On Tue, 5 Jul 2011 01:32:11 +0200 "Rafael J. Wysocki" <rjw@xxxxxxx> wrote: > > OK, below is an official version. > > Thanks, > Rafael > > --- > From: Rafael J. Wysocki <rjw@xxxxxxx> > Subject: ACPI: Fix lockdep false positives in acpi_power_off() > > All ACPICA locks are allocated and initialized by the same function, > acpi_os_create_lock(), with the help of a local variable called > "lock". Thus, when lockdep is enabled, it uses "lock" as the > name of all those locks and regards them as instances of the same > lock, which causes it to report possible locking problems with them > when there aren't any. > > To work around this problem, define acpi_os_create_lock() as a macro > and make it pass its argument to spin_lock_init(), so that lockdep > uses it as the name of the new lock. Define this macron in a > Linux-specific file to minimize the resulting modifications of > the OS-independent ACPICA parts. > > This change is based on an earlier patch from Andrea Righi and it > addresses a regression from 2.6.39 tracked as > https://bugzilla.kernel.org/show_bug.cgi?id=38152 > > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx> > Reported-by: Borislav Petkov <bp@xxxxxxxxx> > Tested-by: Andrea Righi <andrea@xxxxxxxxxxxxxxx> > --- > drivers/acpi/osl.c | 17 ----------------- > include/acpi/acpiosxf.h | 3 +++ > include/acpi/platform/aclinux.h | 18 ++++++++++++++++++ > 3 files changed, 21 insertions(+), 17 deletions(-) > > Index: linux-2.6/drivers/acpi/osl.c > =================================================================== > --- linux-2.6.orig/drivers/acpi/osl.c > +++ linux-2.6/drivers/acpi/osl.c > @@ -1333,23 +1333,6 @@ int acpi_resources_are_enforced(void) > EXPORT_SYMBOL(acpi_resources_are_enforced); > > /* > - * Create and initialize a spinlock. > - */ > -acpi_status > -acpi_os_create_lock(acpi_spinlock *out_handle) > -{ > - spinlock_t *lock; > - > - lock = ACPI_ALLOCATE(sizeof(spinlock_t)); > - if (!lock) > - return AE_NO_MEMORY; > - spin_lock_init(lock); > - *out_handle = lock; > - > - return AE_OK; > -} > - > -/* > * Deallocate the memory for a spinlock. > */ > void acpi_os_delete_lock(acpi_spinlock handle) > Index: linux-2.6/include/acpi/acpiosxf.h > =================================================================== > --- linux-2.6.orig/include/acpi/acpiosxf.h > +++ linux-2.6/include/acpi/acpiosxf.h > @@ -98,8 +98,11 @@ acpi_os_table_override(struct acpi_table > /* > * Spinlock primitives > */ > + > +#ifndef acpi_os_create_lock > acpi_status > acpi_os_create_lock(acpi_spinlock *out_handle); > +#endif > > void acpi_os_delete_lock(acpi_spinlock handle); > > Index: linux-2.6/include/acpi/platform/aclinux.h > =================================================================== > --- linux-2.6.orig/include/acpi/platform/aclinux.h > +++ linux-2.6/include/acpi/platform/aclinux.h > @@ -159,6 +159,24 @@ static inline void *acpi_os_acquire_obje > } while (0) > #endif > > +/* > + * When lockdep is enabled, the spin_lock_init() macro stringifies it's > + * argument and uses that as a name for the lock in debugging. > + * By executing spin_lock_init() in a macro the key changes from "lock" for > + * all locks to the name of the argument of acpi_os_create_lock(), which > + * prevents lockdep from reporting false positives for ACPICA locks. > + */ > +#define acpi_os_create_lock(__handle) \ > +({ \ > + spinlock_t *lock = ACPI_ALLOCATE(sizeof(*lock)); \ > + \ > + if (lock) { \ > + *(__handle) = lock; \ > + spin_lock_init(*(__handle)); \ > + } \ > + lock ? AE_OK : AE_NO_MEMORY; \ > +}) > + > #endif /* __KERNEL__ */ > > #endif /* __ACLINUX_H__ */ Since I made the effort of digging into the lockdep code, you can actually add my Reviewed-by: Florian Mickler <florian@xxxxxxxxxxx> Regards, Flo -- 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
