On runtime resume, pci_dev_wait() is called:
pci_pm_runtime_resume()
pci_pm_bridge_power_up_actions()
pci_bridge_wait_for_secondary_bus()
pci_dev_wait()
While a device is runtime suspended along with its PCIe hierarchy, the
device could get disconnected. In such case, the link will not come up
no matter how log pci_dev_wait() waits for it.
Besides the above mentioned case, there could be other ways to get the
device disconnected while pci_dev_wait() is waiting for the link to
come up.
Make pci_dev_wait() to exit if the device is already disconnected to
avoid unnecessary delay. As disconnected device is not really even a
failure in the same sense as link failing to come up for whatever
reason, return 0 instead of errno.
Also make sure compiler does not become too clever with
dev->error_state and use READ_ONCE() to force a fetch for the
up-to-date value.
Reported-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
drivers/pci/pci.c | 5 +++++
drivers/pci/pci.h | 4 +++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d8f11a078924..ec9bf6c90312 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1250,6 +1250,11 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
for (;;) {
u32 id;
+ if (pci_dev_is_disconnected(dev)) {
+ pci_dbg(dev, "disconnected; not waiting\n");
+ return 0;
+ }
+
pci_read_config_dword(dev, PCI_COMMAND, &id);
if (!PCI_POSSIBLE_ERROR(id))
break;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 2336a8d1edab..563a275dff67 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -4,6 +4,8 @@
#include <linux/pci.h>
+#include <asm/rwonce.h>
+
/* Number of possible devfns: 0.0 to 1f.7 inclusive */
#define MAX_NR_DEVFNS 256
@@ -370,7 +372,7 @@ static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
static inline bool pci_dev_is_disconnected(const struct pci_dev *dev)
{
- return dev->error_state == pci_channel_io_perm_failure;
+ return READ_ONCE(dev->error_state) == pci_channel_io_perm_failure;
}
/* pci_dev priv_flags */
--
2.39.2
