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authorMichal Simek <monstr@monstr.eu>2009-12-10 12:07:02 +0100
committerMichal Simek <monstr@monstr.eu>2009-12-14 08:40:09 +0100
commitbf2d809668907c69b554459764b36584e4d57e4a (patch)
tree8f3e16925a34645ffd14e6d171937b37a06fba41 /arch/microblaze
parent519e9f417388ba055b7604db5f4f492f7c84f427 (diff)
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microblaze: Lockdep support
Microblaze needs to do lock_init very soon because MMU init calls lock functions. Here is the explanation from Peter Zijlstra why we have to enable __ARCH_WANTS_INTERRUPTS_ON_CTSW. "So we schedule while holding rq->lock (for obvious reasons), but since lockdep tracks held locks per tasks, we need to transfer the held state from the prev to the next task. We do this by explicity calling spin_release(&rq->lock) in context_switch() right before switch_to(), and calling spin_acquire(&rq->lock) in finish_task_switch()->finish_lock_switch(). Now, for some reason lockdep thinks that interrupts got enabled over the context switch (git grep __ARCH_WANTS_INTERRUPTS_ON_CTSW arch/microblaze doesn't seem to turn up anything). Clearly trying to acquire the rq->lock with interrupts enabled is a bad idea and lockdep warns you about this." Signed-off-by: Michal Simek <monstr@monstr.eu>
Diffstat (limited to 'arch/microblaze')
-rw-r--r--arch/microblaze/Kconfig3
-rw-r--r--arch/microblaze/include/asm/system.h2
-rw-r--r--arch/microblaze/kernel/setup.c2
3 files changed, 7 insertions, 0 deletions
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 8e1c4f7..5ba4dcd 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -60,6 +60,9 @@ config GENERIC_CSUM
config STACKTRACE_SUPPORT
def_bool y
+config LOCKDEP_SUPPORT
+ def_bool y
+
config PCI
def_bool n
diff --git a/arch/microblaze/include/asm/system.h b/arch/microblaze/include/asm/system.h
index b1ed615..1579706 100644
--- a/arch/microblaze/include/asm/system.h
+++ b/arch/microblaze/include/asm/system.h
@@ -16,6 +16,8 @@
#include <asm-generic/cmpxchg.h>
#include <asm-generic/cmpxchg-local.h>
+#define __ARCH_WANT_INTERRUPTS_ON_CTXSW
+
struct task_struct;
struct thread_info;
diff --git a/arch/microblaze/kernel/setup.c b/arch/microblaze/kernel/setup.c
index 367ad33..acd70fe 100644
--- a/arch/microblaze/kernel/setup.c
+++ b/arch/microblaze/kernel/setup.c
@@ -131,6 +131,8 @@ void __init machine_early_init(const char *cmdline, unsigned int ram,
strlcpy(cmd_line, cmdline, COMMAND_LINE_SIZE);
#endif
+ lockdep_init();
+
/* initialize device tree for usage in early_printk */
early_init_devtree((void *)_fdt_start);