[PATCH] irq_work: improve the flag definitions

[PATCH] irq_work: improve the flag definitions

[Bartosz Golaszewski]

IRQ_WORK_FLAGS is defined simply to 3UL. This is confusing as it
says nothing about its purpose. Define IRQ_WORK_FLAGS as a bitwise
OR of IRQ_WORK_PENDING and IRQ_WORK_BUSY.

While we're at it: use the BIT() macro for all flags.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 include/linux/irq_work.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
index 47b9ebd4a74f..467a58e7e0da 100644
--- a/include/linux/irq_work.h
+++ b/include/linux/irq_work.h
@@ -12,10 +12,10 @@
  * busy      NULL, 2 -> {free, claimed} : callback in progress, can be claimed
  */
 
-#define IRQ_WORK_PENDING	1UL
-#define IRQ_WORK_BUSY		2UL
-#define IRQ_WORK_FLAGS		3UL
-#define IRQ_WORK_LAZY		4UL /* Doesn't want IPI, wait for tick */
+#define IRQ_WORK_PENDING	BIT(0)
+#define IRQ_WORK_BUSY		BIT(1)
+#define IRQ_WORK_FLAGS		(IRQ_WORK_PENDING | IRQ_WORK_BUSY)
+#define IRQ_WORK_LAZY		BIT(3) /* Doesn't want IPI, wait for tick */
 
 struct irq_work {
 	unsigned long flags;
-- 
2.13.2

Re: [PATCH] irq_work: improve the flag definitions

[Andy Shevchenko]

On Mon, Aug 14, 2017 at 2:56 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> IRQ_WORK_FLAGS is defined simply to 3UL. This is confusing as it
> says nothing about its purpose. Define IRQ_WORK_FLAGS as a bitwise
> OR of IRQ_WORK_PENDING and IRQ_WORK_BUSY.
>
> While we're at it: use the BIT() macro for all flags.

> +#define IRQ_WORK_PENDING       BIT(0)
> +#define IRQ_WORK_BUSY          BIT(1)
> +#define IRQ_WORK_FLAGS         (IRQ_WORK_PENDING | IRQ_WORK_BUSY)

I dunno which style is preferred, though I would go with simple
GENMASK() here, as all definitions right on left :-)

Parameters of GENMASK will show last-first entries and can be easily decoded.
Although there are only two for now.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] irq_work: improve the flag definitions

[Bartosz Golaszewski]

2017-08-14 14:19 GMT+02:00 Andy Shevchenko <andy.shevchenko@gmail.com>:
> On Mon, Aug 14, 2017 at 2:56 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>> IRQ_WORK_FLAGS is defined simply to 3UL. This is confusing as it
>> says nothing about its purpose. Define IRQ_WORK_FLAGS as a bitwise
>> OR of IRQ_WORK_PENDING and IRQ_WORK_BUSY.
>>
>> While we're at it: use the BIT() macro for all flags.
>
>> +#define IRQ_WORK_PENDING       BIT(0)
>> +#define IRQ_WORK_BUSY          BIT(1)
>> +#define IRQ_WORK_FLAGS         (IRQ_WORK_PENDING | IRQ_WORK_BUSY)
>
> I dunno which style is preferred, though I would go with simple
> GENMASK() here, as all definitions right on left :-)
>
> Parameters of GENMASK will show last-first entries and can be easily decoded.
> Although there are only two for now.
>

Which is a good enough reason to not over-complicate things and just
use an easy to decipher bitwise OR. ;)

Thanks,
Bartosz

Re: [PATCH] irq_work: improve the flag definitions

[Bartosz Golaszewski]

2017-08-14 13:56 GMT+02:00 Bartosz Golaszewski <brgl@bgdev.pl>:
> IRQ_WORK_FLAGS is defined simply to 3UL. This is confusing as it
> says nothing about its purpose. Define IRQ_WORK_FLAGS as a bitwise
> OR of IRQ_WORK_PENDING and IRQ_WORK_BUSY.
>
> While we're at it: use the BIT() macro for all flags.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> ---
>  include/linux/irq_work.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
> index 47b9ebd4a74f..467a58e7e0da 100644
> --- a/include/linux/irq_work.h
> +++ b/include/linux/irq_work.h
> @@ -12,10 +12,10 @@
>   * busy      NULL, 2 -> {free, claimed} : callback in progress, can be claimed
>   */
>
> -#define IRQ_WORK_PENDING       1UL
> -#define IRQ_WORK_BUSY          2UL
> -#define IRQ_WORK_FLAGS         3UL
> -#define IRQ_WORK_LAZY          4UL /* Doesn't want IPI, wait for tick */
> +#define IRQ_WORK_PENDING       BIT(0)
> +#define IRQ_WORK_BUSY          BIT(1)
> +#define IRQ_WORK_FLAGS         (IRQ_WORK_PENDING | IRQ_WORK_BUSY)
> +#define IRQ_WORK_LAZY          BIT(3) /* Doesn't want IPI, wait for tick */

Superseded by v2 - 4UL is BIT(2), not BIT(3).

Best regards,
Bartosz Golaszewski

[PATCH] irq_work: Improve the flag definitions

[Frederic Weisbecker]

From: Bartosz Golaszewski <brgl@bgdev.pl>

IRQ_WORK_FLAGS is defined simply to 3UL. This is confusing as it
says nothing about its purpose. Define IRQ_WORK_FLAGS as a bitwise
OR of IRQ_WORK_PENDING and IRQ_WORK_BUSY and change its name to
IRQ_WORK_CLAIMED.

While we're at it: use the BIT() macro for all flags.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/irq_work.h | 8 ++++----
 kernel/irq_work.c        | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
index 0e81035..de63339 100644
--- a/include/linux/irq_work.h
+++ b/include/linux/irq_work.h
@@ -13,10 +13,10 @@
  * busy      NULL, 2 -> {free, claimed} : callback in progress, can be claimed
  */
 
-#define IRQ_WORK_PENDING	1UL
-#define IRQ_WORK_BUSY		2UL
-#define IRQ_WORK_FLAGS		3UL
-#define IRQ_WORK_LAZY		4UL /* Doesn't want IPI, wait for tick */
+#define IRQ_WORK_PENDING	BIT(0)
+#define IRQ_WORK_BUSY		BIT(1)
+#define IRQ_WORK_CLAIMED	(IRQ_WORK_PENDING | IRQ_WORK_BUSY)
+#define IRQ_WORK_LAZY		BIT(2) /* Doesn't want IPI, wait for tick */
 
 struct irq_work {
 	unsigned long flags;
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 40e9d73..6b7cdf1 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -36,7 +36,7 @@ static bool irq_work_claim(struct irq_work *work)
 	 */
 	flags = work->flags & ~IRQ_WORK_PENDING;
 	for (;;) {
-		nflags = flags | IRQ_WORK_FLAGS;
+		nflags = flags | IRQ_WORK_CLAIMED;
 		oflags = cmpxchg(&work->flags, flags, nflags);
 		if (oflags == flags)
 			break;
-- 
2.7.4