On Mon, Jul 15, 2019 at 03:02:35PM -0500, Bjorn Helgaas wrote:
> 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@xxxxxxxxxxxxxxxxx>
>
> Ingo takes care of most patches to this file, but FWIW,
>
> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Thanks.
> 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.
Updated below is the patch with the nits corrected:
---8<-----------------------
>From 73fab09d7e33ca2110c24215f8ed428c12625dbe Mon Sep 17 00:00:00 2001
From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Date: Sat, 1 Jun 2019 15:05:49 -0400
Subject: [PATCH] x86/PCI: Pass lockdep condition to pcm_mmcfg_list iterator
(v1)
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().
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
arch/x86/pci/mmconfig-shared.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 7389db538c30..9e3250ec5a37 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 +55,8 @@ 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 +120,8 @@ 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
