All of lore.kernel.org
 help / color / mirror / Atom feed
From: Davidlohr Bueso <dave@stgolabs.net>
To: valdis.kletnieks@vt.edu, gregkh@linuxfoundation.org
Cc: dave@stgolabs.net, linux-kernel@vger.kernel.org
Subject: [PATCH v2] drivers/staging/exfat: Replace binary semaphores for mutexes
Date: Wed, 30 Oct 2019 07:49:16 -0700	[thread overview]
Message-ID: <20191030144916.10802-1-dave@stgolabs.net> (raw)
In-Reply-To: <20191029080521.GA494993@kroah.com>

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@stgolabs.net>
---
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


  reply	other threads:[~2019-10-30 14:50 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-28  2:45 [PATCH] drivers/staging/exfat: Replace binary semaphores for mutexes Davidlohr Bueso
2019-10-29  8:05 ` Greg KH
2019-10-30 14:49   ` Davidlohr Bueso [this message]
2019-10-30 15:40     ` [PATCH v2] " Valdis Klētnieks

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191030144916.10802-1-dave@stgolabs.net \
    --to=dave@stgolabs.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=valdis.kletnieks@vt.edu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.