In case create_singlethread_workqueue fails, the fix notifies
callers the error to avoid potential NULL pointer dereferences.
Signed-off-by: Kangjie Lu <[email protected]>
---
drivers/usb/host/u132-hcd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
index 934584f0a20a..6d5b532b03f8 100644
--- a/drivers/usb/host/u132-hcd.c
+++ b/drivers/usb/host/u132-hcd.c
@@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
return -ENODEV;
printk(KERN_INFO "driver %s\n", hcd_name);
workqueue = create_singlethread_workqueue("u132");
+ if (unlikely(!workqueue))
+ return -ENOMEM;
retval = platform_driver_register(&u132_platform_driver);
return retval;
}
--
2.17.1
On Thu, Mar 14, 2019 at 02:27:11AM -0500, Kangjie Lu wrote:
> In case create_singlethread_workqueue fails, the fix notifies
> callers the error to avoid potential NULL pointer dereferences.
>
> Signed-off-by: Kangjie Lu <[email protected]>
> ---
> drivers/usb/host/u132-hcd.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
> index 934584f0a20a..6d5b532b03f8 100644
> --- a/drivers/usb/host/u132-hcd.c
> +++ b/drivers/usb/host/u132-hcd.c
> @@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
> return -ENODEV;
> printk(KERN_INFO "driver %s\n", hcd_name);
> workqueue = create_singlethread_workqueue("u132");
> + if (unlikely(!workqueue))
You only ever use unlikely/likely if you can actually measure the
difference with and without it. For stuff like this, it is not needed
at all, and in fact, the compiler and CPU already know this type of
thing, so it is going to be faster without it.
And are you sure you properly unwound from anything that was
created/initialized above these lines?
thanks,
greg k-h
On 3/19/19 8:56 AM, Greg Kroah-Hartman wrote:
> On Thu, Mar 14, 2019 at 02:27:11AM -0500, Kangjie Lu wrote:
>> In case create_singlethread_workqueue fails, the fix notifies
>> callers the error to avoid potential NULL pointer dereferences.
>>
>> Signed-off-by: Kangjie Lu <[email protected]>
>> ---
>> drivers/usb/host/u132-hcd.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
>> index 934584f0a20a..6d5b532b03f8 100644
>> --- a/drivers/usb/host/u132-hcd.c
>> +++ b/drivers/usb/host/u132-hcd.c
>> @@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
>> return -ENODEV;
>> printk(KERN_INFO "driver %s\n", hcd_name);
>> workqueue = create_singlethread_workqueue("u132");
>> + if (unlikely(!workqueue))
> You only ever use unlikely/likely if you can actually measure the
> difference with and without it. For stuff like this, it is not needed
> at all, and in fact, the compiler and CPU already know this type of
> thing, so it is going to be faster without it.
>
> And are you sure you properly unwound from anything that was
> created/initialized above these lines?
I didn't see what resources require release in this
case.
Given the existing error paths for usb_disabled() and
platform_driver_register(), returning -ENOMEM looks
like a consistent error handling. Let me know if it
isn't.
>
> thanks,
>
> greg k-h
In case create_singlethread_workqueue fails, the fix notifies
callers the error to avoid potential NULL pointer dereferences.
Signed-off-by: Kangjie Lu <[email protected]>
---
removed "unlikely"
---
drivers/usb/host/u132-hcd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
index 934584f0a20a..6d5b532b03f8 100644
--- a/drivers/usb/host/u132-hcd.c
+++ b/drivers/usb/host/u132-hcd.c
@@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
return -ENODEV;
printk(KERN_INFO "driver %s\n", hcd_name);
workqueue = create_singlethread_workqueue("u132");
+ if (!workqueue)
+ return -ENOMEM;
retval = platform_driver_register(&u132_platform_driver);
return retval;
}
--
2.17.1
On Tue, Mar 19, 2019 at 12:34:06PM -0500, Kangjie Lu wrote:
> In case create_singlethread_workqueue fails, the fix notifies
> callers the error to avoid potential NULL pointer dereferences.
>
> Signed-off-by: Kangjie Lu <[email protected]>
> ---
> removed "unlikely"
> ---
> drivers/usb/host/u132-hcd.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
> index 934584f0a20a..6d5b532b03f8 100644
> --- a/drivers/usb/host/u132-hcd.c
> +++ b/drivers/usb/host/u132-hcd.c
> @@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
> return -ENODEV;
> printk(KERN_INFO "driver %s\n", hcd_name);
> workqueue = create_singlethread_workqueue("u132");
> + if (!workqueue)
> + return -ENOMEM;
> retval = platform_driver_register(&u132_platform_driver);
> return retval;
if platform_driver_register() fails, shouldn't you clean up the
workqueue? That can be a separate patch, that's not your fault here :)
thanks,
greg k-h
Please change the patch version in subject while sending patch.
On 3/26/2019 10:11 AM, Greg Kroah-Hartman wrote:
> On Tue, Mar 19, 2019 at 12:34:06PM -0500, Kangjie Lu wrote:
>> In case create_singlethread_workqueue fails, the fix notifies
>> callers the error to avoid potential NULL pointer dereferences.
>>
>> Signed-off-by: Kangjie Lu <[email protected]>
Reviewed-by: Mukesh Ojha <[email protected]>
-Mukesh
>> ---
>> removed "unlikely"
>> ---
>> drivers/usb/host/u132-hcd.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/usb/host/u132-hcd.c b/drivers/usb/host/u132-hcd.c
>> index 934584f0a20a..6d5b532b03f8 100644
>> --- a/drivers/usb/host/u132-hcd.c
>> +++ b/drivers/usb/host/u132-hcd.c
>> @@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
>> return -ENODEV;
>> printk(KERN_INFO "driver %s\n", hcd_name);
>> workqueue = create_singlethread_workqueue("u132");
>> + if (!workqueue)
>> + return -ENOMEM;
>> retval = platform_driver_register(&u132_platform_driver);
>> return retval;
> if platform_driver_register() fails, shouldn't you clean up the
> workqueue? That can be a separate patch, that's not your fault here :)
I have taken care of it.
https://lore.kernel.org/patchwork/patch/1054800/
>
> thanks,
>
> greg k-h