diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-11-19 11:09:45 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-11-27 09:24:18 +0100 |
| commit | 419123f900dac58fb27ce5285b21074f5300095a (patch) | |
| tree | d0b0d72691d4e2e3df0e9f4d2e335bebc378fdeb /arch/s390/kernel/entry.S | |
| parent | c6f70d3b8a32fdec60d3f78cb59423f056f16688 (diff) | |
s390/spinlock: do not yield to a CPU in udelay/mdelay
It does not make sense to try to relinquish the time slice with diag 0x9c
to a CPU in a state that does not allow to schedule the CPU. The scenario
where this can happen is a CPU waiting in udelay/mdelay while holding a
spin-lock.
Add a CIF bit to tag a CPU in enabled wait and use it to detect that the
yield of a CPU will not be successful and skip the diagnose call.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/entry.S')
| -rw-r--r-- | arch/s390/kernel/entry.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 857b6526d298..cd5a191381b9 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -764,6 +764,7 @@ ENTRY(psw_idle) .insn rsy,0xeb0000000017,%r1,5,__SF_EMPTY+16(%r15) .Lpsw_idle_stcctm: #endif + oi __LC_CPU_FLAGS+7,_CIF_ENABLED_WAIT STCK __CLOCK_IDLE_ENTER(%r2) stpt __TIMER_IDLE_ENTER(%r2) .Lpsw_idle_lpsw: @@ -1146,6 +1147,7 @@ cleanup_critical: .quad .Lio_done - 4 .Lcleanup_idle: + ni __LC_CPU_FLAGS+7,255-_CIF_ENABLED_WAIT # copy interrupt clock & cpu timer mvc __CLOCK_IDLE_EXIT(8,%r2),__LC_INT_CLOCK mvc __TIMER_IDLE_EXIT(8,%r2),__LC_ASYNC_ENTER_TIMER |