Commit 8ce74dd6 authored by Al Viro's avatar Al Viro
Browse files

Merge tag 'trace-seq-file-cleanup' of... 

Merge tag 'trace-seq-file-cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into for-next

Pull the beginning of seq_file cleanup from Steven:
  "I'm looking to clean up the seq_file code and to eventually merge the
  trace_seq code with seq_file as well, since they basically do the same thing.

  Part of this process is to remove the return code of seq_printf() and friends
  as they are rather inconsistent. It is better to use the new function
  seq_has_overflowed() if you want to stop processing when the buffer
  is full. Note, if the buffer is full, the seq_file code will throw away
  the contents, allocate a bigger buffer, and then call your code again
  to fill in the data. The only thing that breaking out of the function
  early does is to save a little time which is probably never noticed.

  I started with patches from Joe Perches and modified them as well.
  There's many more places that need to be updated before we can convert
  seq_printf() and friends to return void. But this patch set introduces
  the seq_has_overflowed() and does some initial updates."
parents 78d28e65 9761536e

Documentation/filesystems/debugfs.txt

+1 −1
Original line number Diff line number Diff line
@@ -140,7 +140,7 @@ file. 
				     struct dentry *parent,

				     struct debugfs_regset32 *regset);



    int debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,

    void debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,

			 int nregs, void __iomem *base, char *prefix);



The "base" argument may be 0, but you may want to build the reg32 array

Documentation/filesystems/seq_file.txt

+13 −9
Original line number Diff line number Diff line
@@ -180,23 +180,19 @@ output must be passed to the seq_file code. Some utility functions have 
been defined which make this task easy.



Most code will simply use seq_printf(), which works pretty much like

printk(), but which requires the seq_file pointer as an argument. It is

common to ignore the return value from seq_printf(), but a function

producing complicated output may want to check that value and quit if

something non-zero is returned; an error return means that the seq_file

buffer has been filled and further output will be discarded.

printk(), but which requires the seq_file pointer as an argument.



For straight character output, the following functions may be used:



	int seq_putc(struct seq_file *m, char c);

	int seq_puts(struct seq_file *m, const char *s);

	int seq_escape(struct seq_file *m, const char *s, const char *esc);

	seq_putc(struct seq_file *m, char c);

	seq_puts(struct seq_file *m, const char *s);

	seq_escape(struct seq_file *m, const char *s, const char *esc);



The first two output a single character and a string, just like one would

expect. seq_escape() is like seq_puts(), except that any character in s

which is in the string esc will be represented in octal form in the output.



There is also a pair of functions for printing filenames:

There are also a pair of functions for printing filenames:



	int seq_path(struct seq_file *m, struct path *path, char *esc);

	int seq_path_root(struct seq_file *m, struct path *path,
@@ -209,6 +205,14 @@ root is desired, it can be used with seq_path_root(). Note that, if it 
turns out that path cannot be reached from root, the value of root will be

changed in seq_file_root() to a root which *does* work.



A function producing complicated output may want to check

	bool seq_has_overflowed(struct seq_file *m);

and avoid further seq_<output> calls if true is returned.



A true return from seq_has_overflowed means that the seq_file buffer will

be discarded and the seq_show function will attempt to allocate a larger

buffer and retry printing.





Making it all work

Documentation/filesystems/vfs.txt

+1 −1
Original line number Diff line number Diff line
@@ -835,7 +835,7 @@ struct file_operations { 
	ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int);

	int (*setlease)(struct file *, long arg, struct file_lock **, void **);

	long (*fallocate)(struct file *, int mode, loff_t offset, loff_t len);

	int (*show_fdinfo)(struct seq_file *m, struct file *f);

	void (*show_fdinfo)(struct seq_file *m, struct file *f);

};



Again, all methods are called without any locks being held, unless

drivers/net/tun.c

+2 −2
Original line number Diff line number Diff line
@@ -2209,7 +2209,7 @@ static int tun_chr_close(struct inode *inode, struct file *file) 
}



#ifdef CONFIG_PROC_FS

static int tun_chr_show_fdinfo(struct seq_file *m, struct file *f)

static void tun_chr_show_fdinfo(struct seq_file *m, struct file *f)

{

	struct tun_struct *tun;

	struct ifreq ifr;
@@ -2225,7 +2225,7 @@ static int tun_chr_show_fdinfo(struct seq_file *m, struct file *f) 
	if (tun)

		tun_put(tun);



	return seq_printf(m, "iff:\t%s\n", ifr.ifr_name);

	seq_printf(m, "iff:\t%s\n", ifr.ifr_name);

}

#endif

fs/debugfs/file.c

+8 −7
Original line number Diff line number Diff line
@@ -692,18 +692,19 @@ EXPORT_SYMBOL_GPL(debugfs_create_u32_array); 
 * because some peripherals have several blocks of identical registers,

 * for example configuration of dma channels

 */

int debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,

void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,

			  int nregs, void __iomem *base, char *prefix)

{

	int i, ret = 0;

	int i;



	for (i = 0; i < nregs; i++, regs++) {

		if (prefix)

			ret += seq_printf(s, "%s", prefix);

		ret += seq_printf(s, "%s = 0x%08x\n", regs->name,

			seq_printf(s, "%s", prefix);

		seq_printf(s, "%s = 0x%08x\n", regs->name,

			   readl(base + regs->offset));

		if (seq_has_overflowed(s))

			break;

	}

	return ret;

}

EXPORT_SYMBOL_GPL(debugfs_print_regs32);

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