2012-02-01 05:20:05

by Geunsik Lim

Subject: [PATCH] Fix logical and operator at interrupt handler thread

From: Geunsik Lim <[email protected]>

'&' is a bitwise operation. (e.g: a & b )
Use '&&' and-operator instead of '&' bitwise operator.

Signed-off-by: Geunsik Lim <[email protected]>
---
kernel/irq/manage.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index a9a9dbe..c0730ad 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -773,7 +773,7 @@ static int irq_thread(void *data)
struct irqaction *action);
int wake;

- if (force_irqthreads & test_bit(IRQTF_FORCED_THREAD,
+ if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
&action->thread_flags))
handler_fn = irq_forced_thread_fn;
else
--
1.7.8.1

2012-02-01 05:41:38

by Eric Dumazet

Subject: Re: [PATCH] Fix logical and operator at interrupt handler thread

Le mercredi 01 février 2012 à 14:19 +0900, Geunsik Lim a écrit :
> From: Geunsik Lim <[email protected]>
>
> '&' is a bitwise operation. (e.g: a & b )
> Use '&&' and-operator instead of '&' bitwise operator.
>
> Signed-off-by: Geunsik Lim <[email protected]>
> ---
> kernel/irq/manage.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> index a9a9dbe..c0730ad 100644
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -773,7 +773,7 @@ static int irq_thread(void *data)
> struct irqaction *action);
> int wake;
>
> - if (force_irqthreads & test_bit(IRQTF_FORCED_THREAD,
> + if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
> &action->thread_flags))
> handler_fn = irq_forced_thread_fn;
> else


This was intentional, to have a single conditional move :

ffffffff810b0868: 0f b6 15 19 f5 bd 00 movzbl 0xbdf519(%rip),%edx # ffffffff81c8fd88 <force_irqthreads>
ffffffff810b086f: 49 89 c5 mov %rax,%r13
ffffffff810b0872: 48 8b 43 40 mov 0x40(%rbx),%rax
ffffffff810b0876: be 01 00 00 00 mov $0x1,%esi
ffffffff810b087b: 48 c1 e8 04 shr $0x4,%rax
ffffffff810b087f: 85 c2 test %eax,%edx
ffffffff810b0881: 48 c7 c0 80 0a 0b 81 mov $0xffffffff810b0a80,%rax
ffffffff810b0888: 48 c7 c2 40 dc 80 81 mov $0xffffffff8180dc40,%rdx
ffffffff810b088f: 4c 0f 44 f8 cmove %rax,%r15


I guess you could instead use jump_label here to shorten the code.

2012-02-01 05:53:41

by Eric Dumazet

Subject: Re: [PATCH] Fix logical and operator at interrupt handler thread

Le mercredi 01 février 2012 à 06:41 +0100, Eric Dumazet a écrit :

> I guess you could instead use jump_label here to shorten the code.

(since its not hot path anyway, its probably not worth it)