Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
> On Fri, 13 Nov 2020 14:58:32 +0100 Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:
>
>> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>>
>> in_interrupt() is true for a variety of things including bottom half
>> disabled regions. Deducing hard interrupt context from it is dubious at
>> best.
>>
>> Use in_irq() which is true if called in hard interrupt context. Otherwise
>> calling irq_exit() would do more harm than good.
>>
>
> Gee, how to test it. Does anyone run current kernels on alpha?
Hold my beer:
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -134,8 +134,10 @@ common_shutdown_1(void *generic_ptr)
#ifdef CONFIG_DUMMY_CONSOLE
/* If we've gotten here after SysRq-b, leave interrupt
context before taking over the console. */
- if (in_irq())
+ if (in_irq()) {
+ printk ("in_irq(): true\n");
irq_exit();
+ }
/* This has the effect of resetting the VGA video origin. */
console_lock();
do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
and then sysrq-b over serial console:
[ 56.531250] sysrq: Resetting
[ 56.531250] in_irq(): true
[ 56.531250] Console: switching to colour dummy device 80x25
halted CPU 0
halt code = 5
HALT instruction executed
PC = fffffc0000310040
Resetting I/O buses...
>>>
Tested-by: Serge Belyshev <belyshev@xxxxxxxxxxxxxxxxx>
