* [PATCH] staging: fbtft: replace empty macro args with identity converter
From: Baker @ 2026-04-12 17:21 UTC (permalink / raw)
To: andy, gregkh; +Cc: dri-devel, linux-fbdev, linux-staging, linux-kernel, Baker
In-Reply-To: <20260412172147.2817-1-mzndmzn@gmail.com>
The define_fbtft_write_reg macro calls 'modifier' as a function.
Passing an empty token as modifier is undefined behavior in C for
fixed-arity macros. Introduce fbtft_no_conv() as an identity
function to replace the empty args in the no-conversion cases.
Signed-off-by: Baker <mzndmzn@gmail.com>
---
drivers/staging/fbtft/fbtft-bus.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
index 30e436ff19e4..8ce263f68ed2 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -11,6 +11,8 @@
*
*****************************************************************************/
+#define fbtft_no_conv(x) (x)
+
#define define_fbtft_write_reg(func, buffer_type, data_type, modifier) \
void func(struct fbtft_par *par, int len, ...) \
{ \
@@ -62,9 +64,9 @@ out: \
} \
EXPORT_SYMBOL(func);
-define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
+define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
define_fbtft_write_reg(fbtft_write_reg16_bus8, __be16, u16, cpu_to_be16)
-define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, )
+define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16)
void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
{
--
2.47.3
^ permalink raw reply related
* [PATCH] staging: fbtft: fix coding style issue in fbtft-bus.c
From: Baker @ 2026-04-12 17:33 UTC (permalink / raw)
To: andy, gregkh; +Cc: dri-devel, linux-fbdev, linux-staging, linux-kernel, Baker
Remove trailing space and comma before closing parenthesis ')' in
define_fbtft_write_reg macro as reported by checkpatch.pl.
Signed-off-by: Baker <mzndmzn@gmail.com>
---
drivers/staging/fbtft/fbtft-bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
index 30e436ff19e4..409770891c54 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -62,9 +62,9 @@ out: \
} \
EXPORT_SYMBOL(func);
-define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
+define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
define_fbtft_write_reg(fbtft_write_reg16_bus8, __be16, u16, cpu_to_be16)
-define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, )
+define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16)
void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
{
--
2.47.3
^ permalink raw reply related
* [PATCH v3] staging: fbtft: replace empty macro args with identity converter
From: Baker @ 2026-04-12 17:33 UTC (permalink / raw)
To: andy, gregkh; +Cc: dri-devel, linux-fbdev, linux-staging, linux-kernel, Baker
In-Reply-To: <20260412173317.3329-1-mzndmzn@gmail.com>
The define_fbtft_write_reg macro calls 'modifier' as a function.
Passing an empty token as modifier is undefined behavior in C for
fixed-arity macros. Introduce fbtft_no_conv() as an identity
function to replace the empty args in the no-conversion cases.
Signed-off-by: Baker <mzndmzn@gmail.com>
---
drivers/staging/fbtft/fbtft-bus.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
index 30e436ff19e4..7f3fd30576ab 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -11,6 +11,8 @@
*
*****************************************************************************/
+#define fbtft_no_conv(x) (x)
+
#define define_fbtft_write_reg(func, buffer_type, data_type, modifier) \
void func(struct fbtft_par *par, int len, ...) \
{ \
@@ -62,9 +64,9 @@ out: \
} \
EXPORT_SYMBOL(func);
-define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
+define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, fbtft_no_conv)
define_fbtft_write_reg(fbtft_write_reg16_bus8, __be16, u16, cpu_to_be16)
-define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, )
+define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, fbtft_no_conv)
void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
{
--
2.47.3
^ permalink raw reply related
* Re: [patch 28/38] mips: Select ARCH_HAS_RANDOM_ENTROPY
From: Maciej W. Rozycki @ 2026-04-13 5:47 UTC (permalink / raw)
To: Thomas Gleixner
Cc: LKML, Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik,
netdev, linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120319.462206386@kernel.org>
On Fri, 10 Apr 2026, Thomas Gleixner wrote:
> The only solution for now is to uninline random_get_entropy(). Fix up all
> other dependencies on the content of asm/timex.h in those files which
> really depend on it.
Oh dear! I'd yet have to fully evaluate the consequences, but offhand
this has clearly turned what compiles to a single CPU instruction on the
vast majority of MIPS platforms into an expensive function call, possibly
also changing the caller from a leaf to a nested function with all the
associated execution penalty. Is there no other way?
Cf. commit 06947aaaf9bf ("MIPS: Implement random_get_entropy with CP0
Random").
Maciej
^ permalink raw reply
* Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter
From: Andy Shevchenko @ 2026-04-13 5:58 UTC (permalink / raw)
To: Baker; +Cc: andy, gregkh, dri-devel, linux-fbdev, linux-staging, linux-kernel
In-Reply-To: <20260412173317.3329-2-mzndmzn@gmail.com>
On Sun, Apr 12, 2026 at 8:33 PM Baker <mzndmzn@gmail.com> wrote:
>
> The define_fbtft_write_reg macro calls 'modifier' as a function.
> Passing an empty token as modifier is undefined behavior in C for
> fixed-arity macros. Introduce fbtft_no_conv() as an identity
> function to replace the empty args in the no-conversion cases.
This trick is used in the kernel (usually for u8). If you really want
to improve, use _Generic() instead.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply
* Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter
From: Greg KH @ 2026-04-13 6:03 UTC (permalink / raw)
To: Andy Shevchenko
Cc: Baker, andy, dri-devel, linux-fbdev, linux-staging, linux-kernel
In-Reply-To: <CAHp75VcdWMvvM-oKTqRACSXSUiVsEh1Ep_82MsJxfbrG4thUdA@mail.gmail.com>
On Mon, Apr 13, 2026 at 08:58:50AM +0300, Andy Shevchenko wrote:
> On Sun, Apr 12, 2026 at 8:33 PM Baker <mzndmzn@gmail.com> wrote:
> >
> > The define_fbtft_write_reg macro calls 'modifier' as a function.
> > Passing an empty token as modifier is undefined behavior in C for
> > fixed-arity macros. Introduce fbtft_no_conv() as an identity
> > function to replace the empty args in the no-conversion cases.
>
> This trick is used in the kernel (usually for u8). If you really want
> to improve, use _Generic() instead.
No, sorry, this code is fine as-is.
greg k-h
^ permalink raw reply
* Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter
From: Andy Shevchenko @ 2026-04-13 6:08 UTC (permalink / raw)
To: Greg KH; +Cc: Baker, andy, dri-devel, linux-fbdev, linux-staging, linux-kernel
In-Reply-To: <2026041338-guiding-concur-3831@gregkh>
On Mon, Apr 13, 2026 at 9:03 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> On Mon, Apr 13, 2026 at 08:58:50AM +0300, Andy Shevchenko wrote:
> > On Sun, Apr 12, 2026 at 8:33 PM Baker <mzndmzn@gmail.com> wrote:
> > >
> > > The define_fbtft_write_reg macro calls 'modifier' as a function.
> > > Passing an empty token as modifier is undefined behavior in C for
> > > fixed-arity macros. Introduce fbtft_no_conv() as an identity
> > > function to replace the empty args in the no-conversion cases.
> >
> > This trick is used in the kernel (usually for u8). If you really want
> > to improve, use _Generic() instead.
>
> No, sorry, this code is fine as-is.
Works for me. I suggested they explore the possibilities, it might be
helpful somewhere else in case of the similar requirements (like in a
new code).
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply
* Re: [PATCH] staging: fbtft: fix spacing before close parenthesis
From: Andy Shevchenko @ 2026-04-13 6:59 UTC (permalink / raw)
To: Arjun Changla
Cc: Greg KH, andy, dri-devel, linux-fbdev, linux-staging,
linux-kernel
In-Reply-To: <CALO5-psPGGxo9bu4Yjs54Sj=Hpq4x4Zgvp6tEY2MzV+utUfGpA@mail.gmail.com>
On Mon, Apr 13, 2026 at 9:58 AM Arjun Changla <arjunchangla7@gmail.com> wrote:
>
>
>
> On Thu, 18 Dec 2025 at 11:50, Greg KH <gregkh@linuxfoundation.org> wrote:
>>
>> On Thu, Dec 18, 2025 at 06:14:06AM +0000, Arjun Changla wrote:
>> > Fix checkpatch error "space prohibited before that close parenthesis"
>> > on line 65 by removing the extra space.
>> >
>> > Signed-off-by: Arjun Changla <arjunchangla7@gmail.com>
>> > ---
>> > drivers/staging/fbtft/fbtft-bus.c | 2 +-
>> > 1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
>> > index 30e436ff19e4..2f7c891177fb 100644
>> > --- a/drivers/staging/fbtft/fbtft-bus.c
>> > +++ b/drivers/staging/fbtft/fbtft-bus.c
>> > @@ -62,7 +62,7 @@ out: \
>> > } \
>> > EXPORT_SYMBOL(func);
>> >
>> > -define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
>> > +define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
>>
>> But you just changed the function definition, does this still work now?
>> If so, how?
>>
>> confused,
>>
>> greg k-h
>
>
> Hi Greg,
>
> Thank you for the review. The change only removes extra spacing in
> the function parameter - no functional changes were made.
>
> Before:
> const struct ia_css_output1_configuration *from ,
>
> After:
> const struct ia_css_output1_configuration *from,
>
> I verified the module builds successfully with no errors:
> make M=drivers/staging/fbtft
What are you talking about?
The original patch we are discussing is totally wrong. Please, compile
the code before submitting.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply
* Re: [PATCH] staging: fbtft: Use %pe format specifier for error pointers
From: Andy Shevchenko @ 2026-04-13 7:03 UTC (permalink / raw)
To: Mahad Ibrahim
Cc: Andy Shevchenko, Greg Kroah-Hartman, Shuah Khan,
linux-kernel-mentees, dri-devel, linux-fbdev, linux-staging,
linux-kernel
In-Reply-To: <20260412144552.18493-1-mahad.ibrahim.dev@gmail.com>
On Sun, Apr 12, 2026 at 5:46 PM Mahad Ibrahim
<mahad.ibrahim.dev@gmail.com> wrote:
>
> The %pe format specifier resolves error pointers to their symbolic
> representation. Previously %ld with PTR_ERR() was being used, %pe is a
> better alternative.
>
> Fixes the following coccinelle warnings reported by coccicheck:
> WARNING: Consider using %pe to print PTR_ERR()
>
> Testing: I do not own the hardware, therefore I could not perform
> hardware testing. Compile tested only.
I don't think it makes any difference for this driver. But I am not
objecting to the change. Up to Greg if he wants to apply or not.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply
* Re: [PATCH 1/8] hv: Select CONFIG_SYSFB only for CONFIG_HYPERV_VMBUS
From: Thomas Zimmermann @ 2026-04-13 7:17 UTC (permalink / raw)
To: Saurabh Singh Sengar, javierm@redhat.com, arnd@arndb.de,
ardb@kernel.org, ilias.apalodimas@linaro.org,
chenhuacai@kernel.org, kernel@xen0n.name,
maarten.lankhorst@linux.intel.com, mripard@kernel.org,
airlied@gmail.com, simona@ffwll.ch, KY Srinivasan, Haiyang Zhang,
wei.liu@kernel.org, Dexuan Cui, Long Li, deller@gmx.de
Cc: linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linux-efi@vger.kernel.org, linux-riscv@lists.infradead.org,
dri-devel@lists.freedesktop.org, linux-hyperv@vger.kernel.org,
linux-fbdev@vger.kernel.org, Michael Kelley, Saurabh Sengar,
stable@vger.kernel.org
In-Reply-To: <KUZP153MB14449BBE44CBAEEA7621A4A0BE51A@KUZP153MB1444.APCP153.PROD.OUTLOOK.COM>
Hi
Am 02.04.26 um 12:50 schrieb Saurabh Singh Sengar:
>> Hyperv's sysfb access only exists in the VMBUS support. Therefore only select
>> CONFIG_SYSFB for CONFIG_HYPERV_VMBUS. Avoids sysfb code on systems
>> that don't need it.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Fixes: 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB for Hyper-V
>> guests")
>> Cc: Michael Kelley <mhklinux@outlook.com>
>> Cc: Saurabh Sengar <ssengar@linux.microsoft.com>
>> Cc: Wei Liu <wei.liu@kernel.org>
>> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
>> Cc: Haiyang Zhang <haiyangz@microsoft.com>
>> Cc: Dexuan Cui <decui@microsoft.com>
>> Cc: Long Li <longli@microsoft.com>
>> Cc: linux-hyperv@vger.kernel.org
>> Cc: <stable@vger.kernel.org> # v6.16+
>> ---
>> drivers/hv/Kconfig | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig index
>> 7937ac0cbd0f..2d0b3fcb0ff8 100644
>> --- a/drivers/hv/Kconfig
>> +++ b/drivers/hv/Kconfig
>> @@ -9,7 +9,6 @@ config HYPERV
>> select PARAVIRT
>> select X86_HV_CALLBACK_VECTOR if X86
>> select OF_EARLY_FLATTREE if OF
>> - select SYSFB if EFI && !HYPERV_VTL_MODE
>> select IRQ_MSI_LIB if X86
>> help
>> Select this option to run Linux as a Hyper-V client operating @@ -62,6
>> +61,7 @@ config HYPERV_VMBUS
>> tristate "Microsoft Hyper-V VMBus driver"
>> depends on HYPERV
>> default HYPERV
>> + select SYSFB if EFI && !HYPERV_VTL_MODE
>> help
>> Select this option to enable Hyper-V Vmbus driver.
>>
>> --
>> 2.53.0
> Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
This fix is independent from the rest of the series. Do you want to
merge it or can I take it into DRM trees?
Best regards
Thomas
>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
^ permalink raw reply
* Re: [PATCH] staging: fbtft: improve TODO comment clarity
From: Andy Shevchenko @ 2026-04-13 7:27 UTC (permalink / raw)
To: Chandra Mouli Baskaran
Cc: gregkh, andy, linux-staging, linux-fbdev, dri-devel, linux-kernel
In-Reply-To: <20260411152220.89174-1-bcmouli2006@gmail.com>
On Sat, Apr 11, 2026 at 6:26 PM Chandra Mouli Baskaran
<bcmouli2006@gmail.com> wrote:
>
> From: Chandra Mouli <bcmouli2006@gmail.com>
>
> Clarify the TODO comment in fbtft_ops_damage_range() to
> better describe that the current implementation updates
> the entire displayinstead of only the modified region.
Please, spellcheck the commit messages...
There was an attempt to improve that. Do you have HW to test?
> - /* TODO: only mark changed area update all for now */
> + /* TODO: Optimize to update only the modified region instead
> + * of refreshing the entire display.
> + */
/*
* The style of multi-line comment is still wrong. You
* may use this example.
*/
And also note:
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/tree/drivers/staging/fbtft/README?h=staging-next
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply
* Re: [PATCH] staging: fbtft: Use %pe format specifier for error pointers
From: Dan Carpenter @ 2026-04-13 7:49 UTC (permalink / raw)
To: Andy Shevchenko
Cc: Mahad Ibrahim, Andy Shevchenko, Greg Kroah-Hartman, Shuah Khan,
linux-kernel-mentees, dri-devel, linux-fbdev, linux-staging,
linux-kernel
In-Reply-To: <CAHp75Vdu6pih=NqkYT0CR_oLyr3YgNKBeqYM3+naqVp52UCgVw@mail.gmail.com>
On Mon, Apr 13, 2026 at 10:03:58AM +0300, Andy Shevchenko wrote:
> On Sun, Apr 12, 2026 at 5:46 PM Mahad Ibrahim
> <mahad.ibrahim.dev@gmail.com> wrote:
> >
> > The %pe format specifier resolves error pointers to their symbolic
> > representation. Previously %ld with PTR_ERR() was being used, %pe is a
> > better alternative.
> >
> > Fixes the following coccinelle warnings reported by coccicheck:
> > WARNING: Consider using %pe to print PTR_ERR()
> >
> > Testing: I do not own the hardware, therefore I could not perform
> > hardware testing. Compile tested only.
>
> I don't think it makes any difference for this driver. But I am not
> objecting to the change. Up to Greg if he wants to apply or not.
I always like these changes. I wish that there were an equivalent
%e which printed error codes that weren't stored in an error pointer.
KTODO: introduce a %e type format thing which prints error codes
regards,
dan carpenter
^ permalink raw reply
* Re: [PATCH] staging: fbtft: Use %pe format specifier for error pointers
From: Andy Shevchenko @ 2026-04-13 7:53 UTC (permalink / raw)
To: Dan Carpenter
Cc: Mahad Ibrahim, Andy Shevchenko, Greg Kroah-Hartman, Shuah Khan,
linux-kernel-mentees, dri-devel, linux-fbdev, linux-staging,
linux-kernel
In-Reply-To: <adygIkRhnsGv-LwM@stanley.mountain>
On Mon, Apr 13, 2026 at 10:49 AM Dan Carpenter <error27@gmail.com> wrote:
> On Mon, Apr 13, 2026 at 10:03:58AM +0300, Andy Shevchenko wrote:
> > On Sun, Apr 12, 2026 at 5:46 PM Mahad Ibrahim
> > <mahad.ibrahim.dev@gmail.com> wrote:
...
> I always like these changes. I wish that there were an equivalent
> %e which printed error codes that weren't stored in an error pointer.
>
> KTODO: introduce a %e type format thing which prints error codes
Never happens until it becomes a C standard.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply
* (no subject)
From: Harry Yoo (Oracle) @ 2026-04-13 7:58 UTC (permalink / raw)
To: Thomas Gleixner
Cc: LKML, Vlastimil Babka, linux-mm, Arnd Bergmann, x86, Lu Baolu,
iommu, Michael Grzeschik, netdev, linux-wireless, Herbert Xu,
linux-crypto, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux, Hao Li, Christoph Lameter, David Rientjes,
Roman Gushchin, Shengming Hu
Bcc:
Subject: Re: [patch 14/38] slub: Use prandom instead of get_cycles()
Reply-To:
In-Reply-To: <20260410120318.525653921@kernel.org>
On Fri, Apr 10, 2026 at 02:19:37PM +0200, Thomas Gleixner wrote:
> The decision whether to scan remote nodes is based on a 'random' number
> retrieved via get_cycles(). get_cycles() is about to be removed.
>
> There is already prandom state in the code, so use that instead.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Vlastimil Babka <vbabka@kernel.org>
> Cc: linux-mm@kvack.org
> ---
Acked-by: Harry Yoo (Oracle) <harry@kernel.org>
Is this for this merge window?
This may conflict with upcoming changes on freelist shuffling [1]
(not queued for slab/for-next yet though), but it should be easy to
resolve.
[Cc'ing Shengming and SLAB ALLOCATOR folks]
[1] https://lore.kernel.org/linux-mm/20260409204352095kKWVYKtZImN59ybO6iRNj@zte.com.cn
--
Cheers,
Harry / Hyeonggon
> mm/slub.c | 37 +++++++++++++++++++++++--------------
> 1 file changed, 23 insertions(+), 14 deletions(-)
>
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3302,6 +3302,25 @@ static inline struct slab *alloc_slab_pa
> return slab;
> }
>
> +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
> +static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
> +
> +static unsigned int slab_get_prandom_state(unsigned int limit)
> +{
> + struct rnd_state *state;
> + unsigned int res;
> +
> + /*
> + * An interrupt or NMI handler might interrupt and change
> + * the state in the middle, but that's safe.
> + */
> + state = &get_cpu_var(slab_rnd_state);
> + res = prandom_u32_state(state) % limit;
> + put_cpu_var(slab_rnd_state);
> + return res;
> +}
> +#endif
> +
> #ifdef CONFIG_SLAB_FREELIST_RANDOM
> /* Pre-initialize the random sequence cache */
> static int init_cache_random_seq(struct kmem_cache *s)
> @@ -3365,8 +3384,6 @@ static void *next_freelist_entry(struct
> return (char *)start + idx;
> }
>
> -static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
> -
> /* Shuffle the single linked freelist based on a random pre-computed sequence */
> static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab,
> bool allow_spin)
> @@ -3383,15 +3400,7 @@ static bool shuffle_freelist(struct kmem
> if (allow_spin) {
> pos = get_random_u32_below(freelist_count);
> } else {
> - struct rnd_state *state;
> -
> - /*
> - * An interrupt or NMI handler might interrupt and change
> - * the state in the middle, but that's safe.
> - */
> - state = &get_cpu_var(slab_rnd_state);
> - pos = prandom_u32_state(state) % freelist_count;
> - put_cpu_var(slab_rnd_state);
> + pos = slab_get_prandom_state(freelist_count);
> }
>
> page_limit = slab->objects * s->size;
> @@ -3882,7 +3891,7 @@ static void *get_from_any_partial(struct
> * with available objects.
> */
> if (!s->remote_node_defrag_ratio ||
> - get_cycles() % 1024 > s->remote_node_defrag_ratio)
> + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
> return NULL;
>
> do {
> @@ -7102,7 +7111,7 @@ static unsigned int
>
> /* see get_from_any_partial() for the defrag ratio description */
> if (!s->remote_node_defrag_ratio ||
> - get_cycles() % 1024 > s->remote_node_defrag_ratio)
> + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
> return 0;
>
> do {
> @@ -8421,7 +8430,7 @@ void __init kmem_cache_init_late(void)
> flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU,
> 0);
> WARN_ON(!flushwq);
> -#ifdef CONFIG_SLAB_FREELIST_RANDOM
> +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
> prandom_init_once(&slab_rnd_state);
> #endif
> }
>
>
^ permalink raw reply
* RE: [EXTERNAL] Re: [PATCH 1/8] hv: Select CONFIG_SYSFB only for CONFIG_HYPERV_VMBUS
From: Saurabh Singh Sengar @ 2026-04-13 8:22 UTC (permalink / raw)
To: Thomas Zimmermann, javierm@redhat.com, arnd@arndb.de,
ardb@kernel.org, ilias.apalodimas@linaro.org,
chenhuacai@kernel.org, kernel@xen0n.name,
maarten.lankhorst@linux.intel.com, mripard@kernel.org,
airlied@gmail.com, simona@ffwll.ch, KY Srinivasan, Haiyang Zhang,
wei.liu@kernel.org, Dexuan Cui, Long Li, deller@gmx.de
Cc: linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linux-efi@vger.kernel.org, linux-riscv@lists.infradead.org,
dri-devel@lists.freedesktop.org, linux-hyperv@vger.kernel.org,
linux-fbdev@vger.kernel.org, Michael Kelley, Saurabh Sengar,
stable@vger.kernel.org, Wei Liu
In-Reply-To: <2fe8ce91-2dc5-4cf2-b7cf-d495e5cff14b@suse.de>
> Hi
>
> Am 02.04.26 um 12:50 schrieb Saurabh Singh Sengar:
> >> Hyperv's sysfb access only exists in the VMBUS support. Therefore
> >> only select CONFIG_SYSFB for CONFIG_HYPERV_VMBUS. Avoids sysfb code
> >> on systems that don't need it.
> >>
> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >> Fixes: 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB for
> >> Hyper-V
> >> guests")
> >> Cc: Michael Kelley <mhklinux@outlook.com>
> >> Cc: Saurabh Sengar <ssengar@linux.microsoft.com>
> >> Cc: Wei Liu <wei.liu@kernel.org>
> >> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> >> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> >> Cc: Dexuan Cui <decui@microsoft.com>
> >> Cc: Long Li <longli@microsoft.com>
> >> Cc: linux-hyperv@vger.kernel.org
> >> Cc: <stable@vger.kernel.org> # v6.16+
> >> ---
> >> drivers/hv/Kconfig | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig index
> >> 7937ac0cbd0f..2d0b3fcb0ff8 100644
> >> --- a/drivers/hv/Kconfig
> >> +++ b/drivers/hv/Kconfig
> >> @@ -9,7 +9,6 @@ config HYPERV
> >> select PARAVIRT
> >> select X86_HV_CALLBACK_VECTOR if X86
> >> select OF_EARLY_FLATTREE if OF
> >> - select SYSFB if EFI && !HYPERV_VTL_MODE
> >> select IRQ_MSI_LIB if X86
> >> help
> >> Select this option to run Linux as a Hyper-V client operating @@
> >> -62,6
> >> +61,7 @@ config HYPERV_VMBUS
> >> tristate "Microsoft Hyper-V VMBus driver"
> >> depends on HYPERV
> >> default HYPERV
> >> + select SYSFB if EFI && !HYPERV_VTL_MODE
> >> help
> >> Select this option to enable Hyper-V Vmbus driver.
> >>
> >> --
> >> 2.53.0
> > Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
>
> This fix is independent from the rest of the series. Do you want to merge it or
> can I take it into DRM trees?
Please feel free to take it via DRM tree.
CC : Wei Liu
- Saurabh
^ permalink raw reply
* Re: [patch 14/38] slub: Use prandom instead of get_cycles()
From: Vlastimil Babka (SUSE) @ 2026-04-13 9:00 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: linux-mm, Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik,
netdev, linux-wireless, Herbert Xu, linux-crypto, David Woodhouse,
Bernie Thompson, linux-fbdev, Theodore Tso, linux-ext4,
Andrew Morton, Uladzislau Rezki, Marco Elver, Dmitry Vyukov,
kasan-dev, Andrey Ryabinin, Thomas Sailer, linux-hams,
Jason A. Donenfeld, Richard Henderson, linux-alpha, Russell King,
linux-arm-kernel, Catalin Marinas, Huacai Chen, loongarch,
Geert Uytterhoeven, linux-m68k, Dinh Nguyen, Jonas Bonn,
linux-openrisc, Helge Deller, linux-parisc, Michael Ellerman,
linuxppc-dev, Paul Walmsley, linux-riscv, Heiko Carstens,
linux-s390, David S. Miller, sparclinux, Harry Yoo (Oracle),
Hao Li
In-Reply-To: <20260410120318.525653921@kernel.org>
On 4/10/26 14:19, Thomas Gleixner wrote:
> The decision whether to scan remote nodes is based on a 'random' number
> retrieved via get_cycles(). get_cycles() is about to be removed.
>
> There is already prandom state in the code, so use that instead.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Vlastimil Babka <vbabka@kernel.org>
> Cc: linux-mm@kvack.org
LGTM.
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
^ permalink raw reply
* Re: [patch 14/38] slub: Use prandom instead of get_cycles()
From: Harry Yoo (Oracle) @ 2026-04-13 9:07 UTC (permalink / raw)
To: Thomas Gleixner
Cc: LKML, Vlastimil Babka, linux-mm, Arnd Bergmann, x86, Lu Baolu,
iommu, Michael Grzeschik, netdev, linux-wireless, Herbert Xu,
linux-crypto, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux, Hao Li, Christoph Lameter, David Rientjes,
Roman Gushchin, Shengming Hu
In-Reply-To: <20260410120318.525653921@kernel.org>
[Resending after fixing broken email headers]
On Fri, Apr 10, 2026 at 02:19:37PM +0200, Thomas Gleixner wrote:
> The decision whether to scan remote nodes is based on a 'random' number
> retrieved via get_cycles(). get_cycles() is about to be removed.
>
> There is already prandom state in the code, so use that instead.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Vlastimil Babka <vbabka@kernel.org>
> Cc: linux-mm@kvack.org
> ---
Acked-by: Harry Yoo (Oracle) <harry@kernel.org>
Is this for this merge window?
This may conflict with upcoming changes on freelist shuffling [1]
(not queued for slab/for-next yet though), but it should be easy to
resolve.
[Cc'ing Shengming and SLAB ALLOCATOR folks]
[1] https://lore.kernel.org/linux-mm/20260409204352095kKWVYKtZImN59ybO6iRNj@zte.com.cn
--
Cheers,
Harry / Hyeonggon
> mm/slub.c | 37 +++++++++++++++++++++++--------------
> 1 file changed, 23 insertions(+), 14 deletions(-)
>
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3302,6 +3302,25 @@ static inline struct slab *alloc_slab_pa
> return slab;
> }
>
> +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
> +static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
> +
> +static unsigned int slab_get_prandom_state(unsigned int limit)
> +{
> + struct rnd_state *state;
> + unsigned int res;
> +
> + /*
> + * An interrupt or NMI handler might interrupt and change
> + * the state in the middle, but that's safe.
> + */
> + state = &get_cpu_var(slab_rnd_state);
> + res = prandom_u32_state(state) % limit;
> + put_cpu_var(slab_rnd_state);
> + return res;
> +}
> +#endif
> +
> #ifdef CONFIG_SLAB_FREELIST_RANDOM
> /* Pre-initialize the random sequence cache */
> static int init_cache_random_seq(struct kmem_cache *s)
> @@ -3365,8 +3384,6 @@ static void *next_freelist_entry(struct
> return (char *)start + idx;
> }
>
> -static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
> -
> /* Shuffle the single linked freelist based on a random pre-computed sequence */
> static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab,
> bool allow_spin)
> @@ -3383,15 +3400,7 @@ static bool shuffle_freelist(struct kmem
> if (allow_spin) {
> pos = get_random_u32_below(freelist_count);
> } else {
> - struct rnd_state *state;
> -
> - /*
> - * An interrupt or NMI handler might interrupt and change
> - * the state in the middle, but that's safe.
> - */
> - state = &get_cpu_var(slab_rnd_state);
> - pos = prandom_u32_state(state) % freelist_count;
> - put_cpu_var(slab_rnd_state);
> + pos = slab_get_prandom_state(freelist_count);
> }
>
> page_limit = slab->objects * s->size;
> @@ -3882,7 +3891,7 @@ static void *get_from_any_partial(struct
> * with available objects.
> */
> if (!s->remote_node_defrag_ratio ||
> - get_cycles() % 1024 > s->remote_node_defrag_ratio)
> + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
> return NULL;
>
> do {
> @@ -7102,7 +7111,7 @@ static unsigned int
>
> /* see get_from_any_partial() for the defrag ratio description */
> if (!s->remote_node_defrag_ratio ||
> - get_cycles() % 1024 > s->remote_node_defrag_ratio)
> + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
> return 0;
>
> do {
> @@ -8421,7 +8430,7 @@ void __init kmem_cache_init_late(void)
> flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU,
> 0);
> WARN_ON(!flushwq);
> -#ifdef CONFIG_SLAB_FREELIST_RANDOM
> +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
> prandom_init_once(&slab_rnd_state);
> #endif
> }
>
>
^ permalink raw reply
* Re: [patch 07/38] treewide: Consolidate cycles_t
From: Ojaswin Mujoo @ 2026-04-13 9:15 UTC (permalink / raw)
To: Thomas Gleixner
Cc: LKML, Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik,
netdev, linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120318.045532623@kernel.org>
On Fri, Apr 10, 2026 at 02:19:03PM +0200, Thomas Gleixner wrote:
> Most architectures define cycles_t as unsigned long execpt:
>
> - x86 requires it to be 64-bit independent of the 32-bit/64-bit build.
>
> - parisc and mips define it as unsigned int
>
> parisc has no real reason to do so as there are only a few usage sites
> which either expand it to a 64-bit value or utilize only the lower
> 32bits.
>
> mips has no real requirement either.
>
> Move the typedef to types.h and provide a config switch to enforce the
> 64-bit type for x86.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> arch/Kconfig | 4 ++++
> arch/alpha/include/asm/timex.h | 3 ---
> arch/arm/include/asm/timex.h | 1 -
> arch/loongarch/include/asm/timex.h | 2 --
> arch/m68k/include/asm/timex.h | 2 --
> arch/mips/include/asm/timex.h | 2 --
> arch/nios2/include/asm/timex.h | 2 --
> arch/parisc/include/asm/timex.h | 2 --
> arch/powerpc/include/asm/timex.h | 4 +---
> arch/riscv/include/asm/timex.h | 2 --
> arch/s390/include/asm/timex.h | 2 --
> arch/sparc/include/asm/timex_64.h | 1 -
> arch/x86/Kconfig | 1 +
> arch/x86/include/asm/tsc.h | 2 --
> include/asm-generic/timex.h | 1 -
> include/linux/types.h | 6 ++++++
> 16 files changed, 12 insertions(+), 25 deletions(-)
>
<...>
> --- a/arch/powerpc/include/asm/timex.h
> +++ b/arch/powerpc/include/asm/timex.h
> @@ -11,9 +11,7 @@
> #include <asm/cputable.h>
> #include <asm/vdso/timebase.h>
>
> -typedef unsigned long cycles_t;
> -
> -static inline cycles_t get_cycles(void)
> +ostatic inline cycles_t get_cycles(void)
Hi Thomas, I'm in middle of testing this series on powerpc. In the meantime I
noticed that there's probably a small typo here (althrough this is fixed
later)
Regards,
ojaswin
> {
> return mftb();
> }
^ permalink raw reply
* Re: [patch 14/38] slub: Use prandom instead of get_cycles()
From: hu.shengming @ 2026-04-13 13:02 UTC (permalink / raw)
To: harry
Cc: tglx, linux-kernel, vbabka, linux-mm, arnd, x86, baolu.lu, iommu,
m.grzeschik, netdev, linux-wireless, herbert, linux-crypto, dwmw2,
bernie, linux-fbdev, tytso, linux-ext4, akpm, urezki, elver,
dvyukov, kasan-dev, ryabinin.a.a, t.sailer, linux-hams, Jason,
richard.henderson, linux-alpha, linux, linux-arm-kernel,
catalin.marinas, chenhuacai, loongarch, geert, linux-m68k,
dinguyen, jonas, linux-openrisc, deller, linux-parisc, mpe,
linuxppc-dev, pjw, linux-riscv, hca, linux-s390, davem,
sparclinux, hao.li, cl, rientjes, roman.gushchin
In-Reply-To: <adyyNeVTkXQlnh_2@hyeyoo>
Harry wrote:
> [Resending after fixing broken email headers]
>
> On Fri, Apr 10, 2026 at 02:19:37PM +0200, Thomas Gleixner wrote:
> > The decision whether to scan remote nodes is based on a 'random' number
> > retrieved via get_cycles(). get_cycles() is about to be removed.
> >
> > There is already prandom state in the code, so use that instead.
> >
> > Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> > Cc: Vlastimil Babka <vbabka@kernel.org>
> > Cc: linux-mm@kvack.org
> > ---
>
> Acked-by: Harry Yoo (Oracle) <harry@kernel.org>
>
> Is this for this merge window?
>
> This may conflict with upcoming changes on freelist shuffling [1]
> (not queued for slab/for-next yet though), but it should be easy to
> resolve.
>
Hi Harry,
Would you like me to wait for this patch to land linux-next and then
rebase and send v6 on top?
Thanks,
--
With Best Regards,
Shengming
> [Cc'ing Shengming and SLAB ALLOCATOR folks]
> [1] https://lore.kernel.org/linux-mm/20260409204352095kKWVYKtZImN59ybO6iRNj@zte.com.cn
>
> --
> Cheers,
> Harry / Hyeonggon
>
> > mm/slub.c | 37 +++++++++++++++++++++++--------------
> > 1 file changed, 23 insertions(+), 14 deletions(-)
> >
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -3302,6 +3302,25 @@ static inline struct slab *alloc_slab_pa
> > return slab;
> > }
> >
> > +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
> > +static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
> > +
> > +static unsigned int slab_get_prandom_state(unsigned int limit)
> > +{
> > + struct rnd_state *state;
> > + unsigned int res;
> > +
> > + /*
> > + * An interrupt or NMI handler might interrupt and change
> > + * the state in the middle, but that's safe.
> > + */
> > + state = &get_cpu_var(slab_rnd_state);
> > + res = prandom_u32_state(state) % limit;
> > + put_cpu_var(slab_rnd_state);
> > + return res;
> > +}
> > +#endif
> > +
> > #ifdef CONFIG_SLAB_FREELIST_RANDOM
> > /* Pre-initialize the random sequence cache */
> > static int init_cache_random_seq(struct kmem_cache *s)
> > @@ -3365,8 +3384,6 @@ static void *next_freelist_entry(struct
> > return (char *)start + idx;
> > }
> >
> > -static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
> > -
> > /* Shuffle the single linked freelist based on a random pre-computed sequence */
> > static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab,
> > bool allow_spin)
> > @@ -3383,15 +3400,7 @@ static bool shuffle_freelist(struct kmem
> > if (allow_spin) {
> > pos = get_random_u32_below(freelist_count);
> > } else {
> > - struct rnd_state *state;
> > -
> > - /*
> > - * An interrupt or NMI handler might interrupt and change
> > - * the state in the middle, but that's safe.
> > - */
> > - state = &get_cpu_var(slab_rnd_state);
> > - pos = prandom_u32_state(state) % freelist_count;
> > - put_cpu_var(slab_rnd_state);
> > + pos = slab_get_prandom_state(freelist_count);
> > }
> >
> > page_limit = slab->objects * s->size;
> > @@ -3882,7 +3891,7 @@ static void *get_from_any_partial(struct
> > * with available objects.
> > */
> > if (!s->remote_node_defrag_ratio ||
> > - get_cycles() % 1024 > s->remote_node_defrag_ratio)
> > + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
> > return NULL;
> >
> > do {
> > @@ -7102,7 +7111,7 @@ static unsigned int
> >
> > /* see get_from_any_partial() for the defrag ratio description */
> > if (!s->remote_node_defrag_ratio ||
> > - get_cycles() % 1024 > s->remote_node_defrag_ratio)
> > + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
> > return 0;
> >
> > do {
> > @@ -8421,7 +8430,7 @@ void __init kmem_cache_init_late(void)
> > flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU,
> > 0);
> > WARN_ON(!flushwq);
> > -#ifdef CONFIG_SLAB_FREELIST_RANDOM
> > +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
> > prandom_init_once(&slab_rnd_state);
> > #endif
> > }
> >
> >
^ permalink raw reply
* Re: [patch 14/38] slub: Use prandom instead of get_cycles()
From: Vlastimil Babka (SUSE) @ 2026-04-13 13:45 UTC (permalink / raw)
To: hu.shengming, harry
Cc: tglx, linux-kernel, linux-mm, arnd, x86, baolu.lu, iommu,
m.grzeschik, netdev, linux-wireless, herbert, linux-crypto, dwmw2,
bernie, linux-fbdev, tytso, linux-ext4, akpm, urezki, elver,
dvyukov, kasan-dev, ryabinin.a.a, t.sailer, linux-hams, Jason,
richard.henderson, linux-alpha, linux, linux-arm-kernel,
catalin.marinas, chenhuacai, loongarch, geert, linux-m68k,
dinguyen, jonas, linux-openrisc, deller, linux-parisc, mpe,
linuxppc-dev, pjw, linux-riscv, hca, linux-s390, davem,
sparclinux, hao.li, cl, rientjes, roman.gushchin
In-Reply-To: <20260413210252672ZfdcegJLJtyvlYdFAUBlr@zte.com.cn>
On 4/13/26 15:02, hu.shengming@zte.com.cn wrote:
> Harry wrote:
>> [Resending after fixing broken email headers]
>>
>> On Fri, Apr 10, 2026 at 02:19:37PM +0200, Thomas Gleixner wrote:
>> > The decision whether to scan remote nodes is based on a 'random' number
>> > retrieved via get_cycles(). get_cycles() is about to be removed.
>> >
>> > There is already prandom state in the code, so use that instead.
>> >
>> > Signed-off-by: Thomas Gleixner <tglx@kernel.org>
>> > Cc: Vlastimil Babka <vbabka@kernel.org>
>> > Cc: linux-mm@kvack.org
>> > ---
>>
>> Acked-by: Harry Yoo (Oracle) <harry@kernel.org>
>>
>> Is this for this merge window?
I'd say it's not intended for 7.1 as it's not in -next and v1 was posted
just before the merge window.
>> This may conflict with upcoming changes on freelist shuffling [1]
>> (not queued for slab/for-next yet though), but it should be easy to
>> resolve.
Indeed, it's a simple conflict.
>
> Hi Harry,
>
> Would you like me to wait for this patch to land linux-next and then
> rebase and send v6 on top?
Just send it now based same as previously so we can finish the reviews, and
we'll deal with it after rc1.
^ permalink raw reply
* Re: [patch 32/38] powerpc/spufs: Use mftb() directly
From: Arnd Bergmann @ 2026-04-13 14:43 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Michael Ellerman, linuxppc-dev, x86, Baolu Lu, iommu,
Michael Grzeschik, Netdev, linux-wireless, Herbert Xu,
linux-crypto, Vlastimil Babka (SUSE), linux-mm, David Woodhouse,
Bernie Thompson, linux-fbdev, Theodore Ts'o, linux-ext4,
Andrew Morton, Uladzislau Rezki (Sony), Marco Elver,
Dmitry Vyukov, kasan-dev, Andrey Ryabinin, Thomas Sailer,
linux-hams, Jason A . Donenfeld, Richard Henderson, linux-alpha,
Russell King, linux-arm-kernel, Catalin Marinas, Huacai Chen,
loongarch, Geert Uytterhoeven, linux-m68k, Dinh Nguyen,
Jonas Bonn, linux-openrisc@vger.kernel.org, Helge Deller,
linux-parisc, Paul Walmsley, linux-riscv, Heiko Carstens,
linux-s390, David S . Miller, sparclinux
In-Reply-To: <20260410120319.723429844@kernel.org>
On Fri, Apr 10, 2026, at 14:21, Thomas Gleixner wrote:
> There is no reason to indirect via get_cycles(), which is about to be
> removed.
>
> Use mftb() directly.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: linuxppc-dev@lists.ozlabs.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
^ permalink raw reply
* Re: [patch 38/38] treewide: Remove asm/timex.h includes from generic code
From: Arnd Bergmann @ 2026-04-13 14:45 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: x86, Baolu Lu, iommu, Michael Grzeschik, Netdev, linux-wireless,
Herbert Xu, linux-crypto, Vlastimil Babka (SUSE), linux-mm,
David Woodhouse, Bernie Thompson, linux-fbdev, Theodore Ts'o,
linux-ext4, Andrew Morton, Uladzislau Rezki (Sony), Marco Elver,
Dmitry Vyukov, kasan-dev, Andrey Ryabinin, Thomas Sailer,
linux-hams, Jason A . Donenfeld, Richard Henderson, linux-alpha,
Russell King, linux-arm-kernel, Catalin Marinas, Huacai Chen,
loongarch, Geert Uytterhoeven, linux-m68k, Dinh Nguyen,
Jonas Bonn, linux-openrisc@vger.kernel.org, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S . Miller,
sparclinux
In-Reply-To: <20260410120320.163559629@kernel.org>
On Fri, Apr 10, 2026, at 14:21, Thomas Gleixner wrote:
> asm/timex.h does not provide any functionality for non-architecture code
> anymore.
>
> Remove the asm-generic fallback and all references in include and source
> files along with the random_get_entropy() #ifdeffery in timex.h.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> include/asm-generic/Kbuild | 1 -
> include/asm-generic/timex.h | 15 ---------------
> include/linux/random.h | 3 +++
> include/linux/timex.h | 26 --------------------------
Acked-by: Arnd Bergmann <arnd@arndb.de>
^ permalink raw reply
* Re: [patch 17/38] ext4: Replace get_cycles() usage with ktime_get()
From: Arnd Bergmann @ 2026-04-13 14:46 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Theodore Ts'o, linux-ext4, x86, Baolu Lu, iommu,
Michael Grzeschik, Netdev, linux-wireless, Herbert Xu,
linux-crypto, Vlastimil Babka (SUSE), linux-mm, David Woodhouse,
Bernie Thompson, linux-fbdev, Andrew Morton,
Uladzislau Rezki (Sony), Marco Elver, Dmitry Vyukov, kasan-dev,
Andrey Ryabinin, Thomas Sailer, linux-hams, Jason A . Donenfeld,
Richard Henderson, linux-alpha, Russell King, linux-arm-kernel,
Catalin Marinas, Huacai Chen, loongarch, Geert Uytterhoeven,
linux-m68k, Dinh Nguyen, Jonas Bonn,
linux-openrisc@vger.kernel.org, Helge Deller, linux-parisc,
Michael Ellerman, linuxppc-dev, Paul Walmsley, linux-riscv,
Heiko Carstens, linux-s390, David S . Miller, sparclinux
In-Reply-To: <20260410120318.727211419@kernel.org>
On Fri, Apr 10, 2026, at 14:19, Thomas Gleixner wrote:
> get_cycles() is not guaranteed to be functional on all systems/platforms
> and the values returned are unitless and not easy to map to something
> useful.
>
> Use ktime_get() instead, which provides nanosecond timestamps and is
> functional everywhere.
>
> This is part of a larger effort to limit get_cycles() usage to low level
> architecture code.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: "Theodore Ts'o" <tytso@mit.edu>
> Cc: linux-ext4@vger.kernel.org
I think this is technically an ABI chance, since the time
difference gets exported through procfs, but the new version
is clearly the right thing to do since it replaces a hardware
specific value with a portable one.
Arnd
^ permalink raw reply
* Re: [patch 10/38] arcnet: Remove function timing code
From: David Woodhouse @ 2026-04-13 15:29 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Michael Grzeschik, netdev, Arnd Bergmann, x86, Lu Baolu, iommu,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, Bernie Thompson, linux-fbdev, Theodore Tso, linux-ext4,
Andrew Morton, Uladzislau Rezki, Marco Elver, Dmitry Vyukov,
kasan-dev, Andrey Ryabinin, Thomas Sailer, linux-hams,
Jason A. Donenfeld, Richard Henderson, linux-alpha, Russell King,
linux-arm-kernel, Catalin Marinas, Huacai Chen, loongarch,
Geert Uytterhoeven, linux-m68k, Dinh Nguyen, Jonas Bonn,
linux-openrisc, Helge Deller, linux-parisc, Michael Ellerman,
linuxppc-dev, Paul Walmsley, linux-riscv, Heiko Carstens,
linux-s390, David S. Miller, sparclinux
In-Reply-To: <20260410120318.253872322@kernel.org>
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On Fri, 2026-04-10 at 14:19 +0200, Thomas Gleixner wrote:
> ARCNET is a museums piece and the function timing can be done with
> ftrace. Remove the cruft.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
> Cc: netdev@vger.kernel.org
> ---
> drivers/net/arcnet/arc-rimi.c | 4 ++--
> drivers/net/arcnet/arcdevice.h | 20 +-------------------
> drivers/net/arcnet/com20020.c | 6 ++----
> drivers/net/arcnet/com90io.c | 6 ++----
> drivers/net/arcnet/com90xx.c | 4 ++--
> 5 files changed, 9 insertions(+), 31 deletions(-)
Acked-by: David Woodhouse <dwmw2@infradead.org>
By coincidence, I took the last of my ARCNET cards to the tip just this
morning...
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^ permalink raw reply
* Re: [patch 15/38] ptp: ptp_vmclock: Replace get_cycles() usage
From: David Woodhouse @ 2026-04-13 15:33 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, Bernie Thompson, linux-fbdev, Theodore Tso, linux-ext4,
Andrew Morton, Uladzislau Rezki, Marco Elver, Dmitry Vyukov,
kasan-dev, Andrey Ryabinin, Thomas Sailer, linux-hams,
Jason A. Donenfeld, Richard Henderson, linux-alpha, Russell King,
linux-arm-kernel, Catalin Marinas, Huacai Chen, loongarch,
Geert Uytterhoeven, linux-m68k, Dinh Nguyen, Jonas Bonn,
linux-openrisc, Helge Deller, linux-parisc, Michael Ellerman,
linuxppc-dev, Paul Walmsley, linux-riscv, Heiko Carstens,
linux-s390, David S. Miller, sparclinux
In-Reply-To: <20260410120318.592237447@kernel.org>
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On Fri, 2026-04-10 at 14:19 +0200, Thomas Gleixner wrote:
> get_cycles() is not really well defined and similar to other usaage of the
> underlying hardware CPU counters the PTP vmclock should use an explicit
> interface as well.
>
> Implement ptp_vmclock_read_cpu_counter() in arm64 and x86 and simplify the
> Kconfig selection while at it.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: David Woodhouse <dwmw2@infradead.org>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Although I might follow up with a change to make this...
> +static inline u64 ptp_vmclock_read_cpu_counter(void)
> +{
> + return cpu_feature_enabled(X86_FEATURE_TSC) ? rdtsc() : 0;
> +}
> +
... depend on TSC_RELIABLE¹, since if the guest doesn't believe that it
is, then the guest shouldn't be trying to use it as the basis for
precise timing.
¹ (Or... one of the other zoo of TSC flags for the gradually reducing
brokenness over the years...)
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^ permalink raw reply
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