Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash
From: peterz@infradead.org (Peter Zijlstra)
Date: 2018-08-30 14:29:28
Also in:
linux-arch, lkml
On Thu, Aug 30, 2018 at 03:23:55PM +0100, Will Deacon wrote:
quoted hunk ↗ jump to hunk
Yes, that would be worth trying. However, I also just noticed that the fetch-ops (which are now used to implement test_and_set_bit_lock()) seem to be missing the backwards branch in the LL/SC case. Yet another diff below. Will --->8diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h index 4e0072730241..f06c5ed672b3 100644 --- a/arch/arc/include/asm/atomic.h +++ b/arch/arc/include/asm/atomic.h@@ -84,7 +84,7 @@ static inline int atomic_fetch_##op(int i, atomic_t *v) \ "1: llock %[orig], [%[ctr]] \n" \ " " #asm_op " %[val], %[orig], %[i] \n" \ " scond %[val], [%[ctr]] \n" \ - " \n" \ + " bnz 1b \n" \ : [val] "=&r" (val), \ [orig] "=&r" (orig) \ : [ctr] "r" (&v->counter), \
ACK!! sorry about that, no idea how I messed that up. Also, once it all works, they should look at switching to _relaxed atomics for LL/SC.