There is an issue in the error path, which cpci_thread may remain NULL.
Calling kthread_stop(cpci_thread) will trigger a BUG().
It is better to check whether the thread is really created and started
before stop it.
[ 1.292859] BUG: kernel NULL pointer dereference, address: 0000000000000028
[ 1.293252] #PF: supervisor write access in kernel mode
[ 1.293533] #PF: error_code(0x0002) - not-present page
[ 1.295163] RIP: 0010:kthread_stop+0x22/0x170
[ 1.300491] Call Trace:
[ 1.300628] cpci_hp_unregister_controller+0xf6/0x130
[ 1.300906] zt5550_hc_init_one+0x27a/0x27f [cpcihp_zt5550]
Signed-off-by: Tong Zhang <ztong0001@xxxxxxxxx>
---
drivers/pci/hotplug/cpci_hotplug_core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/hotplug/cpci_hotplug_core.c b/drivers/pci/hotplug/cpci_hotplug_core.c
index d0559d2faf50..b44da397d631 100644
--- a/drivers/pci/hotplug/cpci_hotplug_core.c
+++ b/drivers/pci/hotplug/cpci_hotplug_core.c
@@ -47,7 +47,7 @@ static atomic_t extracting;
int cpci_debug;
static struct cpci_hp_controller *controller;
static struct task_struct *cpci_thread;
-static int thread_finished;
+static int thread_started;
static int enable_slot(struct hotplug_slot *slot);
static int disable_slot(struct hotplug_slot *slot);
@@ -447,7 +447,7 @@ event_thread(void *data)
msleep(500);
} else if (rc < 0) {
dbg("%s - error checking slots", __func__);
- thread_finished = 1;
+ thread_started = 0;
goto out;
}
} while (atomic_read(&extracting) && !kthread_should_stop());
@@ -479,7 +479,7 @@ poll_thread(void *data)
msleep(500);
} else if (rc < 0) {
dbg("%s - error checking slots", __func__);
- thread_finished = 1;
+ thread_started = 0;
goto out;
}
} while (atomic_read(&extracting) && !kthread_should_stop());
@@ -501,7 +501,7 @@ cpci_start_thread(void)
err("Can't start up our thread");
return PTR_ERR(cpci_thread);
}
- thread_finished = 0;
+ thread_started = 1;
return 0;
}
@@ -509,7 +509,7 @@ static void
cpci_stop_thread(void)
{
kthread_stop(cpci_thread);
- thread_finished = 1;
+ thread_started = 0;
}
int
@@ -571,7 +571,7 @@ cpci_hp_unregister_controller(struct cpci_hp_controller *old_controller)
int status = 0;
if (controller) {
- if (!thread_finished)
+ if (thread_started)
cpci_stop_thread();
if (controller->irq)
free_irq(controller->irq, controller->dev_id);
--
2.25.1
