lib/test_lockup.c: minimum fix to get it compiled on PREEMPT_RT
authorSebastian Andrzej Siewior <bigeasy@linutronix.de>
Wed, 16 Dec 2020 04:43:13 +0000 (20:43 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 16 Dec 2020 06:46:16 +0000 (22:46 -0800)
commit45e3d5a2af1d53164cc5fbd22c5ceea0d163ad45
treebfd7a5bf7e457fa0b9642571fe04dc34dc90c247
parent180644f80a0284bf5c9acdbd33760924fef14236
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@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lib/test_lockup.c