Re: [PATCH v4] usb: host: xhci-plat: fix possible kernel oops while resuming

[Sergey Shtylyov <s.shtylyov@omp.ru>]

On 7/11/23 10:18 PM, Sergey Shtylyov wrote:

> If this driver enables the xHC clocks while resuming from sleep, it calls
> clk_prepare_enable() without checking for errors and blithely goes on to
> read/write the xHC's registers -- which, with the xHC not being clocked,
> at least on ARM32 usually causes an imprecise external abort exceptions
> which cause kernel oops.  Currently, the chips for which the driver does
> the clock dance on suspend/resume seem to be the Broadcom STB SoCs, based
> on ARM32 CPUs, as it seems...
> 
> In order to fix this issue, add the result checks for clk_prepare_enable()
> calls in xhci_plat_resume(), add conditional clk_disable_unprepare() calls
> on the error path of xhci_plat_resume(); then factor out the common clock
> disabling code from the suspend() and resume() driver PM methods into a
> separate function to avoid code duplication.
> 
> Found by Linux Verification Center (linuxtesting.org) with the Svace static
> analysis tool.
> 
> Fixes: 8bd954c56197 ("usb: host: xhci-plat: suspend and resume clocks")
> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> 
> ---
> This patch is against the 'usb-linus' branch of Greg KH's 'usb.git' repo...

   The v4 of the patch was posted almost 2 months ago... What's going on,
is Mathias still opn vacations?

[...]

MBR, Sergey