From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753694AbeDTSI6 (ORCPT ); Fri, 20 Apr 2018 14:08:58 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:42744 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753576AbeDTSI4 (ORCPT ); Fri, 20 Apr 2018 14:08:56 -0400 Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig102.frc2.facebook.com To: CC: , Song Liu , Steven Rostedt , Ingo Molnar , Howard McLauchlan , Josef Bacik , Srikar Dronamraju , Miklos Szeredi Smtp-Origin-Cluster: frc2c02 Subject: [PATCH v4] tracing: remove igrab() iput() call from uprobes.c Date: Fri, 20 Apr 2018 11:08:47 -0700 Message-ID: <20180420180847.418760-1-songliubraving@fb.com> X-Mailer: git-send-email 2.9.5 X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-20_08:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Caller of uprobe_register is required to keep the inode and containing mount point referenced. There was misuse of igrab() in uprobes.c and trace_uprobe.c. This is because igrab() will not prevent umount of the containing mount point. To fix this, we added path to struct trace_uprobe, which keeps the inode and containing mount reference. For uprobes.c sisde, igrab() is not necessary. So we removed it and added comments on requirements to callers of uprobe_register(). Link: http://lkml.kernel.org/r/CAELBmZB2XX=qEOLAdvGG4cPx4GEntcSnWQquJLUK1ongRj35cA@mail.gmail.com Cc: Steven Rostedt Cc: Ingo Molnar Cc: Howard McLauchlan Cc: Josef Bacik Cc: Srikar Dronamraju Cc: Miklos Szeredi Signed-off-by: Song Liu --- kernel/events/uprobes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index ce6848e..20486bb 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -491,7 +491,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) if (!uprobe) return NULL; - uprobe->inode = igrab(inode); uprobe->offset = offset; init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->consumer_rwsem); @@ -502,7 +501,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) if (cur_uprobe) { kfree(uprobe); uprobe = cur_uprobe; - iput(inode); } return uprobe; @@ -701,7 +699,6 @@ static void delete_uprobe(struct uprobe *uprobe) rb_erase(&uprobe->rb_node, &uprobes_tree); spin_unlock(&uprobes_treelock); RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ - iput(uprobe->inode); put_uprobe(uprobe); } @@ -873,7 +870,8 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u * tuple). Creation refcount stops uprobe_unregister from freeing the * @uprobe even before the register operation is complete. Creation * refcount is released when the last @uc for the @uprobe - * unregisters. + * unregisters. Caller of uprobe_register() is required to keep @inode + * (and the containing mount) referenced. * * Return errno if it cannot successully install probes * else return 0 (success) -- 2.9.5