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Subject[PATCH] PCI: Add a mutex to protect the global list pci_domain_busn_res_list
Date
There has been an effort to make the pci-hyperv driver support
async-probing to reduce the boot time. With async-probing, multiple
kernel threads can be running hv_pci_probe() -> create_root_hv_pci_bus() ->
pci_scan_root_bus_bridge() -> pci_bus_insert_busn_res() at the same time to
update the global list, causing list corruption.

Add a mutex to protect the list.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
drivers/pci/probe.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e19b79821dd6..1327fd820b24 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -37,6 +37,7 @@ LIST_HEAD(pci_root_buses);
EXPORT_SYMBOL(pci_root_buses);

static LIST_HEAD(pci_domain_busn_res_list);
+static DEFINE_MUTEX(pci_domain_busn_res_list_lock);

struct pci_domain_busn_res {
struct list_head list;
@@ -47,14 +48,22 @@ struct pci_domain_busn_res {
static struct resource *get_pci_domain_busn_res(int domain_nr)
{
struct pci_domain_busn_res *r;
+ struct resource *ret;

- list_for_each_entry(r, &pci_domain_busn_res_list, list)
- if (r->domain_nr == domain_nr)
- return &r->res;
+ mutex_lock(&pci_domain_busn_res_list_lock);
+
+ list_for_each_entry(r, &pci_domain_busn_res_list, list) {
+ if (r->domain_nr == domain_nr) {
+ ret = &r->res;
+ goto out;
+ }
+ }

r = kzalloc(sizeof(*r), GFP_KERNEL);
- if (!r)
- return NULL;
+ if (!r) {
+ ret = NULL;
+ goto out;
+ }

r->domain_nr = domain_nr;
r->res.start = 0;
@@ -62,8 +71,10 @@ static struct resource *get_pci_domain_busn_res(int domain_nr)
r->res.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED;

list_add_tail(&r->list, &pci_domain_busn_res_list);
-
- return &r->res;
+ ret = &r->res;
+out:
+ mutex_unlock(&pci_domain_busn_res_list_lock);
+ return ret;
}

/*
--
2.25.1

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