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From: Amol Grover <frextrite@gmail.com>
To: Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>,
	linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
	Joel Fernandes <joel@joelfernandes.org>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH] drivers: nvme: target: core: Pass lockdep expression to RCU lists
Date: Fri, 10 Jan 2020 18:53:58 +0530	[thread overview]
Message-ID: <20200110132356.27110-1-frextrite@gmail.com> (raw)

ctrl->subsys->namespaces and subsys->namespaces are traversed with
hlist_for_each_entry_rcu outside an RCU read-side critical section
but under the protection of subsys->lock.

Hence, add the corresponding lockdep expression to the list traversal
primitive to silence false-positive lockdep warnings, and
harden RCU lists.

Add macro for the corresponding lockdep expression to make the code
clean and concise.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 drivers/nvme/target/core.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 28438b833c1b..7caab4ba6a04 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -15,6 +15,9 @@
 
 #include "nvmet.h"
 
+#define subsys_lock_held() \
+	lockdep_is_held(&subsys->lock)
+
 struct workqueue_struct *buffered_io_wq;
 static const struct nvmet_fabrics_ops *nvmet_transports[NVMF_TRTYPE_MAX];
 static DEFINE_IDA(cntlid_ida);
@@ -555,7 +558,8 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
 	} else {
 		struct nvmet_ns *old;
 
-		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link) {
+		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link,
+							subsys_lock_held()) {
 			BUG_ON(ns->nsid == old->nsid);
 			if (ns->nsid < old->nsid)
 				break;
@@ -1172,7 +1176,8 @@ static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,
 
 	ctrl->p2p_client = get_device(req->p2p_client);
 
-	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link)
+	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
+							subsys_lock_held())
 		nvmet_p2pmem_ns_add_p2p(ctrl, ns);
 }
 
-- 
2.24.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

WARNING: multiple messages have this Message-ID (diff)
From: Amol Grover <frextrite@gmail.com>
To: Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>,
	Amol Grover <frextrite@gmail.com>,
	linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
	Joel Fernandes <joel@joelfernandes.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
Subject: [PATCH] drivers: nvme: target: core: Pass lockdep expression to RCU lists
Date: Fri, 10 Jan 2020 18:53:58 +0530	[thread overview]
Message-ID: <20200110132356.27110-1-frextrite@gmail.com> (raw)

ctrl->subsys->namespaces and subsys->namespaces are traversed with
hlist_for_each_entry_rcu outside an RCU read-side critical section
but under the protection of subsys->lock.

Hence, add the corresponding lockdep expression to the list traversal
primitive to silence false-positive lockdep warnings, and
harden RCU lists.

Add macro for the corresponding lockdep expression to make the code
clean and concise.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 drivers/nvme/target/core.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 28438b833c1b..7caab4ba6a04 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -15,6 +15,9 @@
 
 #include "nvmet.h"
 
+#define subsys_lock_held() \
+	lockdep_is_held(&subsys->lock)
+
 struct workqueue_struct *buffered_io_wq;
 static const struct nvmet_fabrics_ops *nvmet_transports[NVMF_TRTYPE_MAX];
 static DEFINE_IDA(cntlid_ida);
@@ -555,7 +558,8 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
 	} else {
 		struct nvmet_ns *old;
 
-		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link) {
+		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link,
+							subsys_lock_held()) {
 			BUG_ON(ns->nsid == old->nsid);
 			if (ns->nsid < old->nsid)
 				break;
@@ -1172,7 +1176,8 @@ static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,
 
 	ctrl->p2p_client = get_device(req->p2p_client);
 
-	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link)
+	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
+							subsys_lock_held())
 		nvmet_p2pmem_ns_add_p2p(ctrl, ns);
 }
 
-- 
2.24.1


_______________________________________________
linux-nvme mailing list
linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

WARNING: multiple messages have this Message-ID (diff)
From: Amol Grover <frextrite@gmail.com>
To: Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Joel Fernandes <joel@joelfernandes.org>,
	Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Amol Grover <frextrite@gmail.com>
Subject: [PATCH] drivers: nvme: target: core: Pass lockdep expression to RCU lists
Date: Fri, 10 Jan 2020 18:53:58 +0530	[thread overview]
Message-ID: <20200110132356.27110-1-frextrite@gmail.com> (raw)

ctrl->subsys->namespaces and subsys->namespaces are traversed with
hlist_for_each_entry_rcu outside an RCU read-side critical section
but under the protection of subsys->lock.

Hence, add the corresponding lockdep expression to the list traversal
primitive to silence false-positive lockdep warnings, and
harden RCU lists.

Add macro for the corresponding lockdep expression to make the code
clean and concise.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 drivers/nvme/target/core.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 28438b833c1b..7caab4ba6a04 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -15,6 +15,9 @@
 
 #include "nvmet.h"
 
+#define subsys_lock_held() \
+	lockdep_is_held(&subsys->lock)
+
 struct workqueue_struct *buffered_io_wq;
 static const struct nvmet_fabrics_ops *nvmet_transports[NVMF_TRTYPE_MAX];
 static DEFINE_IDA(cntlid_ida);
@@ -555,7 +558,8 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
 	} else {
 		struct nvmet_ns *old;
 
-		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link) {
+		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link,
+							subsys_lock_held()) {
 			BUG_ON(ns->nsid == old->nsid);
 			if (ns->nsid < old->nsid)
 				break;
@@ -1172,7 +1176,8 @@ static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,
 
 	ctrl->p2p_client = get_device(req->p2p_client);
 
-	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link)
+	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
+							subsys_lock_held())
 		nvmet_p2pmem_ns_add_p2p(ctrl, ns);
 }
 
-- 
2.24.1


             reply	other threads:[~2020-01-10 13:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 13:23 Amol Grover [this message]
2020-01-10 13:23 ` [PATCH] drivers: nvme: target: core: Pass lockdep expression to RCU lists Amol Grover
2020-01-10 13:23 ` Amol Grover
2020-01-10 15:47 ` [Linux-kernel-mentees] " Joel Fernandes
2020-01-10 15:47   ` Joel Fernandes
2020-01-10 15:47   ` Joel Fernandes
2020-01-10 16:31 ` [Linux-kernel-mentees] " Keith Busch
2020-01-10 16:31   ` Keith Busch
2020-01-10 16:31   ` Keith Busch
2020-01-10 17:10   ` [Linux-kernel-mentees] " Amol Grover
2020-01-10 17:10     ` Amol Grover
2020-01-10 17:10     ` Amol Grover

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