linux-kernel - Re: [PATCH 21/24] usb: host: xhci: Move array of structs from the stack onto the heap

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Message-ID: <20210601092513.GC543307@dell>
Date:   Tue, 1 Jun 2021 10:25:13 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     Sergei Shtylyov <sergei.shtylyov@...il.com>,
        linux-kernel@...r.kernel.org,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH 21/24] usb: host: xhci: Move array of structs from the
 stack onto the heap

On Thu, 27 May 2021, Mathias Nyman wrote:

> On 26.5.2021 18.28, Lee Jones wrote:
> > On Wed, 26 May 2021, Sergei Shtylyov wrote:
> > 
> >> On 5/26/21 5:44 PM, Lee Jones wrote:
> >>
> >> [...]
> >>>>> Fixes the following W=1 kernel build warning(s):
> >>>>>
> >>>>>  drivers/usb/host/xhci.c: In function ‘xhci_reserve_bandwidth’:
> >>>>>  drivers/usb/host/xhci.c:2859:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]
> >>>>>
> >>>>> Cc: Mathias Nyman <mathias.nyman@...el.com>
> >>>>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> >>>>> Cc: linux-usb@...r.kernel.org
> >>>>> Signed-off-by: Lee Jones <lee.jones@...aro.org>
> >>>>> ---
> >>>>>  drivers/usb/host/xhci.c | 8 +++++++-
> >>>>>  1 file changed, 7 insertions(+), 1 deletion(-)
> >>>>>
> >>>>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> >>>>> index ac2a7d4288883..40ce4b4eb12ad 100644
> >>>>> --- a/drivers/usb/host/xhci.c
> >>>>> +++ b/drivers/usb/host/xhci.c
> >>>> [...]
> >>>>> @@ -2788,6 +2788,10 @@ static int xhci_reserve_bandwidth(struct xhci_hcd *xhci,
> >>>>>  		return -ENOMEM;
> >>>>>  	}
> >>>>>  
> >>>>> +	ep_bw_info = kzalloc(sizeof(*ep_bw_info) * 31, GFP_KERNEL);
> 
> GFP_KERNEL might not be suitable for all cases.
> 
> xhci_reserve_bandwidth() is called from xhci_configure_endpoint(), which again
> is called from a lot of places.
> For example from xhci_update_hub_device() which can be called with GFP_NOIO mem_flags.

What do you suggest as an alternative?

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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