Commit bf2d8096 authored by Michal Simek's avatar Michal Simek

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: default avatarMichal Simek <monstr@monstr.eu>
parent 519e9f41
...@@ -60,6 +60,9 @@ config GENERIC_CSUM ...@@ -60,6 +60,9 @@ config GENERIC_CSUM
config STACKTRACE_SUPPORT config STACKTRACE_SUPPORT
def_bool y def_bool y
config LOCKDEP_SUPPORT
def_bool y
config PCI config PCI
def_bool n def_bool n
......
...@@ -16,6 +16,8 @@ ...@@ -16,6 +16,8 @@
#include <asm-generic/cmpxchg.h> #include <asm-generic/cmpxchg.h>
#include <asm-generic/cmpxchg-local.h> #include <asm-generic/cmpxchg-local.h>
#define __ARCH_WANT_INTERRUPTS_ON_CTXSW
struct task_struct; struct task_struct;
struct thread_info; struct thread_info;
......
...@@ -131,6 +131,8 @@ void __init machine_early_init(const char *cmdline, unsigned int ram, ...@@ -131,6 +131,8 @@ void __init machine_early_init(const char *cmdline, unsigned int ram,
strlcpy(cmd_line, cmdline, COMMAND_LINE_SIZE); strlcpy(cmd_line, cmdline, COMMAND_LINE_SIZE);
#endif #endif
lockdep_init();
/* initialize device tree for usage in early_printk */ /* initialize device tree for usage in early_printk */
early_init_devtree((void *)_fdt_start); early_init_devtree((void *)_fdt_start);
......
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