From: Joel Fernandes <joel@joelfernandes.org>
To: Amol Grover <frextrite@gmail.com>
Cc: Sagi Grimberg <sagi@grimberg.me>,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-kernel-mentees@lists.linuxfoundation.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [Linux-kernel-mentees] [PATCH] drivers: nvme: target: core: Pass lockdep expression to RCU lists
Date: Fri, 10 Jan 2020 10:47:22 -0500 [thread overview]
Message-ID: <20200110154722.GA128013@google.com> (raw)
In-Reply-To: <20200110132356.27110-1-frextrite@gmail.com>
On Fri, Jan 10, 2020 at 06:53:58PM +0530, Amol Grover wrote:
> 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.
Amol, thanks. Could you fix this checkpatch warnings? hint: Use --fix-inplace
CHECK: Alignment should match open parenthesis
#50: FILE: drivers/nvme/target/core.c:562:
+ list_for_each_entry_rcu(old, &subsys->namespaces, dev_link,
+ subsys_lock_held()) {
CHECK: Alignment should match open parenthesis
#60: FILE: drivers/nvme/target/core.c:1180:
+ list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
+ subsys_lock_held())
Otherwise,
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
thanks,
- Joel
>
> 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
>
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next prev parent reply other threads:[~2020-01-10 15:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 13:23 [Linux-kernel-mentees] [PATCH] drivers: nvme: target: core: Pass lockdep expression to RCU lists Amol Grover
2020-01-10 15:47 ` Joel Fernandes [this message]
2020-01-10 16:31 ` Keith Busch
2020-01-10 17:10 ` Amol Grover
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