In previous patch, using return -EBUSY in really_probe() instead WARN_ON()
only. The following is the partial code.
...
atomic_inc(&probe_count);
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
drv->bus->name, __func__, drv->name, dev_name(dev));
if (!list_empty(&dev->devres_head)) {
dev_crit(dev, "Resources present before probing\n");
return -EBUSY;
}
...
When the devres_head is not empty, this code will return -EBUSY to prevent
resource conflict, but it forgot to balance probe_count. We can move the
increasement code below the resource checking.
...
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
drv->bus->name, __func__, drv->name, dev_name(dev));
if (!list_empty(&dev->devres_head)) {
dev_crit(dev, "Resources present before probing\n");
return -EBUSY;
}
atomic_inc(&probe_count);
...
The original code will cause lots motherboard freeze in reboot/shutdown
with systemd message "Reached target Reboot" or "Reached target Shutdown"
with serial8250 platform driver. e.g. AOPEN DE6200. The conflict boot
dmesg below:
Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled
00:03: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 921600) is a 16550A
00:04: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 921600) is a 16550A
00:05: ttyS2 at I/O 0x3e8 (irq = 5, base_baud = 921600) is a 16550A
serial8250: ttyS3 at I/O 0x2e8 (irq = 3, base_baud = 921600) is a 16550A
Reboot/Shutdown will freeze in wait_for_device_probe(), message as
following:
INFQ: task systemd-shutdown: 1 blocked for more than 120 seconds.
Not tainted 5.7.0-rc7-tty-next+ #241
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
message.
Call Trace:
__schedule+0x3d2/0x700
? printk+0x52/0x6e
schedule+0x4f/0xc0
wait_for_device_probe+0xbb/0xl40
? wait_woken+0x80/0x80
device_shutdown+0xl5/0xle0
kernel_power_off+0x35/0x70
__do_sys_reboot+0xla0/0x220
? do_sigtimedwait+0xld0/0x210
? do.writev+0x6a/0xll0
? do.writev+0x6a/0xll0
? sigprocmask+0x6f/Oxa0
__64_sys_reboot+0xle/0x20
do_syscall_64+0x57/0xlb0
Fixes: 7c35e699c88b ("driver core: Print device when resources present in
really_probe()")
Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_ker...@gmail.com>
---
drivers/base/dd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9a1d940342ac..5173b0766a26 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -487,7 +487,6 @@ static int really_probe(struct device *dev, struct
device_driver *drv)
if (ret)
return ret;
- atomic_inc(&probe_count);
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
drv->bus->name, __func__, drv->name, dev_name(dev));
if (!list_empty(&dev->devres_head)) {
@@ -495,6 +494,8 @@ static int really_probe(struct device *dev, struct
device_driver *drv)
return -EBUSY;
}
+ atomic_inc(&probe_count);
+
re_probe:
dev->driver = drv;
--
2.17.1
