lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 4 Jul 2011 00:28:23 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Andrea Righi <andrea@...terlinux.com>
Cc:	Len Brown <lenb@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Maciej Rutecki <maciej.rutecki@...il.com>,
	Florian Mickler <florian@...kler.org>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ACPI: fix acpi_power_off lockdep splat

On Monday, July 04, 2011, Rafael J. Wysocki wrote:
> On Sunday, July 03, 2011, Rafael J. Wysocki wrote:
> > On Sunday, July 03, 2011, Andrea Righi wrote:
> > > Implement acpi_os_create_lock() as a C-preprocessor macro to suppress
> > > lockdep false positive.
> > > 
> > > When lockdep is enabled the spin_lock_init macro stringifies it's
> > > argument and uses that as a name for the lock in the debugging.
> > > 
> > > By executing spin_lock_init in a macro the key changes from "lock" for
> > > all locks to the actual argument of acpi_os_create_lock()
> > > ("&acpi_gbl_global_lock_pending_lock", "&acpi_gbl_gpe_lock" or
> > > "&acpi_gbl_hardware_lock" for now).
> > > 
> > > This fixes:
> > > https://bugzilla.kernel.org/show_bug.cgi?id=38152
> > > 
> > > ChangeLog (v1 -> v2):
> > >  - avoid to call spin_lock_init multiple times on the same lock
> > >  - rewrite patch description (thanks to Florian for providing a better
> > >    description of the patch)
> > > 
> > > Reported-by: Borislav Petkov <bp@...en8.de>
> > > CC: Florian Mickler <florian@...kler.org>
> > > Signed-off-by: Andrea Righi <andrea@...terlinux.com>
> > > ---
> > >  drivers/acpi/osl.c      |    3 +--
> > >  include/acpi/acpiosxf.h |   12 +++++++++++-
> > >  2 files changed, 12 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> > > index 52ca964..4c985d3 100644
> > > --- a/drivers/acpi/osl.c
> > > +++ b/drivers/acpi/osl.c
> > > @@ -1336,14 +1336,13 @@ EXPORT_SYMBOL(acpi_resources_are_enforced);
> > >   * Create and initialize a spinlock.
> > >   */
> > >  acpi_status
> > > -acpi_os_create_lock(acpi_spinlock *out_handle)
> > > +__acpi_os_create_lock(acpi_spinlock *out_handle)
> > >  {
> > 
> > I would rename this to acpi_os_allocate_lock() or acpi_os_alloc_lock(),
> > so that it doesn't suggest the lock is initialized by this function.
> > 
> > Hmm.  There's one more thing we need to take into account here.  Namely,
> > include/acpi/acpiosxf.h is used by other OSes, so we shouldn't put
> > Linux-specific stuff into it.
> > 
> > I'm not sure how to work around that at the moment.
> 
> OK, the patch below builds for me and seems to work even, although I haven't
> tested it with lockdep on.

Below is a cleaned-up version, still untested with lockdep on.

Thanks,
Rafael

---
 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__ */
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists