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

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Message-ID: <2026010936-koala-recharger-ca16@gregkh>
Date: Fri, 9 Jan 2026 05:50:41 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Samasth Norway Ananda <samasth.norway.ananda@...cle.com>
Cc: dan.carpenter@...aro.org, linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] staging: rtl8723bs: add IS_ERR() check for
 kthread_run()

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()?

thanks,

greg k-h