On 2013/7/4 15:41, Namhyung Kim wrote: > Hi Jovi, > > Just a few of dummy questions.. > > > On Thu, 4 Jul 2013 15:01:10 +0800, zhangwei wrote: >> Support multi-buffer on uprobe-based dynamic events by >> using ftrace_event_file. >> >> This patch is based kprobe-based dynamic events multibuffer >> support work initially, commited by Masami(commit 41a7dd420c), >> but revised as below: >> >> Oleg changed the kprobe-based multibuffer design from >> array-pointers of ftrace_event_file into simple list, >> so this patch also change to the list design. >> >> rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func, >> to synchronize with ftrace_event_file list add and delete. >> >> Even though we allow multi-uprobes instances now, >> but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive >> in probe_event_enable currently, this means we cannot allow >> one user is using uprobe-tracer, and another user is using >> perf-probe on same uprobe concurrently. >> (Perhaps this will be fix in future, kprobe dont't have this >> limitation now) > > So why does this limitation exist? Didn't we support this kind of thing > in the original code? > Yes, it existed(maybe not exist before uprobe pre-filter work), because uprobe filter is associated with trace_uprobe tightly at present, so we cannot assign TP_FLAG_PROFILE/TP_FLAG_TRACE for same trace_uprobe with different filter.
Perhaps we need to remove the limitation in future. >> >> Signed-off-by: zhangwei(Jovi) <[email protected]> >> Cc: Masami Hiramatsu <[email protected]> >> Cc: Frederic Weisbecker <[email protected]> >> Cc: Oleg Nesterov <[email protected]> >> Cc: Srikar Dronamraju <[email protected]> >> --- > [SNIP] >> + rcu_read_lock(); >> + list_for_each_entry(link, &tu->files, list) > > list_for_each_entry_rcu() ? > I haven't noticed this, thanks, I will update it. > >> + uprobe_trace_print(tu, 0, regs, link->file); >> + rcu_read_unlock(); >> + >> return 0; >> } >> >> static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long >> func, >> struct pt_regs *regs) >> { >> - uprobe_trace_print(tu, func, regs); >> + struct event_file_link *link; >> + >> + rcu_read_lock(); >> + list_for_each_entry(link, &tu->files, list) > > Ditto. > > >> + uprobe_trace_print(tu, func, regs, link->file); >> + rcu_read_unlock(); >> } > [SNIP] >> -static void probe_event_disable(struct trace_uprobe *tu, int flag) >> +static struct event_file_link * >> +find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file >> *file) >> +{ >> + struct event_file_link *link; >> + >> + list_for_each_entry(link, &tu->files, list) > > Not sure of this case. ;) > Yes, _rcu is not needed in here, it's only called in event disable serialized case. > Thanks, > Namhyung > >> + if (link->file == file) >> + return link; >> + >> + return NULL; >> +} >> + >> +static void >> +probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file) >> { >> if (!is_trace_uprobe_enabled(tu)) >> return; >> >> + if (file) { >> + struct event_file_link *link; >> + >> + link = find_event_file_link(tu, file); >> + if (!link) >> + return; >> + >> + list_del_rcu(&link->list); >> + /* synchronize with uprobe_trace_func/uretprobe_trace_func */ >> + synchronize_sched(); >> + kfree(link); >> + >> + if (!list_empty(&tu->files)) >> + return; >> + } >> + >> WARN_ON(!uprobe_filter_is_empty(&tu->filter)); >> >> uprobe_unregister(tu->inode, tu->offset, &tu->consumer); >> - tu->flags &= ~flag; >> + tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE; >> } >> >> static int uprobe_event_define_fields(struct ftrace_event_call *event_call) >> @@ -867,21 +947,22 @@ static >> int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg >> type, void *data) >> { >> struct trace_uprobe *tu = event->data; >> + struct ftrace_event_file *file = data; >> >> switch (type) { >> case TRACE_REG_REGISTER: >> - return probe_event_enable(tu, TP_FLAG_TRACE, NULL); >> + return probe_event_enable(tu, file, NULL); >> >> case TRACE_REG_UNREGISTER: >> - probe_event_disable(tu, TP_FLAG_TRACE); >> + probe_event_disable(tu, file); >> return 0; >> >> #ifdef CONFIG_PERF_EVENTS >> case TRACE_REG_PERF_REGISTER: >> - return probe_event_enable(tu, TP_FLAG_PROFILE, >> uprobe_perf_filter); >> + return probe_event_enable(tu, NULL, uprobe_perf_filter); >> >> case TRACE_REG_PERF_UNREGISTER: >> - probe_event_disable(tu, TP_FLAG_PROFILE); >> + probe_event_disable(tu, NULL); >> return 0; >> >> case TRACE_REG_PERF_OPEN: >> -- 1.7.9.7 > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
