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Subject[PATCH] de-semaphorize smackfs
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While looking at the generic semaphore patch, I came to wonder what the
remaining semaphore users in the kernel were actually doing. After a
quick grep for down_interruptible(), smackfs remained at the bottom of
my screen. It seems like a straightforward mutex case - low-hanging
fruit. So here's a conversion patch; compile-tested only, but what
could go wrong?

jon

Convert smackfs from a semaphore to a mutex

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index afe7c9b..6e09cec 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -76,7 +76,7 @@ struct smk_list_entry *smack_list;
/*
* Disable concurrent writing open() operations
*/
-static struct semaphore smack_write_sem;
+static DEFINE_MUTEX(smack_write_mutex);

/*
* Values for parsing cipso rules
@@ -171,7 +171,7 @@ static int smk_open_load(struct inode *inode, struct file *file)
if ((file->f_flags & O_ACCMODE) == O_RDONLY)
return seq_open(file, &load_seq_ops);

- if (down_interruptible(&smack_write_sem))
+ if (mutex_lock_interruptible(&smack_write_mutex))
return -ERESTARTSYS;

return 0;
@@ -192,7 +192,7 @@ static int smk_release_load(struct inode *inode, struct file *file)
if ((file->f_flags & O_ACCMODE) == O_RDONLY)
return seq_release(inode, file);

- up(&smack_write_sem);
+ mutex_unlock(&smack_write_mutex);
return 0;
}

@@ -1011,7 +1011,7 @@ static int __init init_smk_fs(void)
}
}

- sema_init(&smack_write_sem, 1);
+ mutex_init(&smack_write_mutex);
smk_cipso_doi();
smk_unlbl_ambient(NULL);


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