
fid->rwoffset = (s64)(clu_offset) << p_fs->cluster_size_bits;
@@ -1881,7 +1881,7 @@ static int ffsMapCluster(struct inode *inode, s32 clu_offset, u32 *clu)
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1905,7 +1905,7 @@ static int ffsCreateDir(struct inode *inode, char *path, struct file_id_t *fid)
return FFS_ERROR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
/* check the validity of directory name in the given old pathname */
ret = resolve_path(inode, path, &dir, &uni_name);
@@ -1925,7 +1925,7 @@ static int ffsCreateDir(struct inode *inode, char *path, struct file_id_t *fid)
ret = FFS_MEDIAERR;
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -1955,7 +1955,7 @@ static int ffsReadDir(struct inode *inode, struct dir_entry_t *dir_entry)
return FFS_PERMISSIONERR;
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
if (fid->entry == -1) {
dir.dir = p_fs->root_dir;
@@ -2124,7 +2124,7 @@ static int ffsReadDir(struct inode *inode, struct dir_entry_t *dir_entry)
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -2154,7 +2154,7 @@ static int ffsRemoveDir(struct inode *inode, struct file_id_t *fid)
}
/* acquire the lock for file system critical section */
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
clu_to_free.dir = fid->start_clu;
clu_to_free.size = (s32)((fid->size - 1) >> p_fs->cluster_size_bits) + 1;
@@ -2187,7 +2187,7 @@ static int ffsRemoveDir(struct inode *inode, struct file_id_t *fid)
out:
/* release the lock for file system critical section */
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
return ret;
}
@@ -3983,10 +3983,10 @@ static void exfat_debug_kill_sb(struct super_block *sb)
* invalidate_bdev drops all device cache include
* dirty. We use this to simulate device removal.
*/
- down(&p_fs->v_sem);
+ mutex_lock(&p_fs->v_mutex);
FAT_release_all(sb);
buf_release_all(sb);
- up(&p_fs->v_sem);
+ mutex_unlock(&p_fs->v_mutex);
invalidate_bdev(bdev);
}
--
2.16.4