From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: linux-next: build failure after merge of the rcu tree Date: Fri, 17 Jul 2015 11:53:21 -0700 Message-ID: <20150717185321.GA10554@linux.vnet.ibm.com> References: <20150716131423.4c849184@canb.auug.org.au> <20150716035138.GQ3717@linux.vnet.ibm.com> <20150717114046.GB5396@gmail.com> <20150717173528.GH3717@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150717173528.GH3717@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: Stephen Rothwell , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski List-Id: linux-next.vger.kernel.org On Fri, Jul 17, 2015 at 10:35:28AM -0700, Paul E. McKenney wrote: > On Fri, Jul 17, 2015 at 01:40:46PM +0200, Ingo Molnar wrote: > > > > * Paul E. McKenney wrote: > > > > > On Thu, Jul 16, 2015 at 01:14:23PM +1000, Stephen Rothwell wrote: > > > > Hi Paul, > > > > > > > > After merging the rcu tree, today's linux-next build (arm > > > > multi_v7_defconfig) failed like this: > > > > > > > > kernel/notifier.c: In function 'notify_die': > > > > kernel/notifier.c:547:2: error: implicit declaration of function 'rcu_lockdep_assert' [-Werror=implicit-function-declaration] > > > > rcu_lockdep_assert(rcu_is_watching(), > > > > ^ > > > > > > > > Caused by commit > > > > > > > > 02300fdb3e5f ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()") > > > > > > > > interacting with commit > > > > > > > > e727c7d7a11e ("notifiers, RCU: Assert that RCU is watching in notify_die()") > > > > > > > > [ and I also noted > > > > 0333a209cbf6 ("x86/irq, context_tracking: Document how IRQ context tracking works and add an RCU assertion") > > > > ] > > > > > > > > from the tip tree. > > > > > > Thank you in both cases! I suspect that more will follow, so is there > > > something I can do to make this easier? (Hard for me to patch stuff > > > that is not yet in the tree...) > > > > So we could keep the old macro around as well for such cases, and then remove it > > in v4.4 or so? > > Works for me! Will do. And here is a prototype patch, which I intend to merge with the existing patch that renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). I will also queue a revert of the patch below for 4.4. Thoughts? Thanx, Paul ------------------------------------------------------------------------ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 41c49b12fe6d..663d6e028c3d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -536,9 +536,29 @@ static inline int rcu_read_lock_sched_held(void) #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +/* Deprecate the rcu_lockdep_assert() macro. */ +static inline void __attribute((deprecated)) deprecate_rcu_lockdep_assert(void) +{ +} + #ifdef CONFIG_PROVE_RCU /** + * rcu_lockdep_assert - emit lockdep splat if specified condition not met + * @c: condition to check + * @s: informative message + */ +#define rcu_lockdep_assert(c, s) \ + do { \ + static bool __section(.data.unlikely) __warned; \ + deprecate_rcu_lockdep_assert(); \ + if (debug_lockdep_rcu_enabled() && !__warned && !(c)) { \ + __warned = true; \ + lockdep_rcu_suspicious(__FILE__, __LINE__, s); \ + } \ + } while (0) + +/** * RCU_LOCKDEP_WARN - emit lockdep splat if specified condition is met * @c: condition to check * @s: informative message @@ -575,6 +595,7 @@ static inline void rcu_preempt_sleep_check(void) #else /* #ifdef CONFIG_PROVE_RCU */ +#define rcu_lockdep_assert(c, s) deprecate_rcu_lockdep_assert() #define RCU_LOCKDEP_WARN(c, s) do { } while (0) #define rcu_sleep_check() do { } while (0)