include/linux/seq_file.h: introduce DEFINE_SEQ_ATTRIBUTE() helper macro

Patch series "seq_file: Introduce DEFINE_SEQ_ATTRIBUTE() helper macro".

As discussed in
https://lore.kernel.org/lkml/20191129222310.GA3712618@kroah.com/, we could
introduce a new helper macro to reduce losts of boilerplate code, vmstat
and kprobes is the example which covert to use it, if this is accepted, I
will send out more cleanups.

This patch (of 3):

Introduce DEFINE_SEQ_ATTRIBUTE() helper macro to decrease code duplication.

[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: http://lkml.kernel.org/r/20200509064031.181091-1-wangkefeng.wang@huawei.com
Link: http://lkml.kernel.org/r/20200509064031.181091-2-wangkefeng.wang@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 1672cf6f7614554e5cbc35a7d13458992c9101dd..813614d4b71fbcfdcf84ac21b8709949d51e5a3e 100644 (file)
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -145,6 +145,25 @@ void *__seq_open_private(struct file *, const struct seq_operations *, int);
 int seq_open_private(struct file *, const struct seq_operations *, int);
 int seq_release_private(struct inode *, struct file *);
 
+#define DEFINE_SEQ_ATTRIBUTE(__name)                                   \
+static int __name ## _open(struct inode *inode, struct file *file)     \
+{                                                                      \
+       int ret = seq_open(file, &__name ## _sops);                     \
+       if (!ret && inode->i_private) {                                 \
+               struct seq_file *seq_f = file->private_data;            \
+               seq_f->private = inode->i_private;                      \
+       }                                                               \
+       return ret;                                                     \
+}                                                                      \
+                                                                       \
+static const struct file_operations __name ## _fops = {                        \
+       .owner          = THIS_MODULE,                                  \
+       .open           = __name ## _open,                              \
+       .read           = seq_read,                                     \
+       .llseek         = seq_lseek,                                    \
+       .release        = seq_release,                                  \
+}
+
 #define DEFINE_SHOW_ATTRIBUTE(__name)                                  \
 static int __name ## _open(struct inode *inode, struct file *file)     \
 {                                                                      \