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...
Changes in version 2:
- fixed up the error path for clk_prepare_enable() calls in xhci_plat_resume().
drivers/usb/host/xhci-plat.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
Index: usb/drivers/usb/host/xhci-plat.c
===================================================================
--- usb.orig/drivers/usb/host/xhci-plat.c
+++ usb/drivers/usb/host/xhci-plat.c
@@ -470,23 +470,36 @@ 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)
+ goto disable_clk;
}
ret = xhci_priv_resume_quirk(hcd);
if (ret)
- return ret;
+ goto disable_reg_clk;
ret = xhci_resume(xhci, 0);
if (ret)
- return ret;
+ goto disable_reg_clk;
pm_runtime_disable(dev);
pm_runtime_set_active(dev);
pm_runtime_enable(dev);
return 0;
+
+disable_reg_clk:
+ clk_disable_unprepare(xhci->reg_clk);
+
+disable_clk:
+ clk_disable_unprepare(xhci->clk);
+
+ return ret;
}
static int __maybe_unused xhci_plat_runtime_suspend(struct device *dev)
