Re: [PATCH 5/9] driver/core: Convert to use built-in RCU list checking (v1)

From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Borislav Petkov <bp@alien8.de>,
	c0d1n61at3@gmail.com, "David S. Miller" <davem@davemloft.net>,
	edumazet@google.com, Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Josh Triplett <josh@joshtriplett.org>,
	keescook@chromium.org, kernel-hardening@lists.openwall.com,
	kernel-team@android.com, Lai Jiangshan <jiangshanlai@gmail.com>,
	Len Brown <lenb@kernel.org>,
	linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-pm@vger.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	neilb@suse.com, netdev@vger.kernel.org,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	peterz@infradead.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
	rcu@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Tejun Heo <tj@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
	will@kernel.org,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>
Subject: Re: [PATCH 5/9] driver/core: Convert to use built-in RCU list checking (v1)
Date: Tue, 16 Jul 2019 11:40:25 -0700	[thread overview]
Message-ID: <20190716184025.GG14271@linux.ibm.com> (raw)
In-Reply-To: <20190715143705.117908-6-joel@joelfernandes.org>

On Mon, Jul 15, 2019 at 10:37:01AM -0400, Joel Fernandes (Google) wrote:
> list_for_each_entry_rcu has built-in RCU and lock checking. Make use of
> it in driver core.
> 
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>

This one looks ready.

							Thanx, Paul

> ---
>  drivers/base/base.h          |  1 +
>  drivers/base/core.c          | 10 ++++++++++
>  drivers/base/power/runtime.c | 15 ++++++++++-----
>  3 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index b405436ee28e..0d32544b6f91 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -165,6 +165,7 @@ static inline int devtmpfs_init(void) { return 0; }
>  /* Device links support */
>  extern int device_links_read_lock(void);
>  extern void device_links_read_unlock(int idx);
> +extern int device_links_read_lock_held(void);
>  extern int device_links_check_suppliers(struct device *dev);
>  extern void device_links_driver_bound(struct device *dev);
>  extern void device_links_driver_cleanup(struct device *dev);
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index da84a73f2ba6..85e82f38717f 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -68,6 +68,11 @@ void device_links_read_unlock(int idx)
>  {
>  	srcu_read_unlock(&device_links_srcu, idx);
>  }
> +
> +int device_links_read_lock_held(void)
> +{
> +	return srcu_read_lock_held(&device_links_srcu);
> +}
>  #else /* !CONFIG_SRCU */
>  static DECLARE_RWSEM(device_links_lock);
>  
> @@ -91,6 +96,11 @@ void device_links_read_unlock(int not_used)
>  {
>  	up_read(&device_links_lock);
>  }
> +
> +int device_links_read_lock_held(void)
> +{
> +	return lock_is_held(&device_links_lock);
> +}
>  #endif /* !CONFIG_SRCU */
>  
>  /**
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 952a1e7057c7..7a10e8379a70 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -287,7 +287,8 @@ static int rpm_get_suppliers(struct device *dev)
>  {
>  	struct device_link *link;
>  
> -	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
> +	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> +				device_links_read_lock_held()) {
>  		int retval;
>  
>  		if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
> @@ -309,7 +310,8 @@ static void rpm_put_suppliers(struct device *dev)
>  {
>  	struct device_link *link;
>  
> -	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
> +	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> +				device_links_read_lock_held()) {
>  		if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
>  			continue;
>  
> @@ -1640,7 +1642,8 @@ void pm_runtime_clean_up_links(struct device *dev)
>  
>  	idx = device_links_read_lock();
>  
> -	list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
> +	list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
> +				device_links_read_lock_held()) {
>  		if (link->flags & DL_FLAG_STATELESS)
>  			continue;
>  
> @@ -1662,7 +1665,8 @@ void pm_runtime_get_suppliers(struct device *dev)
>  
>  	idx = device_links_read_lock();
>  
> -	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
> +	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> +				device_links_read_lock_held())
>  		if (link->flags & DL_FLAG_PM_RUNTIME) {
>  			link->supplier_preactivated = true;
>  			refcount_inc(&link->rpm_active);
> @@ -1683,7 +1687,8 @@ void pm_runtime_put_suppliers(struct device *dev)
>  
>  	idx = device_links_read_lock();
>  
> -	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
> +	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> +				device_links_read_lock_held())
>  		if (link->supplier_preactivated) {
>  			link->supplier_preactivated = false;
>  			if (refcount_dec_not_one(&link->rpm_active))
> -- 
> 2.22.0.510.g264f2c817a-goog
> 