The function apple_airport_reset is not called in atomic context.
Thus mdelay can be replaced with usleep_range, to avoid busy wait.
This is reported by a static analysis tool named DCNS written by myself.
Signed-off-by: Jia-Ju Bai <[email protected]>
---
arch/x86/kernel/early-quirks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 1e82f78..559e81a 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -604,7 +604,7 @@ static void __init apple_airport_reset(int bus, int slot, int func)
if ((pmcsr & PCI_PM_CTRL_STATE_MASK) != PCI_D0) {
pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
write_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL, pmcsr);
- mdelay(10);
+ usleep_range(10000, 11000);
pmcsr = read_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL);
if ((pmcsr & PCI_PM_CTRL_STATE_MASK) != PCI_D0) {
--
1.7.9.5
On Wed, Jan 24, 2018 at 10:38:22AM +0800, Jia-Ju Bai wrote:
> The function apple_airport_reset is not called in atomic context.
> Thus mdelay can be replaced with usleep_range, to avoid busy wait.
>
> This is reported by a static analysis tool named DCNS written by myself.
No, usleep_range() is built on hrtimers and at this point in the
boot sequence we haven't called hrtimers_init() yet.
Look at init/main.c:start_kernel() and note that setup_arch()
(which calls early_quirks()) is called way before hrtimers_init().
Please amend your static checker to consider every call to mdelay()
that occurs before hrtimers_init() a false positive, or manually
verify each patch for this constraint before submission.
I'll test your patch later today on my MacBook Pro but I suspect
it'll cause a boot crash or hang. In any case the choice of mdelay()
here was deliberate.
Thanks,
Lukas
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> arch/x86/kernel/early-quirks.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
> index 1e82f78..559e81a 100644
> --- a/arch/x86/kernel/early-quirks.c
> +++ b/arch/x86/kernel/early-quirks.c
> @@ -604,7 +604,7 @@ static void __init apple_airport_reset(int bus, int slot, int func)
> if ((pmcsr & PCI_PM_CTRL_STATE_MASK) != PCI_D0) {
> pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
> write_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL, pmcsr);
> - mdelay(10);
> + usleep_range(10000, 11000);
>
> pmcsr = read_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL);
> if ((pmcsr & PCI_PM_CTRL_STATE_MASK) != PCI_D0) {
> --
> 1.7.9.5
>
On Wed, Jan 24, 2018 at 7:33 AM, Lukas Wunner <[email protected]> wrote:
> On Wed, Jan 24, 2018 at 10:38:22AM +0800, Jia-Ju Bai wrote:
> Please amend your static checker to consider every call to mdelay()
> that occurs before hrtimers_init() a false positive, or manually
> verify each patch for this constraint before submission.
> In any case the choice of mdelay() here was deliberate.
Perhaps, we need to put a comment for the next "Markus Elfring" crawler.
--
With Best Regards,
Andy Shevchenko