Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754802Ab3HVX3r (ORCPT ); Thu, 22 Aug 2013 19:29:47 -0400 Received: from mga14.intel.com ([143.182.124.37]:47012 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754662Ab3HVX1n (ORCPT ); Thu, 22 Aug 2013 19:27:43 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,937,1367996400"; d="scan'208";a="350395746" From: Tom Zanussi To: rostedt@goodmis.org Cc: masami.hiramatsu.pt@hitachi.com, linux-kernel@vger.kernel.org, Tom Zanussi Subject: [PATCH v6 01/10] tracing: Add support for SOFT_DISABLE to syscall events Date: Thu, 22 Aug 2013 18:27:17 -0500 Message-Id: <2206e8bd6694105b1ba7e7faef9d725641f827d2.1377213245.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 1.7.11.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5442 Lines: 141 The original SOFT_DISABLE patches didn't add support for soft disable of syscall events; this adds it and paves the way for future patches allowing triggers to be added to syscall events, since triggers are built on top of SOFT_DISABLE. Add an array of ftrace_event_file pointers indexed by syscall number to the trace array and remove the existing enabled bitmaps, which as a result are now redundant. The ftrace_event_file structs in turn contain the soft disable flags we need for per-syscall soft disable accounting; later patches add additional 'trigger' flags and per-syscall triggers and filters. Signed-off-by: Tom Zanussi --- kernel/trace/trace.h | 4 ++-- kernel/trace/trace_syscalls.c | 36 ++++++++++++++++++++++++++++++------ 2 files changed, 32 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index fe39acd..b1227b9 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -192,8 +192,8 @@ struct trace_array { #ifdef CONFIG_FTRACE_SYSCALLS int sys_refcount_enter; int sys_refcount_exit; - DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls); - DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls); + struct ftrace_event_file *enter_syscall_files[NR_syscalls]; + struct ftrace_event_file *exit_syscall_files[NR_syscalls]; #endif int stop_count; int clock_id; diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 559329d..230cdb6 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -302,6 +302,7 @@ static int __init syscall_exit_define_fields(struct ftrace_event_call *call) static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) { struct trace_array *tr = data; + struct ftrace_event_file *ftrace_file; struct syscall_trace_enter *entry; struct syscall_metadata *sys_data; struct ring_buffer_event *event; @@ -314,7 +315,13 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0) return; - if (!test_bit(syscall_nr, tr->enabled_enter_syscalls)) + + /* Here we're inside the tp handler's rcu_read_lock (__DO_TRACE()) */ + ftrace_file = rcu_dereference_raw(tr->enter_syscall_files[syscall_nr]); + if (!ftrace_file) + return; + + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags)) return; sys_data = syscall_nr_to_meta(syscall_nr); @@ -345,6 +352,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret) { struct trace_array *tr = data; + struct ftrace_event_file *ftrace_file; struct syscall_trace_exit *entry; struct syscall_metadata *sys_data; struct ring_buffer_event *event; @@ -356,7 +364,13 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret) syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0) return; - if (!test_bit(syscall_nr, tr->enabled_exit_syscalls)) + + /* Here we're inside the tp handler's rcu_read_lock (__DO_TRACE()) */ + ftrace_file = rcu_dereference_raw(tr->exit_syscall_files[syscall_nr]); + if (!ftrace_file) + return; + + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags)) return; sys_data = syscall_nr_to_meta(syscall_nr); @@ -397,7 +411,7 @@ static int reg_event_syscall_enter(struct ftrace_event_file *file, if (!tr->sys_refcount_enter) ret = register_trace_sys_enter(ftrace_syscall_enter, tr); if (!ret) { - set_bit(num, tr->enabled_enter_syscalls); + rcu_assign_pointer(tr->enter_syscall_files[num], file); tr->sys_refcount_enter++; } mutex_unlock(&syscall_trace_lock); @@ -415,9 +429,14 @@ static void unreg_event_syscall_enter(struct ftrace_event_file *file, return; mutex_lock(&syscall_trace_lock); tr->sys_refcount_enter--; - clear_bit(num, tr->enabled_enter_syscalls); + rcu_assign_pointer(tr->enter_syscall_files[num], NULL); if (!tr->sys_refcount_enter) unregister_trace_sys_enter(ftrace_syscall_enter, tr); + /* + * Callers expect the event to be completely disabled on + * return, so wait for current handlers to finish. + */ + synchronize_sched(); mutex_unlock(&syscall_trace_lock); } @@ -435,7 +454,7 @@ static int reg_event_syscall_exit(struct ftrace_event_file *file, if (!tr->sys_refcount_exit) ret = register_trace_sys_exit(ftrace_syscall_exit, tr); if (!ret) { - set_bit(num, tr->enabled_exit_syscalls); + rcu_assign_pointer(tr->exit_syscall_files[num], file); tr->sys_refcount_exit++; } mutex_unlock(&syscall_trace_lock); @@ -453,9 +472,14 @@ static void unreg_event_syscall_exit(struct ftrace_event_file *file, return; mutex_lock(&syscall_trace_lock); tr->sys_refcount_exit--; - clear_bit(num, tr->enabled_exit_syscalls); + rcu_assign_pointer(tr->exit_syscall_files[num], NULL); if (!tr->sys_refcount_exit) unregister_trace_sys_exit(ftrace_syscall_exit, tr); + /* + * Callers expect the event to be completely disabled on + * return, so wait for current handlers to finish. + */ + synchronize_sched(); mutex_unlock(&syscall_trace_lock); } -- 1.7.11.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/