Messages in this thread | | | Subject | Re: [PATCHv2 1/3] tracing - buf iterator definition, parsing function | From | Steven Rostedt <> | Date | Tue, 08 Sep 2009 09:47:51 -0400 |
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On Sat, 2009-09-05 at 03:12 +0200, jolsa@redhat.com wrote: > Defined 'trace_biter' structure to carry the properties of the input, > through the multiple writes. > > The 'trace_get_user' reads the user incput string separated by space
incput?
> (matched by isspace(ch). For each string found the 'struct trace_biter' > iterator is updated, and the function returns. > > wbr, > jirka > > Signed-off-by: Jiri Olsa <jolsa@redhat.com> > > --- > kernel/trace/trace.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++ > kernel/trace/trace.h | 48 +++++++++++++++++++++++++++++ > 2 files changed, 131 insertions(+), 0 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index af15008..8cf8f99 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -335,6 +335,89 @@ static struct { > > int trace_clock_id; > > +/* > + * trace_get_user - reads the user incput string separated by space
incput again?
> + * (matched by isspace(ch)) > + * > + * For each string found the 'struct trace_biter' iterator is updated, > + * and the function returns. > + * > + * Returns number of bytes read. > + * > + * see kernel/trace/trace.h for 'struct trace_biter' details. > + */ > +int trace_get_user(struct trace_biter *biter, const char __user *ubuf, > + size_t cnt, loff_t *ppos) > +{ > + char ch; > + size_t read = 0; > + ssize_t ret; > + > + if (!*ppos) > + TRACE_BITER_CLEAR(biter); > + > + ret = get_user(ch, ubuf++); > + if (ret) > + goto out; > + > + read++; > + cnt--; > + > + /* > + * If the parser haven't finished with the last write, > + * continue reading the user input without skipping spaces. > + */ > + if (!biter->cont) { > + /* skip white space */ > + while (cnt && isspace(ch)) { > + ret = get_user(ch, ubuf++); > + if (ret) > + goto out; > + read++; > + cnt--; > + } > + > + /* only spaces were written */ > + if (isspace(ch)) { > + *ppos += read; > + ret = read; > + goto out; > + } > + > + biter->idx = 0; > + } > + > + /* read the non-space input */ > + while (cnt && !isspace(ch)) { > + if (biter->idx < biter->size) > + biter->buffer[biter->idx++] = ch; > + else { > + ret = -EINVAL; > + goto out; > + } > + ret = get_user(ch, ubuf++); > + if (ret) > + goto out; > + read++; > + cnt--; > + } > + > + /* We either got finished input or we have to wait for another call. */ > + if (isspace(ch)) { > + biter->buffer[biter->idx] = 0; > + biter->cont = 0; > + } else { > + biter->cont = 1; > + biter->buffer[biter->idx++] = ch; > + } > + > + *ppos += read; > + ret = read; > + > +out: > + return ret; > +} > + > ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt) > { > int len; > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index d881015..d4e38e8 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -652,6 +652,54 @@ static inline int ftrace_trace_task(struct task_struct *task) > #endif > > /* > + * struct trace_biter - servers for reading the user input separated by spaces > + * @cont: set if the input is not complete - no final space char was found > + * @buffer: holds the parsed user input > + * @idx: user input lenght
length
> + * @size: buffer size > + */ > +struct trace_biter { > + bool cont; > + char *buffer; > + unsigned idx; > + unsigned size; > +}; > + > +#define TRACE_BITER_LOADED(biter) (biter->idx) > +#define TRACE_BITER_CONT(biter) (biter->cont) > +#define TRACE_BITER_CLEAR(biter) \ > +do { \ > + biter->cont = false; \ > + biter->idx = 0; \ > +} while(0) > + > +/* > + * trace_biter_alloc - allocates the buffer for trace buffer iterator > + */ > +static inline int trace_biter_alloc(struct trace_biter *biter, int size) > +{ > + memset(biter, 0, sizeof(*biter)); > + > + biter->buffer = kmalloc(size, GFP_KERNEL); > + if (!biter->buffer) > + return 1; > + > + biter->size = size; > + return 0; > +}
I don't see any reason that trace_biter_alloc is as static inline in a header file. It should be a normal function in trace.c
> + > +/* > + * trace_biter_free - frees the buffer for trace buffer iterator > + */ > +static inline void trace_biter_free(struct trace_biter *biter) > +{ > + kfree(biter->buffer); > +}
trace_biter_free too.
But I also hate the name "biter", looks too much like "bitter". How about something like "trace_parser", or "trace_string_reader"?
-- Steve
> + > +extern int trace_get_user(struct trace_biter *biter, const char __user *ubuf, > + size_t cnt, loff_t *ppos); > + > +/* > * trace_iterator_flags is an enumeration that defines bit > * positions into trace_flags that controls the output. > *
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