lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:	Thu,  7 Aug 2014 15:51:04 +0100
From:	Rob Jones <>
Subject: [PATCH] seq_file: Document seq_open_private(), seq_release_private()

Despite the fact that these functions have been around for years, they are
little used (only 15 uses in 13 files at the preseht time) even though
many other files use work-arounds to achieve the same result.

By documenting them, hopefully they will become more widely used.

Signed-off-by: Rob Jones <>
 Documentation/filesystems/seq_file.txt |   33 ++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt
index a1e2e0d..c9b8f6b 100644
--- a/Documentation/filesystems/seq_file.txt
+++ b/Documentation/filesystems/seq_file.txt
@@ -226,6 +226,39 @@ be used for more than one file, you can store an arbitrary pointer in the
 private field of the seq_file structure; that value can then be retrieved
 by the iterator functions.
+There is also a wrapper function to seq_open(), seq_open_private(). It
+kmallocs a zero filled block of memory and stores a pointer to it in the
+private field of the seq_file structure, returning 0 on success. The
+block size is specified in a third parameter to the function, e.g.:
+	static int ct_open(struct inode *inode, struct file *file)
+	{
+		return seq_open_private(file, &ct_seq_ops,
+					sizeof(struct mystruct);
+	}
+There is also a variant function, __seq_open_private(), which is functionally
+identical except that, if successful, it returns the pointer to the allocated
+memory block, allowing further initialisation e.g.:
+	static int ct_open(struct inode *inode, struct file *file)
+	{
+		struct mystruct *p =
+			__seq_open_private(file, &ct_seq_ops, sizeof(*p);
+		if (!p)
+			return -ENOMEM;
+		p->foo = bar; /* initialize my stuff */
+			...
+		p->baz = true;
+		return 0;
+	}
+A corresponding close function, seq_release_private() is available which
+frees the memory allocated in the corresponding open.
 The other operations of interest - read(), llseek(), and release() - are
 all implemented by the seq_file code itself. So a virtual file's
 file_operations structure will look like:

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists