uio: change to use the mutex lock instead of the spin lock

We are hitting a regression with the following commit:

commit a93e7b331568227500186a465fee3c2cb5dffd1f
Author: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Date:   Mon May 14 13:32:23 2018 +1200

    uio: Prevent device destruction while fds are open

The problem is the addition of spin_lock_irqsave in uio_write. This
leads to hitting  uio_write -> copy_from_user -> _copy_from_user ->
might_fault and the logs filling up with sleeping warnings.

I also noticed some uio drivers allocate memory, sleep, grab mutexes
from callouts like open() and release and uio is now doing
spin_lock_irqsave while calling them.

Reported-by: Mike Christie <mchristi@redhat.com>
CC: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Reviewed-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index b4b2ae1..655ade4 100644 (file)
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -433,7 +433,6 @@ static int uio_open(struct inode *inode, struct file *filep)
        struct uio_device *idev;
        struct uio_listener *listener;
        int ret = 0;
-       unsigned long flags;
 
        mutex_lock(&minor_lock);
        idev = idr_find(&uio_idr, iminor(inode));
@@ -460,10 +459,10 @@ static int uio_open(struct inode *inode, struct file *filep)
        listener->event_count = atomic_read(&idev->event);
        filep->private_data = listener;
 
-       spin_lock_irqsave(&idev->info_lock, flags);
+       mutex_lock(&idev->info_lock);
        if (idev->info && idev->info->open)
                ret = idev->info->open(idev->info, inode);
-       spin_unlock_irqrestore(&idev->info_lock, flags);
+       mutex_unlock(&idev->info_lock);
        if (ret)
                goto err_infoopen;
 
@@ -495,12 +494,11 @@ static int uio_release(struct inode *inode, struct file *filep)
        int ret = 0;
        struct uio_listener *listener = filep->private_data;
        struct uio_device *idev = listener->dev;
-       unsigned long flags;
 
-       spin_lock_irqsave(&idev->info_lock, flags);
+       mutex_lock(&idev->info_lock);
        if (idev->info && idev->info->release)
                ret = idev->info->release(idev->info, inode);
-       spin_unlock_irqrestore(&idev->info_lock, flags);
+       mutex_unlock(&idev->info_lock);
 
        module_put(idev->owner);
        kfree(listener);
@@ -513,12 +511,11 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
        struct uio_listener *listener = filep->private_data;
        struct uio_device *idev = listener->dev;
        __poll_t ret = 0;
-       unsigned long flags;
 
-       spin_lock_irqsave(&idev->info_lock, flags);
+       mutex_lock(&idev->info_lock);
        if (!idev->info || !idev->info->irq)
                ret = -EIO;
-       spin_unlock_irqrestore(&idev->info_lock, flags);
+       mutex_unlock(&idev->info_lock);
 
        if (ret)
                return ret;
@@ -537,12 +534,11 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
        DECLARE_WAITQUEUE(wait, current);
        ssize_t retval = 0;
        s32 event_count;
-       unsigned long flags;
 
-       spin_lock_irqsave(&idev->info_lock, flags);
+       mutex_lock(&idev->info_lock);
        if (!idev->info || !idev->info->irq)
                retval = -EIO;
-       spin_unlock_irqrestore(&idev->info_lock, flags);
+       mutex_unlock(&idev->info_lock);
 
        if (retval)
                return retval;
@@ -592,9 +588,8 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
        struct uio_device *idev = listener->dev;
        ssize_t retval;
        s32 irq_on;
-       unsigned long flags;
 
-       spin_lock_irqsave(&idev->info_lock, flags);
+       mutex_lock(&idev->info_lock);
        if (!idev->info || !idev->info->irq) {
                retval = -EIO;
                goto out;
@@ -618,7 +613,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
        retval = idev->info->irqcontrol(idev->info, irq_on);
 
 out:
-       spin_unlock_irqrestore(&idev->info_lock, flags);
+       mutex_unlock(&idev->info_lock);
        return retval ? retval : sizeof(s32);
 }
 
@@ -865,7 +860,7 @@ int __uio_register_device(struct module *owner,
 
        idev->owner = owner;
        idev->info = info;
-       spin_lock_init(&idev->info_lock);
+       mutex_init(&idev->info_lock);
        init_waitqueue_head(&idev->wait);
        atomic_set(&idev->event, 0);
 
@@ -929,7 +924,6 @@ EXPORT_SYMBOL_GPL(__uio_register_device);
 void uio_unregister_device(struct uio_info *info)
 {
        struct uio_device *idev;
-       unsigned long flags;
 
        if (!info || !info->uio_dev)
                return;
@@ -943,9 +937,9 @@ void uio_unregister_device(struct uio_info *info)
        if (info->irq && info->irq != UIO_IRQ_CUSTOM)
                free_irq(info->irq, idev);
 
-       spin_lock_irqsave(&idev->info_lock, flags);
+       mutex_lock(&idev->info_lock);
        idev->info = NULL;
-       spin_unlock_irqrestore(&idev->info_lock, flags);
+       mutex_unlock(&idev->info_lock);
 
        device_unregister(&idev->dev);
 

diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 6c5f207..6f8b68c 100644 (file)
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -75,7 +75,7 @@ struct uio_device {
         struct fasync_struct    *async_queue;
         wait_queue_head_t       wait;
         struct uio_info         *info;
-       spinlock_t              info_lock;
+       struct mutex            info_lock;
         struct kobject          *map_dir;
         struct kobject          *portio_dir;
 };