diff options
| author | Vineet Gupta <vgupta@synopsys.com> | 2015-10-17 15:29:59 +0530 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2017-08-28 15:17:36 -0700 |
| commit | c2bdac146b4f12d3f0065b865d5d36529c2cbfaa (patch) | |
| tree | c10a12d9cf0980261bfdb943f4666a031d87374e | |
| parent | ab1e8660c1bb2aa6ca3fbbc7e97cc2a5ffe1599b (diff) | |
ARC: spinlock: Document the EX based spin_unlock
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
| -rw-r--r-- | arch/arc/include/asm/spinlock.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h index 233d5ffe6ec7..968c730ef114 100644 --- a/arch/arc/include/asm/spinlock.h +++ b/arch/arc/include/asm/spinlock.h @@ -296,6 +296,12 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) */ smp_mb(); + /* + * EX is not really required here, a simple STore of 0 suffices. + * However this causes tasklist livelocks in SystemC based SMP virtual + * platforms where the systemc core scheduler uses EX as a cue for + * moving to next core. Do a git log of this file for details + */ __asm__ __volatile__( " ex %0, [%1] \n" : "+r" (val) |