Hi, > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- > owner@xxxxxxxxxxxxxxx] On Behalf Of Zheng, Lv > Subject: RE: [PATCH v3 1/5] ACPI: change __init to __ref for > early_acpi_os_unmap_memory() > > Hi, > > > -----Original Message----- > > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- > > owner@xxxxxxxxxxxxxxx] On Behalf Of Aleksey Makarov > > Sent: Tuesday, February 16, 2016 2:05 AM > > To: linux-acpi@xxxxxxxxxxxxxxx > > Cc: linux-serial@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm- > > kernel@xxxxxxxxxxxxxxxxxxx; Aleksey Makarov <aleksey.makarov@xxxxxxxxxx>; > > Russell King <linux@xxxxxxxxxxxxxxxx>; Greg Kroah-Hartman > > <gregkh@xxxxxxxxxxxxxxxxxxx>; Rafael J . Wysocki <rjw@xxxxxxxxxxxxx>; Leif > > Lindholm <leif.lindholm@xxxxxxxxxx>; Graeme Gregory > > <graeme.gregory@xxxxxxxxxx>; Al Stone <ahs3@xxxxxxxxxx>; Christopher > > Covington <cov@xxxxxxxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx> > > Subject: [PATCH v3 1/5] ACPI: change __init to __ref for > > early_acpi_os_unmap_memory() > > > > early_acpi_os_unmap_memory() is marked as __init because it calls > > __acpi_unmap_table(), but only when acpi_gbl_permanent_mmap is not set. > > > > acpi_gbl_permanent_mmap is set in __init acpi_early_init() > > so it is safe to call early_acpi_os_unmap_memory() from anywhere > > > > We need this function to be non-__init because we need access to > > some tables at unpredictable time--it may be before or after > > acpi_gbl_permanent_mmap is set. For example, SPCR (Serial Port Console > > Redirection) table is needed each time a new console is registered. > > It can be quite early (console_initcall) or when a module is inserted. > > When this table accessed before acpi_gbl_permanent_mmap is set, > > the pointer should be unmapped. This is exactly what this function > > does. > [Lv Zheng] > Why don't you use another API instead of early_acpi_os_unmap_memory() in > case you want to unmap things in any cases. > acpi_os_unmap_memory() should be the one to match this purpose. > It checks acpi_gbl_ppermanent_mmap in acpi_os_unmap_iomem(). > And in fact early_acpi_os_unmap_memory() should be removed. [Lv Zheng] One more thing is: If you can't switch your driver to use acpi_os_unmap_memory() instead of early_acpi_os_unmap_memory(), then it implies that your driver does have a defect. There is an early bootup requirement in Linux. Maps acquired during the early stage should be freed by the driver during the early stage. And the driver should re-acquire the memory map after booting. This is because, during early bootup stage, there are only limited slots available for drivers to map memory. So by changing __init to __ref here, you probably will hide many such defects. And solving issues in this way doesn't seem to be an improvement. Thanks and best regards -Lv > > Thanks and best regards > -Lv > > > > > Signed-off-by: Aleksey Makarov <aleksey.makarov@xxxxxxxxxx> > > --- > > drivers/acpi/osl.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c > > index 67da6fb..8a552cd 100644 > > --- a/drivers/acpi/osl.c > > +++ b/drivers/acpi/osl.c > > @@ -497,7 +497,11 @@ void __ref acpi_os_unmap_memory(void *virt, > > acpi_size size) > > } > > EXPORT_SYMBOL_GPL(acpi_os_unmap_memory); > > > > -void __init early_acpi_os_unmap_memory(void __iomem *virt, acpi_size > size) > > +/* > > + * acpi_gbl_permanent_mmap is set in __init acpi_early_init() > > + * so it is safe to call early_acpi_os_unmap_memory() from anywhere > > + */ > > +void __ref early_acpi_os_unmap_memory(void __iomem *virt, acpi_size > size) > > { > > if (!acpi_gbl_permanent_mmap) > > __acpi_unmap_table(virt, size); > > -- > > 2.7.1 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
