On 6/30/23 12:10 AM, 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...
>
> 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@xxxxxx>
>
> ---
> This patch is against the 'usb-linus' branch of Greg KH's 'usb.git' repo...
>
> drivers/usb/host/xhci-plat.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> Index: usb/drivers/usb/host/xhci-plat.c
> ===================================================================
> --- usb.orig/drivers/usb/host/xhci-plat.c
> +++ usb/drivers/usb/host/xhci-plat.c
> @@ -470,8 +470,14 @@ static int __maybe_unused xhci_plat_resu
> int ret;
>
> if (!device_may_wakeup(dev) && (xhci->quirks & XHCI_SUSPEND_RESUME_CLKS)) {
> - clk_prepare_enable(xhci->clk);
> - clk_prepare_enable(xhci->reg_clk);
> + ret = clk_prepare_enable(xhci->clk);
> + if (ret)
> + return ret;
> + ret = clk_prepare_enable(xhci->reg_clk);
> + if (ret) {
> + clk_disable_unprepare(xhci->clk);
> + return ret;
> + }
Scratch that, please! I didn't realize in time I have to disable/unprepare
the clocks on the errors occuring below as well, not just return as before... :-/
> }
>
> ret = xhci_priv_resume_quirk(hcd);
>
MBR, Sergey
