diff options
Diffstat (limited to 'kernel/trace/trace_seq.c')
| -rw-r--r-- | kernel/trace/trace_seq.c | 45 |
1 files changed, 35 insertions, 10 deletions
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c index 1d84fcc78e3e..c158d65a8a88 100644 --- a/kernel/trace/trace_seq.c +++ b/kernel/trace/trace_seq.c @@ -13,10 +13,7 @@ * trace_seq_init() more than once to reset the trace_seq to start * from scratch. * - * The buffer size is currently PAGE_SIZE, although it may become dynamic - * in the future. - * - * A write to the buffer will either succed or fail. That is, unlike + * A write to the buffer will either succeed or fail. That is, unlike * sprintf() there will not be a partial write (well it may write into * the buffer but it wont update the pointers). This allows users to * try to write something into the trace_seq buffer and if it fails @@ -73,7 +70,7 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s) * @fmt: printf format string * * The tracer may use either sequence operations or its own - * copy to user routines. To simplify formating of a trace + * copy to user routines. To simplify formatting of a trace * trace_seq_printf() is used to store strings into a special * buffer (@s). Then the output may be either used by * the sequencer or pulled into another buffer. @@ -131,9 +128,10 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask); * trace_seq_vprintf - sequence printing of trace information * @s: trace sequence descriptor * @fmt: printf format string + * @args: Arguments for the format string * * The tracer may use either sequence operations or its own - * copy to user routines. To simplify formating of a trace + * copy to user routines. To simplify formatting of a trace * trace_seq_printf is used to store strings into a special * buffer (@s). Then the output may be either used by * the sequencer or pulled into another buffer. @@ -226,7 +224,7 @@ EXPORT_SYMBOL_GPL(trace_seq_puts); * @c: simple character to record * * The tracer may use either the sequence operations or its own - * copy to user routines. This function records a simple charater + * copy to user routines. This function records a simple character * into a special buffer (@s) for later retrieval by a sequencer * or other mechanism. */ @@ -348,7 +346,7 @@ int trace_seq_path(struct trace_seq *s, const struct path *path) EXPORT_SYMBOL_GPL(trace_seq_path); /** - * trace_seq_to_user - copy the squence buffer to user space + * trace_seq_to_user - copy the sequence buffer to user space * @s: trace sequence descriptor * @ubuf: The userspace memory location to copy to * @cnt: The amount to copy @@ -363,14 +361,18 @@ EXPORT_SYMBOL_GPL(trace_seq_path); * * On failure it returns -EBUSY if all of the content in the * sequence has been already read, which includes nothing in the - * sequenc (@s->len == @s->readpos). + * sequence (@s->len == @s->readpos). * * Returns -EFAULT if the copy to userspace fails. */ int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt) { + int ret; __trace_seq_init(s); - return seq_buf_to_user(&s->seq, ubuf, cnt); + ret = seq_buf_to_user(&s->seq, ubuf, s->readpos, cnt); + if (ret > 0) + s->readpos += ret; + return ret; } EXPORT_SYMBOL_GPL(trace_seq_to_user); @@ -403,3 +405,26 @@ int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str, return 1; } EXPORT_SYMBOL(trace_seq_hex_dump); + +/* + * trace_seq_acquire - acquire seq buffer with size len + * @s: trace sequence descriptor + * @len: size of buffer to be acquired + * + * acquire buffer with size of @len from trace_seq for output usage, + * user can fill string into that buffer. + * + * Returns start address of acquired buffer. + * + * it allow multiple usage in one trace output function call. + */ +char *trace_seq_acquire(struct trace_seq *s, unsigned int len) +{ + char *ret = trace_seq_buffer_ptr(s); + + if (!WARN_ON_ONCE(seq_buf_buffer_left(&s->seq) < len)) + seq_buf_commit(&s->seq, len); + + return ret; +} +EXPORT_SYMBOL(trace_seq_acquire); |