From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: linux-next: build failure after merge of the scsi-mkp tree Date: Wed, 6 Dec 2017 20:42:22 -0800 Message-ID: <20171207044222.GK7829@linux.vnet.ibm.com> References: <20171207145728.57cd9ac4@canb.auug.org.au> <1512619169.3298.3.camel@wdc.com> <20171207152521.0036b131@canb.auug.org.au> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:51902 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752177AbdLGEm2 (ORCPT ); Wed, 6 Dec 2017 23:42:28 -0500 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB74e5S7090699 for ; Wed, 6 Dec 2017 23:42:28 -0500 Received: from e14.ny.us.ibm.com (e14.ny.us.ibm.com [129.33.205.204]) by mx0a-001b2d01.pphosted.com with ESMTP id 2epwpq29q7-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 06 Dec 2017 23:42:27 -0500 Received: from localhost by e14.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Dec 2017 23:42:26 -0500 Content-Disposition: inline In-Reply-To: <20171207152521.0036b131@canb.auug.org.au> Sender: linux-next-owner@vger.kernel.org List-ID: To: Stephen Rothwell Cc: Bart Van Assche , "Martin K. Petersen" , Linus Kernel Mailing List , Linux Next Mailing List , Pavel Tikhomirov , Josh Triplett On Thu, Dec 07, 2017 at 03:25:21PM +1100, Stephen Rothwell wrote: > Hi Bart, > > [cc'ing some RCU people ...] > > On Thu, 7 Dec 2017 03:59:30 +0000 Bart Van Assche wrote: > > > > On Thu, 2017-12-07 at 14:57 +1100, Stephen Rothwell wrote: > > > After merging the scsi-mkp tree, today's linux-next build (x86_64 > > > allmodconfig) failed like this: > > > > > > ERROR: "init_rcu_head" [drivers/scsi/scsi_mod.ko] undefined! > > > ERROR: "destroy_rcu_head" [drivers/scsi/scsi_mod.ko] undefined! > > > > > > Caused by commit > > > > > > ac90420f17c9 ("scsi: core: Ensure that the SCSI error handler gets woken up") > > > > > > I have used the scsi-mkp tree from next-20171206 for today. > > > > Does that mean I'm the first one who added RCU code to the SCSI core? > > The only other uses of init_rcu_head() are in drivers/iommu/intel-svm.c > and kernel/irq/irqdesc.c. destroy_rcu_head() appears to not be used > anywhere ... The key point is that Bart appears to be the first to try using them in a module, for which exports are needed. Does the patch below help? Thanx, Paul ------------------------------------------------------------------------ commit cde4691a3a4591e7355295dd62610e3262159002 Author: Paul E. McKenney Date: Wed Dec 6 20:39:38 2017 -0800 rcu: Export init_rcu_head() and destroy_rcu_head() to GPL modules Use of init_rcu_head() and destroy_rcu_head() from modules results in the following build-time error: ERROR: "init_rcu_head" [drivers/scsi/scsi_mod.ko] undefined! ERROR: "destroy_rcu_head" [drivers/scsi/scsi_mod.ko] undefined! This commit therefore adds EXPORT_SYMBOL_GPL() for each to allow them to be used by GPL-licensed kernel modules. Reported-by: Bart Van Assche Reported-by: Stephen Rothwell Signed-off-by: Paul E. McKenney diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 8d591d8411fe..4c4d26e9a67b 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -422,11 +422,13 @@ void init_rcu_head(struct rcu_head *head) { debug_object_init(head, &rcuhead_debug_descr); } +EXPORT_SYMBOL_GPL(init_rcu_head); void destroy_rcu_head(struct rcu_head *head) { debug_object_free(head, &rcuhead_debug_descr); } +EXPORT_SYMBOL_GPL(destroy_rcu_head); static bool rcuhead_is_static_object(void *addr) {