linux-kernel - Re: [External] : Re: [PATCH v2 3/3] staging: rtl8723bs: add IS_ERR() check for kthread

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Message-ID: <089f7856-558f-4cb9-b56b-3aac40f751cf@oracle.com>
Date: Thu, 8 Jan 2026 22:36:35 -0800
From: samasth.norway.ananda@...cle.com
To: Greg KH <gregkh@...uxfoundation.org>
Cc: dan.carpenter@...aro.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [External] : Re: [PATCH v2 3/3] staging: rtl8723bs: add IS_ERR()
 check for kthread_run()



On 1/8/26 8:50 PM, Greg KH wrote:
> On Thu, Jan 08, 2026 at 10:16:11AM -0800, Samasth Norway Ananda wrote:
>> kthread_run() returns an ERR_PTR on failure, not NULL. Without this
>> check, rtl8723b_stop_thread() would later check "if
>> (xmitpriv->SdioXmitThread)" which evaluates to true for error pointers,
>> potentially causing issues when trying to complete or wait on an invalid
>> thread. Set the pointer to NULL on failure to prevent later code from
>> attempting to use an invalid thread pointer.
>>
>> Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@...cle.com>
>> ---
>>   drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c b/drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c
>> index 56ceedd5a26a..27d490204fcc 100644
>> --- a/drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c
>> +++ b/drivers/staging/rtl8723bs/hal/rtl8723b_hal_init.c
>> @@ -2922,6 +2922,8 @@ void rtl8723b_start_thread(struct adapter *padapter)
>>   	struct xmit_priv *xmitpriv = &padapter->xmitpriv;
>>   
>>   	xmitpriv->SdioXmitThread = kthread_run(rtl8723bs_xmit_thread, padapter, "RTWHALXT");
>> +	if (IS_ERR(xmitpriv->SdioXmitThread))
>> +		xmitpriv->SdioXmitThread = NULL
> 
> Shouldn't the function be returning an errror if this fails instead of
> relying on the pointer to be NULL?
> 
> And this is a "wrapper function" and only called in one place, why not
> just get rid of it entirely?  Same for rtl8723b_stop_thread()?

Hi Greg,

Thanks for the feedback. You're right, just setting the pointer to NULL 
just hides the error. The wrapper functions are unnecessary as well.

I will send a v3 that removes rtl8723b_start_thread(), 
rtl8723b_stop_thread(), rtw_hal_start_thread() and rtw_hal_stop_thread() 
entirely, inlining the kthread handling directly to 
rtw_start_drv_threads() and rtw_stop_drv_threads() with proper IS_ERR() 
checking.

Thanks,
Samasth.

> 
> thanks,
> 
> greg k-h