[PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[Kefeng Wang]

Most ARCHs support SPARSE_IRQ, and MAY_HAVE_SPARSE_IRQ is useless, and
only sh and csky select it, but the could use SPARSE_IRQ too, let's
kill MAY_HAVE_SPARSE_IRQ, also cleanup the kernel/irq/Kconfig a little.

Kefeng Wang (3):
  sh: Cleanup about SPARSE_IRQ
  csky: Use SPARSE_IRQ
  genirq: Cleanup Kconfig

 arch/csky/Kconfig         |  2 +-
 arch/sh/Kconfig           |  1 -
 arch/sh/include/asm/irq.h |  9 -------
 kernel/irq/Kconfig        | 50 ++++++++++++++++-----------------------
 4 files changed, 21 insertions(+), 41 deletions(-)

-- 
2.26.2

[PATCH 1/3] sh: Cleanup about SPARSE_IRQ

[Kefeng Wang]

After commit 37744feebc08 ("sh: remove sh5 support"), sh always
enable SPARSE_IRQ, kill unused MAY_HAVE_SPARSE_IRQ and NR_IRQS
define under !CONFIG_SPARSE_IRQ.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/sh/Kconfig           | 1 -
 arch/sh/include/asm/irq.h | 9 ---------
 2 files changed, 10 deletions(-)

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6904f4bdbf00..70afb30e0b32 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -56,7 +56,6 @@ config SUPERH
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select IRQ_FORCED_THREADING
-	select MAY_HAVE_SPARSE_IRQ
 	select MODULES_USE_ELF_RELA
 	select NEED_SG_DMA_LENGTH
 	select NO_DMA if !MMU && !DMA_COHERENT
diff --git a/arch/sh/include/asm/irq.h b/arch/sh/include/asm/irq.h
index 839551ce398c..5a7b6e324e4c 100644
--- a/arch/sh/include/asm/irq.h
+++ b/arch/sh/include/asm/irq.h
@@ -5,16 +5,7 @@
 #include <linux/cpumask.h>
 #include <asm/machvec.h>
 
-/*
- * Only legacy non-sparseirq platforms have to set a reasonably sane
- * value here. sparseirq platforms allocate their irq_descs on the fly,
- * so will expand automatically based on the number of registered IRQs.
- */
-#ifdef CONFIG_SPARSE_IRQ
 # define NR_IRQS		8
-#else
-# define NR_IRQS		512
-#endif
 
 /*
  * This is a special IRQ number for indicating that no IRQ has been
-- 
2.26.2

[PATCH 2/3] csky: Use SPARSE_IRQ

[Kefeng Wang]

The sparse IRQ framework is preferred, switch over to it,
and Kill MAY_HAVE_SPARSE_IRQ.

Cc: Guo Ren <guoren@kernel.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/csky/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 9d4d898df76b..3d720a577be7 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -69,7 +69,6 @@ config CSKY
 	select HAVE_RSEQ
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
-	select MAY_HAVE_SPARSE_IRQ
 	select MODULES_USE_ELF_RELA if MODULES
 	select OF
 	select OF_EARLY_FLATTREE
@@ -82,6 +81,7 @@ config CSKY
 	select PCI_SYSCALL if PCI
 	select PCI_MSI if PCI
 	select SET_FS
+	select SPARSE_IRQ
 	select TRACE_IRQFLAGS_SUPPORT
 
 config LOCKDEP_SUPPORT
-- 
2.26.2

[PATCH 3/3] genirq: Cleanup Kconfig

[Kefeng Wang]

As the last user of MAY_HAVE_SPARSE_IRQ is gone, kill it, and clean
up the SPARSE_IRQ, covert the help text into comment.

Also move GENERIC_IRQ_MULTI_HANDLER into menu, and change all spaces
to tabs to fix alignment issue.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 kernel/irq/Kconfig | 50 +++++++++++++++++++---------------------------
 1 file changed, 20 insertions(+), 30 deletions(-)

diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index fbc54c2a7f23..aa7d0e3edea6 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -2,13 +2,9 @@
 menu "IRQ subsystem"
 # Options selectable by the architecture code
 
-# Make sparse irq Kconfig switch below available
-config MAY_HAVE_SPARSE_IRQ
-       bool
-
 # Legacy support, required for itanic
 config GENERIC_IRQ_LEGACY
-       bool
+	bool
 
 # Enable the generic irq autoprobe mechanism
 config GENERIC_IRQ_PROBE
@@ -16,15 +12,15 @@ config GENERIC_IRQ_PROBE
 
 # Use the generic /proc/interrupts implementation
 config GENERIC_IRQ_SHOW
-       bool
+	bool
 
 # Print level/edge extra information
 config GENERIC_IRQ_SHOW_LEVEL
-       bool
+	bool
 
 # Supports effective affinity mask
 config GENERIC_IRQ_EFFECTIVE_AFF_MASK
-       bool
+	bool
 
 # Support for delayed migration from interrupt context
 config GENERIC_PENDING_IRQ
@@ -36,7 +32,7 @@ config GENERIC_IRQ_MIGRATION
 
 # Alpha specific irq affinity mechanism
 config AUTO_IRQ_AFFINITY
-       bool
+	bool
 
 # Interrupt injection mechanism
 config GENERIC_IRQ_INJECTION
@@ -44,16 +40,16 @@ config GENERIC_IRQ_INJECTION
 
 # Tasklet based software resend for pending interrupts on enable_irq()
 config HARDIRQS_SW_RESEND
-       bool
+	bool
 
 # Edge style eoi based handler (cell)
 config IRQ_EDGE_EOI_HANDLER
-       bool
+	bool
 
 # Generic configurable interrupt chip implementation
 config GENERIC_IRQ_CHIP
-       bool
-       select IRQ_DOMAIN
+	bool
+	select IRQ_DOMAIN
 
 # Generic irq_domain hw <--> linux irq number translation
 config IRQ_DOMAIN
@@ -103,6 +99,10 @@ config HANDLE_DOMAIN_IRQ
 config IRQ_TIMINGS
 	bool
 
+# Allow to specify the low level IRQ handler at run time.
+config GENERIC_IRQ_MULTI_HANDLER
+	bool
+
 config GENERIC_IRQ_MATRIX_ALLOCATOR
 	bool
 
@@ -111,20 +111,15 @@ config GENERIC_IRQ_RESERVATION_MODE
 
 # Support forced irq threading
 config IRQ_FORCED_THREADING
-       bool
+	bool
 
+# Sparse irq numbering is useful for distro kernels that want
+# to define a high CONFIG_NR_CPUS value but still want to have
+# low kernel memory footprint on smaller machines.
+# Sparse irqs can also be beneficial on NUMA boxes, as they spread
+# out the interrupt descriptors in a more NUMA-friendly way.
 config SPARSE_IRQ
-	bool "Support sparse irq numbering" if MAY_HAVE_SPARSE_IRQ
-	help
-
-	  Sparse irq numbering is useful for distro kernels that want
-	  to define a high CONFIG_NR_CPUS value but still want to have
-	  low kernel memory footprint on smaller machines.
-
-	  ( Sparse irqs can also be beneficial on NUMA boxes, as they spread
-	    out the interrupt descriptors in a more NUMA-friendly way. )
-
-	  If you don't know what to do here, say N.
+	bool
 
 config GENERIC_IRQ_DEBUGFS
 	bool "Expose irq internals in debugfs"
@@ -139,8 +134,3 @@ config GENERIC_IRQ_DEBUGFS
 	  If you don't know what to do here, say N.
 
 endmenu
-
-config GENERIC_IRQ_MULTI_HANDLER
-	bool
-	help
-	  Allow to specify the low level IRQ handler at run time.
-- 
2.26.2

Re: [PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[Guo Ren]

I didn't see the patch delete:
#else /* !CONFIG_SPARSE_IRQ */
struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
        [0 ... NR_IRQS-1] = {
                .handle_irq     = handle_bad_irq,
                .depth          = 1,
                .lock           = __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),
        }
};
...

Flat irq_desc[] is simple and easy for debugging. We do want to del it?

On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
> Most ARCHs support SPARSE_IRQ, and MAY_HAVE_SPARSE_IRQ is useless, and
> only sh and csky select it, but the could use SPARSE_IRQ too, let's
> kill MAY_HAVE_SPARSE_IRQ, also cleanup the kernel/irq/Kconfig a little.
>
> Kefeng Wang (3):
>   sh: Cleanup about SPARSE_IRQ
>   csky: Use SPARSE_IRQ
>   genirq: Cleanup Kconfig
>
>  arch/csky/Kconfig         |  2 +-
>  arch/sh/Kconfig           |  1 -
>  arch/sh/include/asm/irq.h |  9 -------
>  kernel/irq/Kconfig        | 50 ++++++++++++++++-----------------------
>  4 files changed, 21 insertions(+), 41 deletions(-)
>
> --
> 2.26.2
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

Re: [PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[Kefeng Wang]

On 2021/9/27 20:09, Guo Ren wrote:
> I didn't see the patch delete:
> #else /* !CONFIG_SPARSE_IRQ */
> struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
>          [0 ... NR_IRQS-1] = {
>                  .handle_irq     = handle_bad_irq,
>                  .depth          = 1,
>                  .lock           = __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),
>          }
> };
> ...
>
> Flat irq_desc[] is simple and easy for debugging. We do want to del it?

This patches want to kill MAY_HAVE_SPARSE_IRQ,  not !SPARSE_IRQ.

so I won't delete above parts(eg, ARM could use both SPARSE_IRQ and

!SPARSE_IRQ via different config,)

>
> On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>> Most ARCHs support SPARSE_IRQ, and MAY_HAVE_SPARSE_IRQ is useless, and
>> only sh and csky select it, but the could use SPARSE_IRQ too, let's
>> kill MAY_HAVE_SPARSE_IRQ, also cleanup the kernel/irq/Kconfig a little.
>>
>> Kefeng Wang (3):
>>    sh: Cleanup about SPARSE_IRQ
>>    csky: Use SPARSE_IRQ
>>    genirq: Cleanup Kconfig
>>
>>   arch/csky/Kconfig         |  2 +-
>>   arch/sh/Kconfig           |  1 -
>>   arch/sh/include/asm/irq.h |  9 -------
>>   kernel/irq/Kconfig        | 50 ++++++++++++++++-----------------------
>>   4 files changed, 21 insertions(+), 41 deletions(-)
>>
>> --
>> 2.26.2
>>
>

Re: [PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[Guo Ren]

On Mon, Sep 27, 2021 at 8:35 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
>
> On 2021/9/27 20:09, Guo Ren wrote:
> > I didn't see the patch delete:
> > #else /* !CONFIG_SPARSE_IRQ */
> > struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
> >          [0 ... NR_IRQS-1] = {
> >                  .handle_irq     = handle_bad_irq,
> >                  .depth          = 1,
> >                  .lock           = __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),
> >          }
> > };
> > ...
> >
> > Flat irq_desc[] is simple and easy for debugging. We do want to del it?
>
> This patches want to kill MAY_HAVE_SPARSE_IRQ,  not !SPARSE_IRQ.
>
> so I won't delete above parts(eg, ARM could use both SPARSE_IRQ and
>
> !SPARSE_IRQ via different config,)
>
> >
> > On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
> >> Most ARCHs support SPARSE_IRQ, and MAY_HAVE_SPARSE_IRQ is useless, and
> >> only sh and csky select it, but the could use SPARSE_IRQ too, let's
> >> kill MAY_HAVE_SPARSE_IRQ, also cleanup the kernel/irq/Kconfig a little.
Why couldn't choice SPARSE in menuconfig?

> >>
> >> Kefeng Wang (3):
> >>    sh: Cleanup about SPARSE_IRQ
> >>    csky: Use SPARSE_IRQ
> >>    genirq: Cleanup Kconfig
> >>
> >>   arch/csky/Kconfig         |  2 +-
> >>   arch/sh/Kconfig           |  1 -
> >>   arch/sh/include/asm/irq.h |  9 -------
> >>   kernel/irq/Kconfig        | 50 ++++++++++++++++-----------------------
> >>   4 files changed, 21 insertions(+), 41 deletions(-)
> >>
> >> --
> >> 2.26.2
> >>
> >



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

Re: [PATCH 1/3] sh: Cleanup about SPARSE_IRQ

[Geert Uytterhoeven]

Hi Kefeng,

On Mon, Sep 27, 2021 at 10:11 AM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
> After commit 37744feebc08 ("sh: remove sh5 support"), sh always
> enable SPARSE_IRQ, kill unused MAY_HAVE_SPARSE_IRQ and NR_IRQS
> define under !CONFIG_SPARSE_IRQ.
>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Thanks for your patch!

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

One question below...

> --- a/arch/sh/include/asm/irq.h
> +++ b/arch/sh/include/asm/irq.h
> @@ -5,16 +5,7 @@
>  #include <linux/cpumask.h>
>  #include <asm/machvec.h>
>
> -/*
> - * Only legacy non-sparseirq platforms have to set a reasonably sane
> - * value here. sparseirq platforms allocate their irq_descs on the fly,
> - * so will expand automatically based on the number of registered IRQs.
> - */
> -#ifdef CONFIG_SPARSE_IRQ
>  # define NR_IRQS               8
> -#else
> -# define NR_IRQS               512
> -#endif

I'm wondering if we can go even further, and just remove the definition
of NR_IRQS, and fall back to the default in include/asm-generic/irq.h?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 2/3] csky: Use SPARSE_IRQ

[Guo Ren]

On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
> The sparse IRQ framework is preferred, switch over to it,
> and Kill MAY_HAVE_SPARSE_IRQ.
>
> Cc: Guo Ren <guoren@kernel.org>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  arch/csky/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
> index 9d4d898df76b..3d720a577be7 100644
> --- a/arch/csky/Kconfig
> +++ b/arch/csky/Kconfig
> @@ -69,7 +69,6 @@ config CSKY
>         select HAVE_RSEQ
>         select HAVE_STACKPROTECTOR
>         select HAVE_SYSCALL_TRACEPOINTS
> -       select MAY_HAVE_SPARSE_IRQ
>         select MODULES_USE_ELF_RELA if MODULES
>         select OF
>         select OF_EARLY_FLATTREE
> @@ -82,6 +81,7 @@ config CSKY
>         select PCI_SYSCALL if PCI
>         select PCI_MSI if PCI
>         select SET_FS
> +       select SPARSE_IRQ
Most csky platforms use !SPARSE_IRQ, so please remove the above line.

>         select TRACE_IRQFLAGS_SUPPORT
>
>  config LOCKDEP_SUPPORT
> --
> 2.26.2
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

Re: [PATCH 2/3] csky: Use SPARSE_IRQ

[Kefeng Wang]

On 2021/9/28 11:39, Guo Ren wrote:
> On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>> The sparse IRQ framework is preferred, switch over to it,
>> and Kill MAY_HAVE_SPARSE_IRQ.
>>
>> Cc: Guo Ren <guoren@kernel.org>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>> ---
>>   arch/csky/Kconfig | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
>> index 9d4d898df76b..3d720a577be7 100644
>> --- a/arch/csky/Kconfig
>> +++ b/arch/csky/Kconfig
>> @@ -69,7 +69,6 @@ config CSKY
>>          select HAVE_RSEQ
>>          select HAVE_STACKPROTECTOR
>>          select HAVE_SYSCALL_TRACEPOINTS
>> -       select MAY_HAVE_SPARSE_IRQ
>>          select MODULES_USE_ELF_RELA if MODULES
>>          select OF
>>          select OF_EARLY_FLATTREE
>> @@ -82,6 +81,7 @@ config CSKY
>>          select PCI_SYSCALL if PCI
>>          select PCI_MSI if PCI
>>          select SET_FS
>> +       select SPARSE_IRQ
> Most csky platforms use !SPARSE_IRQ, so please remove the above line.
Ok, will drop this.
>
>>          select TRACE_IRQFLAGS_SUPPORT
>>
>>   config LOCKDEP_SUPPORT
>> --
>> 2.26.2
>>
>

Re: [PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[Guo Ren]

On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>
> Most ARCHs support SPARSE_IRQ, and MAY_HAVE_SPARSE_IRQ is useless, and
> only sh and csky select it, but the could use SPARSE_IRQ too, let's
> kill MAY_HAVE_SPARSE_IRQ, also cleanup the kernel/irq/Kconfig a little.
Can you elaborate the reason on why we need to kill MAY_HAVE_SPARSE_IRQ?
What are the benefits after the patch? (As you know we couldn't drop
"!SPARSE_IRQ".)

>
> Kefeng Wang (3):
>   sh: Cleanup about SPARSE_IRQ
>   csky: Use SPARSE_IRQ
>   genirq: Cleanup Kconfig
>
>  arch/csky/Kconfig         |  2 +-
>  arch/sh/Kconfig           |  1 -
>  arch/sh/include/asm/irq.h |  9 -------
>  kernel/irq/Kconfig        | 50 ++++++++++++++++-----------------------
>  4 files changed, 21 insertions(+), 41 deletions(-)
>
> --
> 2.26.2
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

Re: [PATCH 0/3] Cleanup MAY_HAVE_SPARSE_IRQ

[Kefeng Wang]

On 2021/9/28 13:08, Guo Ren wrote:
> On Mon, Sep 27, 2021 at 4:11 PM Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
>> Most ARCHs support SPARSE_IRQ, and MAY_HAVE_SPARSE_IRQ is useless, and
>> only sh and csky select it, but the could use SPARSE_IRQ too, let's
>> kill MAY_HAVE_SPARSE_IRQ, also cleanup the kernel/irq/Kconfig a little.
> Can you elaborate the reason on why we need to kill MAY_HAVE_SPARSE_IRQ?
> What are the benefits after the patch? (As you know we couldn't drop
> "!SPARSE_IRQ".)

If csky want to keep MAY_HAVE_SPARSE_IRQ, then I won't kill it, or no 
one use it,

then cleanup it.