Add a separate mutex to protect sysfs_open_dirent->buffers list. This
will allow performing sleepable operations while traversing
sysfs_buffers, which will be renamed to sysfs_open_file.
Note that currently sysfs_open_dirent->buffers list isn't being used
for anything and this patch doesn't make any functional difference.
It will be used to merge regular and bin file supports.
Signed-off-by: Tejun Heo <t...@kernel.org>
---
fs/sysfs/file.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 7dfcc33..499cff8 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -25,15 +25,17 @@
#include "sysfs.h"
/*
- * There's one sysfs_buffer for each open file and one
- * sysfs_open_dirent for each sysfs_dirent with one or more open
- * files.
+ * There's one sysfs_buffer for each open file and one sysfs_open_dirent
+ * for each sysfs_dirent with one or more open files.
*
- * filp->private_data points to sysfs_buffer and
- * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
- * is protected by sysfs_open_dirent_lock.
+ * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open is
+ * protected by sysfs_open_dirent_lock.
+ *
+ * filp->private_data points to sysfs_buffer which is chained at
+ * sysfs_open_dirent->buffers, which is protected by sysfs_open_file_mutex.
*/
static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
+static DEFINE_MUTEX(sysfs_open_file_mutex);
struct sysfs_open_dirent {
atomic_t refcnt;
@@ -272,6 +274,7 @@ static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
struct sysfs_open_dirent *od, *new_od = NULL;
retry:
+ mutex_lock(&sysfs_open_file_mutex);
spin_lock_irq(&sysfs_open_dirent_lock);
if (!sd->s_attr.open && new_od) {
@@ -286,6 +289,7 @@ static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
}
spin_unlock_irq(&sysfs_open_dirent_lock);
+ mutex_unlock(&sysfs_open_file_mutex);
if (od) {
kfree(new_od);
@@ -321,6 +325,7 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
struct sysfs_open_dirent *od = sd->s_attr.open;
unsigned long flags;
+ mutex_lock(&sysfs_open_file_mutex);
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
list_del(&buffer->list);
@@ -330,6 +335,7 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
od = NULL;
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
+ mutex_unlock(&sysfs_open_file_mutex);
kfree(od);
}
--
1.8.3.1
--
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