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From: Bjorn Helgaas <helgaas@kernel.org>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Borislav Petkov <bp@alien8.de>,
	c0d1n61at3@gmail.com, "David S. Miller" <davem@davemloft.net>,
	edumazet@google.com,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	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>,
	"Paul E. McKenney" <paulmck@linux.ibm.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 7/9] x86/pci: Pass lockdep condition to pcm_mmcfg_list iterator (v1)
Date: Mon, 15 Jul 2019 15:02:35 -0500
Message-ID: <20190715200235.GG46935@google.com> (raw)
In-Reply-To: <20190715143705.117908-8-joel@joelfernandes.org>

On Mon, Jul 15, 2019 at 10:37:03AM -0400, Joel Fernandes (Google) wrote:
> The pcm_mmcfg_list is traversed with list_for_each_entry_rcu without a
> reader-lock held, because the pci_mmcfg_lock is already held. Make this
> known to the list macro so that it fixes new lockdep warnings that
> trigger due to lockdep checks added to list_for_each_entry_rcu().
> 
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>

Ingo takes care of most patches to this file, but FWIW,

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

I would personally prefer if you capitalized the subject to match the
"x86/PCI:" convention that's used fairly consistently in
arch/x86/pci/.

Also, I didn't apply this to be sure, but it looks like this might
make a line or two wider than 80 columns, which I would rewrap if I
were applying this.

> ---
>  arch/x86/pci/mmconfig-shared.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
> index 7389db538c30..6fa42e9c4e6f 100644
> --- a/arch/x86/pci/mmconfig-shared.c
> +++ b/arch/x86/pci/mmconfig-shared.c
> @@ -29,6 +29,7 @@
>  static bool pci_mmcfg_running_state;
>  static bool pci_mmcfg_arch_init_failed;
>  static DEFINE_MUTEX(pci_mmcfg_lock);
> +#define pci_mmcfg_lock_held() lock_is_held(&(pci_mmcfg_lock).dep_map)
>  
>  LIST_HEAD(pci_mmcfg_list);
>  
> @@ -54,7 +55,7 @@ static void list_add_sorted(struct pci_mmcfg_region *new)
>  	struct pci_mmcfg_region *cfg;
>  
>  	/* keep list sorted by segment and starting bus number */
> -	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list) {
> +	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list, pci_mmcfg_lock_held()) {
>  		if (cfg->segment > new->segment ||
>  		    (cfg->segment == new->segment &&
>  		     cfg->start_bus >= new->start_bus)) {
> @@ -118,7 +119,7 @@ struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus)
>  {
>  	struct pci_mmcfg_region *cfg;
>  
> -	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list)
> +	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list, pci_mmcfg_lock_held())
>  		if (cfg->segment == segment &&
>  		    cfg->start_bus <= bus && bus <= cfg->end_bus)
>  			return cfg;
> -- 
> 2.22.0.510.g264f2c817a-goog
> 

  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15 14:36 [PATCH 0/9] Harden list_for_each_entry_rcu() and family Joel Fernandes (Google)
2019-07-15 14:36 ` [PATCH 1/9] rcu/update: Remove useless check for debug_locks (v1) Joel Fernandes (Google)
2019-07-15 14:36 ` [PATCH 2/9] rcu: Add support for consolidated-RCU reader checking (v3) Joel Fernandes (Google)
2019-07-16 18:38   ` Paul E. McKenney
2019-07-16 18:46     ` Joel Fernandes
2019-07-16 18:53       ` Paul E. McKenney
2019-07-16 22:02         ` Joel Fernandes
2019-07-17  0:07           ` Paul E. McKenney
2019-07-15 14:36 ` [PATCH 3/9] rcu/sync: Remove custom check for reader-section (v2) Joel Fernandes (Google)
2019-07-16 18:39   ` Paul E. McKenney
2019-07-15 14:37 ` [PATCH 4/9] ipv4: add lockdep condition to fix for_each_entry (v1) Joel Fernandes (Google)
2019-07-16 18:39   ` Paul E. McKenney
2019-07-16 21:12     ` David Miller
2019-07-15 14:37 ` [PATCH 5/9] driver/core: Convert to use built-in RCU list checking (v1) Joel Fernandes (Google)
2019-07-16 18:40   ` Paul E. McKenney
2019-07-15 14:37 ` [PATCH 6/9] workqueue: Convert for_each_wq to use built-in list check (v2) Joel Fernandes (Google)
2019-07-16 18:41   ` Paul E. McKenney
2019-07-15 14:37 ` [PATCH 7/9] x86/pci: Pass lockdep condition to pcm_mmcfg_list iterator (v1) Joel Fernandes (Google)
2019-07-15 20:02   ` Bjorn Helgaas [this message]
2019-07-16  4:03     ` Joel Fernandes
2019-07-16 18:42       ` Paul E. McKenney
2019-07-15 14:37 ` [PATCH 8/9] acpi: Use built-in RCU list checking for acpi_ioremaps list (v1) Joel Fernandes (Google)
2019-07-15 21:44   ` Rafael J. Wysocki
2019-07-16 18:43   ` Paul E. McKenney
2019-07-15 14:37 ` [PATCH 9/9] doc: Update documentation about list_for_each_entry_rcu (v1) Joel Fernandes (Google)
2019-07-16 18:46 ` [PATCH 0/9] Harden list_for_each_entry_rcu() and family Paul E. McKenney

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