diff options
author | Yijing Wang <wangyijing@huawei.com> | 2015-07-17 17:16:31 +0800 |
---|---|---|
committer | Bjorn Helgaas <bhelgaas@google.com> | 2015-07-30 15:49:10 -0500 |
commit | 67546762978f523749eac157903e0b01c18e083a (patch) | |
tree | 646a5a8749dae0c3192d9db23dc4eb1f63f90f75 /drivers/pci | |
parent | ac10836b681289f7e430e52b106a209bbdcaa75e (diff) | |
download | linux-67546762978f523749eac157903e0b01c18e083a.tar.bz2 |
PCI: Protect pci_bus->slots with pci_slot_mutex, not pci_bus_sem
Rajat Jain reported a deadlock when PCIe hot-add and AER recovery happen at
the same time:
thread 1:
pciehp_enable_slot
pciehp_configure_device
pci_bus_add_devices
pci_bus_add_device
device_attach
device_lock(dev) # acquire device lock
...
pciehp_probe
init_slot
pci_hp_register
pci_create_slot
down_write(pci_bus_sem) # deadlock here
thread 2:
aer_isr_one_error
aer_process_err_device
do_recovery
broadcast_error_message(..., report_error_detected)
pci_walk_bus(..., cb=report_error_detected, ...)
down_read(&pci_bus_sem) # acquire pci_bus_sem
report_error_detected(dev) # cb()
device_lock(dev) # deadlock here
Previously, the bus->devices and bus->slots list were protected by
pci_bus_sem. In pci_create_slot(), we held it for writing so we could
add to the bus->slots list.
Add a new local pci_slot_mutex to protect bus->slots. Hold pci_bus_sem for
reading while searching the bus->devices list.
[bhelgaas: changelog]
Link: http://lkml.kernel.org/r/CAA93t1qpPqbih+UB0McA_d_+2rVaNkXsinAUxYzK9+JXSS+L-g@mail.gmail.com
Reported-by: Rajat Jain <rajatja@google.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/pci')
-rw-r--r-- | drivers/pci/slot.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c index 396c200b9ddb..4bd3fce93fa4 100644 --- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -14,6 +14,7 @@ struct kset *pci_slots_kset; EXPORT_SYMBOL_GPL(pci_slots_kset); +static DEFINE_MUTEX(pci_slot_mutex); static ssize_t pci_slot_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) @@ -106,9 +107,11 @@ static void pci_slot_release(struct kobject *kobj) dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n", slot->number, pci_slot_name(slot)); + down_read(&pci_bus_sem); list_for_each_entry(dev, &slot->bus->devices, bus_list) if (PCI_SLOT(dev->devfn) == slot->number) dev->slot = NULL; + up_read(&pci_bus_sem); list_del(&slot->list); @@ -194,9 +197,8 @@ static int rename_slot(struct pci_slot *slot, const char *name) static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr) { struct pci_slot *slot; - /* - * We already hold pci_bus_sem so don't worry - */ + + /* We already hold pci_slot_mutex */ list_for_each_entry(slot, &parent->slots, list) if (slot->number == slot_nr) { kobject_get(&slot->kobj); @@ -253,7 +255,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr, int err = 0; char *slot_name = NULL; - down_write(&pci_bus_sem); + mutex_lock(&pci_slot_mutex); if (slot_nr == -1) goto placeholder; @@ -301,16 +303,18 @@ placeholder: INIT_LIST_HEAD(&slot->list); list_add(&slot->list, &parent->slots); + down_read(&pci_bus_sem); list_for_each_entry(dev, &parent->devices, bus_list) if (PCI_SLOT(dev->devfn) == slot_nr) dev->slot = slot; + up_read(&pci_bus_sem); dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n", slot_nr, pci_slot_name(slot)); out: kfree(slot_name); - up_write(&pci_bus_sem); + mutex_unlock(&pci_slot_mutex); return slot; err: kfree(slot); @@ -332,9 +336,9 @@ void pci_destroy_slot(struct pci_slot *slot) dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n", slot->number, atomic_read(&slot->kobj.kref.refcount) - 1); - down_write(&pci_bus_sem); + mutex_lock(&pci_slot_mutex); kobject_put(&slot->kobj); - up_write(&pci_bus_sem); + mutex_unlock(&pci_slot_mutex); } EXPORT_SYMBOL_GPL(pci_destroy_slot); |