The patch titled
Subject: lib/test_lockup.c: minimum fix to get it compiled on PREEMPT_RT
has been added to the -mm tree. Its filename is
lib-test_lockup-minimum-fix-to-get-it-compiled-on-preempt_rt.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/lib-test_lockup-minimum-fix-to-get-it-compiled-on-preempt_rt.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/lib-test_lockup-minimum-fix-to-get-it-compiled-on-preempt_rt.patch
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------------------------------------------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Subject: lib/test_lockup.c: minimum fix to get it compiled on PREEMPT_RT
On PREEMPT_RT the locks are quite different so they can't be tested as it
is done below. The alternative is to test for the waitlock within
rtmutex.
This is the bare minimun to get it compiled. Problems which exist on
PREEMP_RT:
- none of the locks (spinlock_t, rwlock_t, mutex_t, rw_semaphore) may be
acquired with disabled preemption or interrupts.
If I read the code correct the it is possible to acquire a mutex_t with
disabled interrupts.
I don't know how to obtain a lock pointer. Technically they are not
exported to userland.
- memory can not be allocated with disabled preemption or interrupts
even with GFP_ATOMIC.
Link: https://lkml.kernel.org/r/20201028181041.xyeothhkouc3p4md@xxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_lockup.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/lib/test_lockup.c~lib-test_lockup-minimum-fix-to-get-it-compiled-on-preempt_rt
+++ a/lib/test_lockup.c
@@ -480,6 +480,21 @@ static int __init test_lockup_init(void)
return -EINVAL;
#ifdef CONFIG_DEBUG_SPINLOCK
+#ifdef CONFIG_PREEMPT_RT
+ if (test_magic(lock_spinlock_ptr,
+ offsetof(spinlock_t, lock.wait_lock.magic),
+ SPINLOCK_MAGIC) ||
+ test_magic(lock_rwlock_ptr,
+ offsetof(rwlock_t, rtmutex.wait_lock.magic),
+ SPINLOCK_MAGIC) ||
+ test_magic(lock_mutex_ptr,
+ offsetof(struct mutex, lock.wait_lock.magic),
+ SPINLOCK_MAGIC) ||
+ test_magic(lock_rwsem_ptr,
+ offsetof(struct rw_semaphore, rtmutex.wait_lock.magic),
+ SPINLOCK_MAGIC))
+ return -EINVAL;
+#else
if (test_magic(lock_spinlock_ptr,
offsetof(spinlock_t, rlock.magic),
SPINLOCK_MAGIC) ||
@@ -494,6 +509,7 @@ static int __init test_lockup_init(void)
SPINLOCK_MAGIC))
return -EINVAL;
#endif
+#endif
if ((wait_state != TASK_RUNNING ||
(call_cond_resched && !reacquire_locks) ||
_
Patches currently in -mm which might be from bigeasy@xxxxxxxxxxxxx are
lib-test_lockup-minimum-fix-to-get-it-compiled-on-preempt_rt.patch
