diff options
| -rw-r--r-- | Documentation/filesystems/seq_file.txt | 22 | ||||
| -rw-r--r-- | fs/seq_file.c | 15 | ||||
| -rw-r--r-- | include/linux/seq_file.h | 15 |
3 files changed, 30 insertions, 22 deletions
diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt index 8ea3e90ace07..b797ed38de46 100644 --- a/Documentation/filesystems/seq_file.txt +++ b/Documentation/filesystems/seq_file.txt @@ -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 diff --git a/fs/seq_file.c b/fs/seq_file.c index 3857b720cb1b..353948ba1c5b 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -16,17 +16,6 @@ #include <asm/uaccess.h> #include <asm/page.h> - -/* - * seq_files have a buffer which can may overflow. When this happens a larger - * buffer is reallocated and all the data will be printed again. - * The overflow state is true when m->count == m->size. - */ -static bool seq_overflow(struct seq_file *m) -{ - return m->count == m->size; -} - static void seq_set_overflow(struct seq_file *m) { m->count = m->size; @@ -124,7 +113,7 @@ static int traverse(struct seq_file *m, loff_t offset) error = 0; m->count = 0; } - if (seq_overflow(m)) + if (seq_has_overflowed(m)) goto Eoverflow; if (pos + m->count > offset) { m->from = offset - pos; @@ -267,7 +256,7 @@ Fill: break; } err = m->op->show(m, p); - if (seq_overflow(m) || err) { + if (seq_has_overflowed(m) || err) { m->count = offs; if (likely(err <= 0)) break; diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index 52e0097f61f0..cf6a9daaaf6d 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -43,6 +43,21 @@ struct seq_operations { #define SEQ_SKIP 1 /** + * seq_has_overflowed - check if the buffer has overflowed + * @m: the seq_file handle + * + * seq_files have a buffer which may overflow. When this happens a larger + * buffer is reallocated and all the data will be printed again. + * The overflow state is true when m->count == m->size. + * + * Returns true if the buffer received more than it can hold. + */ +static inline bool seq_has_overflowed(struct seq_file *m) +{ + return m->count == m->size; +} + +/** * seq_get_buf - get buffer to write arbitrary data to * @m: the seq_file handle * @bufp: the beginning of the buffer is stored here |