From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:45443 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934095AbcIVNfW (ORCPT ); Thu, 22 Sep 2016 09:35:22 -0400 Subject: Patch "IB/hfi1,IB/qib: Fix qp_stats sleep with rcu read lock held" has been added to the 4.7-stable tree To: mike.marciniszyn@intel.com, dledford@redhat.com, gregkh@linuxfoundation.org, ira.weiny@intel.com, leonro@mellanox.com Cc: , From: Date: Thu, 22 Sep 2016 15:34:38 +0200 Message-ID: <1474551278899@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled IB/hfi1,IB/qib: Fix qp_stats sleep with rcu read lock held to the 4.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ib-hfi1-ib-qib-fix-qp_stats-sleep-with-rcu-read-lock-held.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From c62fb260a86dde3df5b2905432caa0e9f6898434 Mon Sep 17 00:00:00 2001 From: Mike Marciniszyn Date: Fri, 12 Aug 2016 11:17:37 -0400 Subject: IB/hfi1,IB/qib: Fix qp_stats sleep with rcu read lock held From: Mike Marciniszyn commit c62fb260a86dde3df5b2905432caa0e9f6898434 upstream. The qp init function does a kzalloc() while holding the RCU lock that encounters the following warning with a debug kernel when a cat of the qp_stats is done: [ 231.723948] rcu_scheduler_active = 1, debug_locks = 0 [ 231.731939] 3 locks held by cat/11355: [ 231.736492] #0: (debugfs_srcu){......}, at: [] debugfs_use_file_start+0x5/0x90 [ 231.746955] #1: (&p->lock){+.+.+.}, at: [] seq_read+0x4c/0x3c0 [ 231.755873] #2: (rcu_read_lock){......}, at: [] _qp_stats_seq_start+0x5/0xd0 [hfi1] [ 231.766862] The init functions do an implicit next which requires the rcu read lock before the kzalloc(). Fix for both drivers is to change the scope of the init function to only do the allocation and the initialization of the just allocated iter. The implict next is moved back into the respective start functions to fix the issue. Signed-off-by: Ira Weiny Signed-off-by: Mike Marciniszyn Reviewed-by: Leon Romanovsky Signed-off-by: Doug Ledford Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/hw/hfi1/debugfs.c | 14 +++++++++----- drivers/infiniband/hw/hfi1/qp.c | 4 ---- drivers/infiniband/hw/qib/qib_debugfs.c | 12 +++++++++--- drivers/infiniband/hw/qib/qib_qp.c | 4 ---- 4 files changed, 18 insertions(+), 16 deletions(-) --- a/drivers/infiniband/hw/hfi1/debugfs.c +++ b/drivers/infiniband/hw/hfi1/debugfs.c @@ -223,28 +223,32 @@ DEBUGFS_SEQ_FILE_OPEN(ctx_stats) DEBUGFS_FILE_OPS(ctx_stats); static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos) -__acquires(RCU) + __acquires(RCU) { struct qp_iter *iter; loff_t n = *pos; - rcu_read_lock(); iter = qp_iter_init(s->private); + + /* stop calls rcu_read_unlock */ + rcu_read_lock(); + if (!iter) return NULL; - while (n--) { + do { if (qp_iter_next(iter)) { kfree(iter); return NULL; } - } + } while (n--); return iter; } static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr, loff_t *pos) + __must_hold(RCU) { struct qp_iter *iter = iter_ptr; @@ -259,7 +263,7 @@ static void *_qp_stats_seq_next(struct s } static void _qp_stats_seq_stop(struct seq_file *s, void *iter_ptr) -__releases(RCU) + __releases(RCU) { rcu_read_unlock(); } --- a/drivers/infiniband/hw/hfi1/qp.c +++ b/drivers/infiniband/hw/hfi1/qp.c @@ -595,10 +595,6 @@ struct qp_iter *qp_iter_init(struct hfi1 iter->dev = dev; iter->specials = dev->rdi.ibdev.phys_port_cnt * 2; - if (qp_iter_next(iter)) { - kfree(iter); - return NULL; - } return iter; } --- a/drivers/infiniband/hw/qib/qib_debugfs.c +++ b/drivers/infiniband/hw/qib/qib_debugfs.c @@ -189,27 +189,32 @@ static int _ctx_stats_seq_show(struct se DEBUGFS_FILE(ctx_stats) static void *_qp_stats_seq_start(struct seq_file *s, loff_t *pos) + __acquires(RCU) { struct qib_qp_iter *iter; loff_t n = *pos; - rcu_read_lock(); iter = qib_qp_iter_init(s->private); + + /* stop calls rcu_read_unlock */ + rcu_read_lock(); + if (!iter) return NULL; - while (n--) { + do { if (qib_qp_iter_next(iter)) { kfree(iter); return NULL; } - } + } while (n--); return iter; } static void *_qp_stats_seq_next(struct seq_file *s, void *iter_ptr, loff_t *pos) + __must_hold(RCU) { struct qib_qp_iter *iter = iter_ptr; @@ -224,6 +229,7 @@ static void *_qp_stats_seq_next(struct s } static void _qp_stats_seq_stop(struct seq_file *s, void *iter_ptr) + __releases(RCU) { rcu_read_unlock(); } --- a/drivers/infiniband/hw/qib/qib_qp.c +++ b/drivers/infiniband/hw/qib/qib_qp.c @@ -530,10 +530,6 @@ struct qib_qp_iter *qib_qp_iter_init(str return NULL; iter->dev = dev; - if (qib_qp_iter_next(iter)) { - kfree(iter); - return NULL; - } return iter; } Patches currently in stable-queue which might be from mike.marciniszyn@intel.com are queue-4.7/ib-hfi1-ib-qib-fix-qp_stats-sleep-with-rcu-read-lock-held.patch