Re: [PATCH 7/9] x86/pci: Pass lockdep condition to pcm_mmcfg_list iterator (v1)
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2019-07-15 20:02:47
Also in:
linux-acpi, linux-pci, linux-pm, lkml, netdev, rcu
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) <redacted>
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.
quoted hunk ↗ jump to hunk
--- 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