From: Hongtao Zhang <zhanghongtao22@xxxxxxxxxx>
Switch the driver of the SPDK program that is being read and written from the uio_pci_generic driver to the NVMe driver
(Unbind the UIO driver from the device and bind the NVMe driver to the device.) ,the system crashes and restarts.
Bug reproduction: When the SPDK is reading or writing data, run the following command: /opt/spdk/setup.sh reset
The one with a higher probability of occurrence is as follows:
PANIC: "BUG: unable to handle kernel NULL pointer dereference at 0000000000000008"
[exception RIP: _raw_spin_lock_irqsave+30]
RIP: ffffffff836a1cae RSP: ffff8bca9ecc3f20 RFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000246 RCX: 0000000000000017
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 0000000000000000 R8: 000000afb34e50f9 R9: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8bca9ecc3f50
R13: 0000000000000004 R14: 0000000000000004 R15: 0000000000000000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#7 [ffff8bca9ecc3f28] complete at ffffffff82f09bb8
reason:After the driver switchover, the upper-layer program can still access the bar space of the NVMe disk controller and knock the doorbell.
To solve this problem, a reference counting is added to prevent unbind execution before the application is closed or exited.
Signed-off-by: Hongtao Zhang <zhanghongtao22@xxxxxxxxxx>
Reviewed-by: Weifeng Su <suweifeng1@xxxxxxxxxx>
---
drivers/uio/uio.c | 13 +++++++++++++
include/linux/uio_driver.h | 1 +
2 files changed, 14 insertions(+)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 43afbb7c5ab9..cb8ed29a8648 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -31,6 +31,7 @@ static int uio_major;
static struct cdev *uio_cdev;
static DEFINE_IDR(uio_idr);
static const struct file_operations uio_fops;
+static DECLARE_WAIT_QUEUE_HEAD(refc_wait);
/* Protect idr accesses */
static DEFINE_MUTEX(minor_lock);
@@ -501,6 +502,7 @@ static int uio_open(struct inode *inode, struct file *filep)
mutex_unlock(&idev->info_lock);
if (ret)
goto err_infoopen;
+ refcount_inc(&idev->dev_refc);
return 0;
@@ -536,6 +538,9 @@ static int uio_release(struct inode *inode, struct file *filep)
ret = idev->info->release(idev->info, inode);
mutex_unlock(&idev->info_lock);
+ if (refcount_dec_and_test(&idev->dev_refc))
+ wake_up(&refc_wait);
+
module_put(idev->owner);
kfree(listener);
put_device(&idev->dev);
@@ -937,6 +942,7 @@ int __uio_register_device(struct module *owner,
idev->owner = owner;
idev->info = info;
+ refcount_set(&idev->dev_refc, 0);
mutex_init(&idev->info_lock);
init_waitqueue_head(&idev->wait);
atomic_set(&idev->event, 0);
@@ -1045,6 +1051,7 @@ void uio_unregister_device(struct uio_info *info)
{
struct uio_device *idev;
unsigned long minor;
+ unsigned int dref_count;
if (!info || !info->uio_dev)
return;
@@ -1052,6 +1059,12 @@ void uio_unregister_device(struct uio_info *info)
idev = info->uio_dev;
minor = idev->minor;
+ dref_count = refcount_read(&idev->dev_refc);
+ if (dref_count > 0) {
+ dev_err(&idev->dev, "The device is in use, please close the file descriptor or kill the occupied process\n");
+ wait_event(refc_wait, !refcount_read(&idev->dev_refc));
+ }
+
mutex_lock(&idev->info_lock);
uio_dev_del_attributes(idev);
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 47c5962b876b..28301dcc4d31 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -77,6 +77,7 @@ struct uio_device {
struct mutex info_lock;
struct kobject *map_dir;
struct kobject *portio_dir;
+ refcount_t dev_refc;
};
/**
--
2.27.0
