Message-ID: <bf3296be-10f7-5a43-5ae8-dfc5b6d41240@quicinc.com>
Date:   Fri, 10 Feb 2023 12:26:52 +0530
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Subject: Re: [PATCH] usb: gadget: u_serial: Add null pointer check in
 gserial_resume
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From:   Prashanth K <quic_prashk@quicinc.com>
To:     Alan Stern <stern@rowland.harvard.edu>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Xiu Jianfeng <xiujianfeng@huawei.com>,
        Pratham Pratap <quic_ppratap@quicinc.com>,
        Jack Pham <quic_jackp@quicinc.com>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <482f2c32-41d1-f07e-ee3f-3eb9aee76ac7@quicinc.com>
 <Y+QEQBxlr6FZ58DK@rowland.harvard.edu>
 <542ee8a6-598c-ca17-6d75-5eca2b34133a@quicinc.com>
 <Y+SaZrDmaqB0U2QA@kroah.com>
 <f32398bb-62f3-12fd-4b81-7ce7bdf4706a@quicinc.com>
 <e7dde0aa-c1e2-dd6c-94a1-1e9049f0a5fb@quicinc.com>
 <Y+UMkA9iaJTWVQ5u@rowland.harvard.edu>
 <5ad875be-079c-7f91-ede9-68f954cc7f34@quicinc.com>
 <Y+UZQvuh8KR4gE4P@rowland.harvard.edu>
 <71f624df-5302-8276-2a2a-96223d4ba3c7@quicinc.com>
 <Y+VgHdJjrd0ZvY33@rowland.harvard.edu>
 <53d48954-3f7e-fd02-5e8e-2912c16565b3@quicinc.com>
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> And this seems like a viable option to me, what do you suggest?
> 
> gserial_disconnect {
>      spin_lock(static)
>      spin_lock(port)
>      ...
>      gser->ioport = NULL;
>      ...
>      spin_lock(port)
>      spin_unlock(static)
> 
> }
> 
> gserial_resume {
>      struct gs_port *port = gser->ioport;
> 
>      spin_lock(static)
>      if (!port)
	   spin_unlock(static)
>          return
>      spin_lock(port)
> 
>      ...
>      spin_unlock(port)
>      spin_unlock(static)
> }
> 
> Thanks,
> Prashanth K
Small correction inlined.