Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761432AbaGRNFD (ORCPT ); Fri, 18 Jul 2014 09:05:03 -0400 Received: from bband-dyn38.178-41-141.t-com.sk ([178.41.141.38]:17232 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932307AbaGRNDT (ORCPT ); Fri, 18 Jul 2014 09:03:19 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , Steven Rostedt , Jiri Slaby Subject: [PATCH 3.12 057/170] tracing: Fix syscall_*regfunc() vs copy_process() race Date: Fri, 18 Jul 2014 14:11:02 +0200 Message-Id: <1855b4bde5c72f1da35088452226b458bdadadb4.1405685481.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.0 In-Reply-To: <48e8cad86bb1241c08bdaa80db022c25068ff8e0.1405685481.git.jslaby@suse.cz> References: <48e8cad86bb1241c08bdaa80db022c25068ff8e0.1405685481.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleg Nesterov 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 4af4206be2bd1933cae20c2b6fb2058dbc887f7c upstream. syscall_regfunc() and syscall_unregfunc() should set/clear TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race with copy_process() and miss the new child which was not added to the process/thread lists yet. Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT under tasklist. Link: http://lkml.kernel.org/p/20140413185854.GB20668@redhat.com Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints" Acked-by: Frederic Weisbecker Acked-by: Paul E. McKenney Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt Signed-off-by: Jiri Slaby --- include/trace/syscall.h | 15 +++++++++++++++ kernel/fork.c | 2 ++ 2 files changed, 17 insertions(+) diff --git a/include/trace/syscall.h b/include/trace/syscall.h index fed853f3d7aa..9674145e2f6a 100644 --- a/include/trace/syscall.h +++ b/include/trace/syscall.h @@ -4,6 +4,7 @@ #include #include #include +#include #include @@ -32,4 +33,18 @@ struct syscall_metadata { struct ftrace_event_call *exit_event; }; +#if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS) +static inline void syscall_tracepoint_update(struct task_struct *p) +{ + if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + set_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT); + else + clear_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT); +} +#else +static inline void syscall_tracepoint_update(struct task_struct *p) +{ +} +#endif + #endif /* _TRACE_SYSCALL_H */ diff --git a/kernel/fork.c b/kernel/fork.c index c873bd081e09..143962949bed 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1490,7 +1490,9 @@ static struct task_struct *copy_process(unsigned long clone_flags, total_forks++; spin_unlock(¤t->sighand->siglock); + syscall_tracepoint_update(p); write_unlock_irq(&tasklist_lock); + proc_fork_connector(p); cgroup_post_fork(p); if (clone_flags & CLONE_THREAD) -- 2.0.0 -- 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/