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    SubjectRe: [PATCH -tip -v11 08/11] tracing: add kprobe-based event tracer
    > +static __kprobes unsigned long fetch_memory(struct pt_regs *regs, void *addr)
    > +{
    > + unsigned long retval;

    need a space after local variable declarations.

    > + if (probe_kernel_address(addr, retval))
    > + return 0;
    > + return retval;
    > +}
    > +
    > +static __kprobes unsigned long fetch_argument(struct pt_regs *regs, void *num)
    > +{
    > + return regs_get_argument_nth(regs, (unsigned int)((unsigned long)num));
    > +}
    > +
    > +static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
    > + void *dummy)
    > +{
    > + return regs_return_value(regs);
    > +}
    > +
    > +static __kprobes unsigned long fetch_ip(struct pt_regs *regs, void *dummy)
    > +{
    > + return instruction_pointer(regs);
    > +}
    > +
    > +/* Memory fetching by symbol */
    > +struct symbol_cache {
    > + char *symbol;
    > + long offset;
    > + unsigned long addr;
    > +};
    > +
    > +static unsigned long update_symbol_cache(struct symbol_cache *sc)
    > +{
    > + sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
    > + if (sc->addr)
    > + sc->addr += sc->offset;
    > + return sc->addr;
    > +}
    > +
    > +static void free_symbol_cache(struct symbol_cache *sc)
    > +{
    > + kfree(sc->symbol);
    > + kfree(sc);
    > +}
    > +
    > +static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
    > +{
    > + struct symbol_cache *sc;

    ditto.

    and in some other places

    > + if (!sym || strlen(sym) == 0)
    > + return NULL;
    > + sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
    > + if (!sc)
    > + return NULL;
    > +
    > + sc->symbol = kstrdup(sym, GFP_KERNEL);
    > + if (!sc->symbol) {
    > + kfree(sc);
    > + return NULL;
    > + }
    > + sc->offset = offset;
    > +
    > + update_symbol_cache(sc);
    > + return sc;
    > +}

    ...

    > +static int probes_seq_show(struct seq_file *m, void *v)
    > +{
    > + struct trace_probe *tp = v;
    > + int i, ret;
    > + char buf[MAX_ARGSTR_LEN + 1];
    > +
    > + if (tp == NULL)
    > + return 0;
    > +

    redundant check. tp won't be NULL.

    > + seq_printf(m, "%c", probe_is_return(tp) ? 'r' : 'p');
    > + if (tp->call.name)
    > + seq_printf(m, ":%s", tp->call.name);
    > +
    > + if (tp->symbol)
    > + seq_printf(m, " %s%+ld", probe_symbol(tp), probe_offset(tp));
    > + else
    > + seq_printf(m, " 0x%p", probe_address(tp));
    > +
    > + for (i = 0; i < tp->nr_args; i++) {
    > + ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
    > + if (ret) {
    > + pr_warning("Argument%d is too long.\n", i);
    > + break;
    > + }
    > + seq_printf(m, " %s", buf);
    > + }
    > + seq_printf(m, "\n");
    > + return 0;
    > +}

    ...

    > +static ssize_t probes_write(struct file *file, const char __user *buffer,
    > + size_t count, loff_t *ppos)
    > +{
    > + char *kbuf, *tmp;
    > + int ret;
    > + size_t done;
    > + size_t size;
    > +
    > + if (!count || count < 0)
    > + return 0;

    count is unsigned, so won't < 0. Also I don't think you
    need to treat (count == 0) specially.

    > +
    > + kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);

    should be kmalloc(WRITE_BUFSIZE+1), or...

    > + if (!kbuf)
    > + return -ENOMEM;
    > +
    > + ret = done = 0;
    > + do {
    > + size = count - done;
    > + if (size > WRITE_BUFSIZE)
    > + size = WRITE_BUFSIZE;

    if (size >= WRITE_BUFSIZE)
    size = WRITE_BUFSIZE - 1;

    > + if (copy_from_user(kbuf, buffer + done, size)) {
    > + ret = -EFAULT;
    > + goto out;
    > + }
    > + kbuf[size] = '\0';
    > + tmp = strchr(kbuf, '\n');
    > + if (!tmp) {
    > + pr_warning("Line length is too long: "
    > + "Should be less than %d.", WRITE_BUFSIZE);
    > + ret = -EINVAL;
    > + goto out;
    > + }
    > + *tmp = '\0';
    > + size = tmp - kbuf + 1;
    > + done += size;
    > + /* Remove comments */
    > + tmp = strchr(kbuf, '#');
    > + if (tmp)
    > + *tmp = '\0';
    > +
    > + ret = command_trace_probe(kbuf);
    > + if (ret)
    > + goto out;
    > +
    > + } while (done < count);
    > + ret = done;
    > +out:
    > + kfree(kbuf);
    > + return ret;
    > +}

    ...

    > +enum print_line_t
    > +print_kretprobe_event(struct trace_iterator *iter, int flags)
    > +{
    > + struct kretprobe_trace_entry *field;
    > + struct trace_seq *s = &iter->seq;
    > + int i;
    > +
    > + trace_assign_type(field, iter->ent);
    > +
    > + if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
    > + goto partial;
    > +

    can't we use %pF?

    > + if (!trace_seq_puts(s, " <- "))
    > + goto partial;
    > +
    > + if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
    > + goto partial;
    > +

    and $pf?

    > + if (!trace_seq_puts(s, ":"))
    > + goto partial;
    > +

    so all the above:

    trace_seq_puts(s, "%pF <- %pf:", (void *)field->ret_ip,
    (void *)field->func);

    > + for (i = 0; i < field->nargs; i++)
    > + if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
    > + goto partial;
    > +
    > + if (!trace_seq_puts(s, "\n"))
    > + goto partial;
    > +
    > + return TRACE_TYPE_HANDLED;
    > +partial:
    > + return TRACE_TYPE_PARTIAL_LINE;
    > +}


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      Last update: 2009-07-10 09:17    [W:0.062 / U:0.512 seconds]
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